Amjadipour, M, Tadich, A, Boeckl, JJ, Lipton-Duffin, J, MacLeod, J, Iacopi, F & Motta, N 2018, 'Quasi free-standing epitaxial graphene fabrication on 3C–SiC/Si(111)', Nanotechnology, vol. 29, no. 14, pp. 145601-145601.
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Growing graphene on SiC thin films on Si is a cheaper alternative to the growth on bulk SiC, and for this reason it has been recently intensively investigated. Here we study the effect of hydrogen intercalation on epitaxial graphene obtained by high temperature annealing on 3C-SiC/Si(111) in ultra-high vacuum. By using a combination of core-level photoelectron spectroscopy, low energy electron diffraction, and near-edge x-ray absorption fine structure (NEXAFS) we find that hydrogen saturates the Si atoms at the topmost layer of the substrate, leading to free-standing graphene on 3C-SiC/Si(111). The intercalated hydrogen fully desorbs after heating the sample at 850 °C and the buffer layer appears again, similar to what has been reported for bulk SiC. However, the NEXAFS analysis sheds new light on the effect of hydrogen intercalation, showing an improvement of graphene's flatness after annealing in atomic H at 600 °C. These results provide new insight into free-standing graphene fabrication on SiC/Si thin films.
Angeloski, A, Gentle, AR, Scott, JA, Cortie, MB, Hook, JM, Westerhausen, MT, Bhadbhade, M, Baker, AT & McDonagh, AM 2018, 'From Lead(II) Dithiocarbamate Precursors to a Fast Response PbS Positive Temperature Coefficient Thermistor', Inorganic Chemistry, vol. 57, no. 4, pp. 2132-2140.
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© 2018 American Chemical Society. PbS submicron crystals were formed by thermolysis of two different lead dithiocarbamate complexes. These precursors were readily synthesized and fully characterized, and in situ synchrotron powder diffraction experiments were performed to characterize their decomposition. The structure and purity of resultant PbS was examined using scanning electron and transmission electron microscopies, powder X-ray diffraction, and infrared spectroscopy. Submicron crystalline PbS was used to create a new PbS thermistor with excellent sensitivity and an ultrarapid thermal response time.
Ba, X, Guo, Y, Zhu, J & Zhang, C 2018, 'An Equivalent Circuit Model for Predicting the Core Loss in a Claw-Pole Permanent Magnet Motor With Soft Magnetic Composite Core', IEEE Transactions on Magnetics, vol. 54, no. 11, pp. 1-6.
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© 1965-2012 IEEE. Soft magnetic composite (SMC) materials and SMC electromagnetic devices have attracted strong research interest in the past decades. However, SMC devices have large core loss that needs to be put into consideration even at the design stage. Effective and accurate prediction of the core loss becomes crucial for the design and optimization of high-performance motors with these materials. Equivalent circuit model is a widely used method for machine analysis, due to the advantages in the fast calculation with a clear physical mechanism. This paper presents an equivalent circuit model to predict the core loss of a claw-pole permanent magnet motor with SMC stator core. All the parameters including the equivalent core-loss resistance in the equivalent circuit model are identified based on the finite-element method to achieve high accuracy, and the effectiveness of the parameters identification methods is experimentally verified. The proposed equivalent circuit model can predict the core loss and motor's performance efficiently both under no-load and loading conditions.
Bao, W, Tang, X, Guo, X, Choi, S, Wang, C, Gogotsi, Y & Wang, G 2018, 'Porous Cryo-Dried MXene for Efficient Capacitive Deionization', Joule, vol. 2, no. 4, pp. 778-787.
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© 2018 Elsevier Inc. Aerogel-like, porous Ti3C2Tx MXene architecture electrode displayed a high electroadsorption capacity for capacitive deionization of saline water. A vacuum freeze-drying process was employed to prevent the restacking of MXene nanosheets due to van der Waals forces, leading to the formation of a porous structure with a large specific surface area. When applied as electrode materials for capacitive deionization, porous MXene demonstrated a high specific capacitance of 156 F/g and a volumetric capacitance of 410 F/cm3 in 1 M sodium chloride (NaCl) electrolyte. The porous Ti3C2Tx MXene electrodes can deliver a high electroadsorption capacity of 118 mg/cm3 (45 mg/g) in 10,000 mg/L NaCl solution (applied voltage: 1.2 V) and excellent cycling stability (up to 60 cycles) in comparison with the restacked MXene and activated carbon electrodes, indicating its promising potential for desalination applications. We report a rationally designed process to produce an aerogel-like porous MXene electrode material for capacitive deionization. The intercalation-delamination of organic compounds and a vacuum freeze-drying technique were employed to prevent the restacking of MXene nanosheets due to van der Waals forces. The porous Ti3C2Tx is hydrophilic and has a well-defined porous structure with a high surface area and high electrical conductivity. When applied as electrodes in a capacitive deionization cell, porous Ti3C2Tx MXene electrodes exhibited an impressively high ion adsorption capacity of 118 mg/cm3 in a salt solution with the concentration of 10,000 mg/L, which is more than 12 times higher than previously reported carbon-based electrode materials. The porous MXene materials may open a new avenue for high-performance capacitive desalination. Porous Ti3C2Tx MXene architectures were prepared and used as electrode materials with a high electrosorption capacity for capacitive deionization of saline or brackish water. The porous Ti3C2Tx MXene elect...
Chen, H 2018, 'Gold nanoparticles improve metabolic profile of mice fed a high-fat diet', J Nanobiotechnology, vol. 16.
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BACKGROUND:Obesity is a high risk for multiple metabolic disorders due to excessive influx of energy, glucose and lipid, often from a western based diet. Low-grade inflammation plays a key role in the progression of such metabolic disorders. The anti-inflammatory property of gold compounds has been used in treating rheumatoid arthritis in the clinic. Previously we found that pure gold nanoparticles (AuNPs, 21 nm) also possess anti-inflammatory effects on the retroperitoneal fat tissue following intraperitoneal injection, by downregulating tumor necrosis factor (TNF) α. However, whether such an effect can change the risk of metabolic disorders in the obese has not been well studied. The study employed C57BL/6 mice fed a pellet high fat diet (HFD, 43% as fat) that were treated daily with AuNPs [low (HFD-LAu) or high (HFD-HAu) dose] via intraperitoneal injection for 9 weeks. In the in vitro study, RAW264.7 macrophages and 3T3-L1 adipocytes were cultured with low and high concentrations of AuNPs alone or together.RESULTS:The HFD-fed mice showed a significant increase in fat mass, glucose intolerance, dyslipidemia, and liver steatosis. The HFD-LAu group showed an 8% reduction in body weight, ameliorated hyperlipidemia, and normal glucose tolerance; while the HFD-HAu group had a 5% reduction in body weight with significant improvement in their glucose intolerance and hyperlipidemia. The underlying mechanism may be attributed to a reduction in adipose and hepatic local proinflammatory cytokine production, e.g. TNFα. In vitro studies of co-cultured murine RAW264.7 macrophage and 3T3-L1 adipocytes supported this proposed mechanism.CONCLUSION:AuNPs demonstrate a promising profile for potential management of obesity related glucose and lipid disorders and are useful as a research tool for the study of biological mechanisms.
Chen, H, Ng, JPM, Tan, Y, McGrath, K, Bishop, DP, Oliver, B, Chan, YL, Cortie, MB, Milthorpe, BK & Valenzuela, SM 2018, 'Gold nanoparticles improve metabolic profile of mice fed a high-fat diet', Journal of Nanobiotechnology, vol. 16, no. 1.
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© 2018 The Author(s). Background: Obesity is a high risk for multiple metabolic disorders due to excessive influx of energy, glucose and lipid, often from a western based diet. Low-grade inflammation plays a key role in the progression of such metabolic disorders. The anti-inflammatory property of gold compounds has been used in treating rheumatoid arthritis in the clinic. Previously we found that pure gold nanoparticles (AuNPs, 21 nm) also possess anti-inflammatory effects on the retroperitoneal fat tissue following intraperitoneal injection, by downregulating tumor necrosis factor (TNF) α. However, whether such an effect can change the risk of metabolic disorders in the obese has not been well studied. The study employed C57BL/6 mice fed a pellet high fat diet (HFD, 43% as fat) that were treated daily with AuNPs [low (HFD-LAu) or high (HFD-HAu) dose] via intraperitoneal injection for 9 weeks. In the in vitro study, RAW264.7 macrophages and 3T3-L1 adipocytes were cultured with low and high concentrations of AuNPs alone or together. Results: The HFD-fed mice showed a significant increase in fat mass, glucose intolerance, dyslipidemia, and liver steatosis. The HFD-LAu group showed an 8% reduction in body weight, ameliorated hyperlipidemia, and normal glucose tolerance; while the HFD-HAu group had a 5% reduction in body weight with significant improvement in their glucose intolerance and hyperlipidemia. The underlying mechanism may be attributed to a reduction in adipose and hepatic local proinflammatory cytokine production, e.g. TNFα. In vitro studies of co-cultured murine RAW264.7 macrophage and 3T3-L1 adipocytes supported this proposed mechanism. Conclusion: AuNPs demonstrate a promising profile for potential management of obesity related glucose and lipid disorders and are useful as a research tool for the study of biological mechanisms.
Chen, Y, Choi, S, Su, D, Gao, X & Wang, G 2018, 'Self-standing sulfur cathodes enabled by 3D hierarchically porous titanium monoxide-graphene composite film for high-performance lithium-sulfur batteries', Nano Energy, vol. 47, pp. 331-339.
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© 2018 Elsevier Ltd Although lithium-sulfur batteries show great promise for next-generation energy storage due to their high energy density, the practical implementation of lithium-sulfur batteries has been largely impeded by the shuttle effect of lithium polysulfides and low areal capacity (< 2 mAh cm−2). Here we rationally design a new self-standing host enabled by a 3D hierarchically-porous titanium monoxide-graphene composite film to overcome the two issues at once. The hierarchically porous graphene scaffold not only can facilitate rapid lithium ion and electron transport, but also provide sufficient spaces to accommodate sulfur and buffer the volume expansion during the lithiation process. In addition, the ultrafine and polar titanium monoxide nanoparticles embedded in the three-dimensional graphene networks show strong chemical anchoring for polysulfides as evidenced by ex-situ X-ray photoelectron spectroscopy analysis, and their inherent metallic conductivity accelerates the redox reaction kinetics. Benefiting from this attractive architecture, the freestanding titanium monoxide-graphene/sulfur cathode delivered a high initial capacity of 1350 mAh g−1 at 0.1 C, a Coulombic efficiency approaching 100%, and a high-rate capacity of 832 mAh g−1 at 2 C. Moreover, when the areal sulfur loading was increased to 5.2 mg cm−2, the titanium monoxide-graphene/sulfur electrode delivered a high areal capacity of 3.2 mAh cm−2 after 300 cycles at 0.2 C, demonstrating excellent cycling performance compared with other recently reported sulfur cathodes with high areal sulfur loadings.
Choi, S, Su, D, Shin, M, Park, S & Wang, G 2018, 'Pomegranate‐Structured Silica/Sulfur Composite Cathodes for High‐Performance Lithium–Sulfur Batteries', Chemistry – An Asian Journal, vol. 13, no. 5, pp. 568-576.
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AbstractPorous materials have many structural advantages for energy storage and conversion devices such as rechargeable batteries, supercapacitors, and fuel cells. When applied as a host material in lithium‐sulfur batteries, porous silica materials with a pomegranate‐like architecture can not only act as a buffer matrix for accommodating a large volume change of sulfur, but also suppress the polysulfide shuttle effect. The porous silica/sulfur composite cathodes exhibit excellent electrochemical performances including a high specific capacity of 1450 mA h g−1, a reversible capacity of 82.9 % after 100 cycles at a rate of C/2 (1 C=1672 mA g−1) and an extended cyclability over 300 cycles at 1 C‐rate. Furthermore, the high polysulfide adsorption property of porous silica has been proven by ex‐situ analyses, showing a relationship between the surface area of silica and polysulfide adsorption ability. In particular, the modified porous silica/sulfur composite cathode, which is treated by a deep‐lithiation process in the first discharge step, exhibits a highly reversible capacity of 94.5 % at 1C‐rate after 300 cycles owing to a formation of lithiated‐silica frames and stable solid‐electrolyte‐interphase layers.
Colusso, AV, McDonagh, A & Cortie, MB 2018, 'X‐ray‐induced reduction of a surfactant/polyoxotungstate hybrid compound', Surface and Interface Analysis, vol. 50, no. 12-13, pp. 1384-1388.
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We investigate the spontaneous reduction of a photochromic surfactant/polyoxotungstate hybrid during repeated X‐ray photoelectron spectroscopy (XPS) scans and show how this effect may confound attempts to use soft X‐rays to characterise materials of this nature. The W4f core‐level spectra revealed a progressive increase of W5+ and W4+ species at the expense of W6+ as irradiation time increased. The samples developed a blue colour attributed to the presence of W4+ and/or W5+. The progressive photoreduction is also associated with a shift of the W6+ peak within the W4f spectrum to lower binding energies. This work highlights the need to consider inadvertent changes in oxidation state during X‐ray photoelectron spectroscopy characterisation of samples containing photoreducible transition metals.
Colusso, AV, McDonagh, AM, Gentle, A & Cortie, MB 2018, 'Photomechanical photochromism in a cetyltrimethylammonium isopolytungstate', RSC Advances, vol. 8, no. 34, pp. 18776-18783.
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The photochromic properties of a hybrid compound comprised of the surfactant cation cetyltrimethylammonium [(C16H33)N(CH3)3]+ and the isopolytungstate anion [H2W12O40]6− is investigated.
Cortie, MB, Cortie, DL & Timchenko, V 2018, 'Heat transfer from nanoparticles for targeted destruction of infectious organisms', International Journal of Hyperthermia, vol. 34, no. 2, pp. 157-167.
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Whereas the application of optically or magnetically heated nanoparticles to destroy tumours is now well established, the extension of this concept to target pathogens has barely begun. Here we examine the challenge of targeting pathogens by this means and, in particular, explore the issues of power density and heat transfer. Depending on the rate of heating, either hyperthermia or thermoablation may occur. This division of the field is fundamental and implies very different sources of excitation and heat transfer for the two modes, and different strategies for their clinical application. Heating by isolated nanoparticles and by agglomerates of nanoparticles is compared: hyperthermia is much more readily achieved with agglomerates and for large target volumes, a factor which favours magnetic excitation and moderate power densities. In contrast, destruction of planktonic pathogens is best achieved by localised thermoablation and very high power density, a scenario that is best delivered by pulsed optical excitation.
Duan, J, Jiang, L, Guo, X, Chen, S, Wang, G & Zhao, C 2018, 'Mxene‐Directed Dual Amphiphilicity at Liquid, Solid, and Gas Interfaces', Chemistry – An Asian Journal, vol. 13, no. 24, pp. 3850-3854.
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AbstractMXenes represent a category of two‐dimensional functional nanomaterials with remarkable structural and chemical properties, which have been manipulated into different architectures for versatile applications. These manipulation processes generally take place at the interfaces between liquid, solid, and gas; and therefore, the investigation of the interfacial property of MXenes is the key. Here we show that MXenes exhibit amphiphilic behaviours at interfaces. Different from common amphiphiles, MXenes have the dual function of both colloidal and molecular activities owing to their two abrupt structural length scales: their large lateral sheet size allows for behaving like colloidal amphiphiles for creating emulsions, while their small sheet thickness allows for serving as molecular amphiphiles for dispersing solid substances. Further, such dual colloidal‐molecular amphiphility has driven MXenes to accumulate at the interfaces of water and nitrogen gas, and the assembly into thin film electrodes for electrochemical energy storage. All these findings open up enormous opportunities for processing various MXenes‐related functional materials and devices.
Duan, N, Xu, W, Feng, H, Wang, S, Guo, Z, Li, Y, Wang, S & Zhu, J 2018, 'A Scalar Hysteresis Model of Ferromagnetic Materials Based on the Elemental Operators', IEEE Transactions on Magnetics, vol. 54, no. 11, pp. 1-4.
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© 1965-2012 IEEE. This paper introduces an elemental operator with biaxial anisotropy to simulate the scalar hysteresis phenomenon of the ferromagnetic materials. The equilibrium position of the magnetization for the elemental operator can be determined by energy minimization. To directly describe the magnetic properties of each operator, an improved analytical expression is deduced by the partial approximate substitutions. Moreover, this approach utilizes the concept of distribution function density in order to consider the interaction field and the coercive force of the elemental operators. To verify the presented model, the magnetic hysteresis of two different magnetic materials under alternating excitations is measured by the magnetic property measurement system and calculated by this elemental operator method, respectively. The comparisons suggest that this elemental operator is effective and can be a useful tool to simulate the scalar magnetic properties of ferromagnetic materials.
Duan, N, Xu, W, Li, Y, Wang, S & Zhu, J 2018, 'Electromagnetic Property Modeling of the Soft Magnetic Composite Material Based on the Limiting Loop Method', Diangong Jishu Xuebao/Transactions of China Electrotechnical Society, vol. 33, no. 20, pp. 4739-4745.
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The soft magnetic composite materials have undergone significant development due to their unique advantages such as low eddy current loss, quasi-isotropy of mechanical and magnetic properties, great design flexibility, low cost and low material consumption during the production process. These materials are suitable for some special electromagnetic devices with 3-D magnetic flux paths, such as transverse flux, claw pole, and axial flux permanent magnet motors. Since the soft magnetic composite materials have been widely used with satisfaction, the magnetic properties, i.e., major hysteresis loops, minor hysteresis loops, and reversal curves, need to be fully understood for developing high performance electromagnetic devices. In this paper, the limiting loop method based on the Preisach model is introduced to simulate the magnetic properties of soft magnetic composite material. A new formulation of the normal Preisach model was derived based on a graphical description of the Preisach theory of magnetic hysteresis. With the help of the Preisach diagrams for the limiting hysteresis loop, the difficulty of identifying the elementary dipole distribution function was circumvented. The new parameter identification method only requires the limiting hysteresis loop as the input data. Besides, to simulate the magnetic properties under different stress, the effect of stress on the magnetization process is taken into account in the improved limiting loop method. Finally, to verify the proposed model, the magnetic properties of SOMALOYTM 500, a classical type of SMC material, are simulated and compared with the experimental results. The accuracy and effectiveness of the model are validated by the actual measurement.
Duan, N, Xu, W, Wang, S & Zhu, J 2018, 'Current Distribution Calculation of Superconducting Layer in HTS Cable Considering Magnetic Hysteresis by Using XFEM', IEEE Transactions on Magnetics, vol. 54, no. 3, pp. 1-4.
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© 2017 IEEE. This paper presents a coupled field-circuit analysis method for the high-temperature superconducting (HTS) cable considering magnetic hysteresis by using the improved extended finite-element method (XFEM). The quasi-3-D cylindrical coordinate HTS cable model is first proposed based on the shell element theory. The quasi-3-D meshing elements are used instead of the traditional 3-D meshing elements to overcome the difficulties in meshing. A new Preisach type hysteresis model of HTS tapes is first combined with the improved XFEM to determine the magnetic hysteresis inductance. A magnetic field-circuit coupled program for current analysis of superconducting layers is coded. The numerical simulation results of this field-circuit coupled method are reported compared with the experimental test results for the case of an HTS cable with two layers.
Farrok, O, Islam, MR, Guo, Y, Zhu, J & Xu, W 2018, 'A Novel Design Procedure for Designing Linear Generators', IEEE Transactions on Industrial Electronics, vol. 65, no. 2, pp. 1846-1854.
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IEEE A number of research works have been carried out based on the optimization of linear generators for harvesting oceanic wave energy, but no significant method of shape optimization for determination of the optimal shape of linear generator has been found. Moreover, inclusion of some parameters, such as shape of linear generator & #x0027;s translator and stator, has been considered out of the scope of the conventional, adaptive or knowledge based genetic algorithm. This paper proposes a novel method through which any type of linear generator & #x0027;s shape can be optimized graphically. A mathematical model of the proposed method including human intervened genetic algorithm is presented. The proposed method has been applied to a direct-drive system based linear generator where the maximization of electrical power output and minimization of steel core volume have been considered as the optimization objectives. The optimization parameters have been further optimized graphically within functional volumetric and electromagnetic constraints to achieve improved design solutions. The proposed method has included comprehensive geometric dimensions, magnetic and electrical parameters. Finally, the shape of steel cores of the translator and special m-shaped stator of the linear generator is determined and simulated using the copper wire. This optimized shape of the linear generator is capable of satisfying the multi-objectives of maximal electrical power generation and reduction of its size. The ANSYS/Ansoft software has been used to create the platform for analyses of the whole system.
Farrok, O, Islam, MR, Islam Sheikh, MR, Guo, Y, Zhu, J & Lei, G 2018, 'Oceanic Wave Energy Conversion by a Novel Permanent Magnet Linear Generator Capable of Preventing Demagnetization', IEEE Transactions on Industry Applications, vol. 54, no. 6, pp. 6005-6014.
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© 1972-2012 IEEE. In the conventional permanent magnet linear generators (PMLGs) used for oceanic wave energy conversion system, demagnetization could cause everlasting degradation in electrical power generation. This paper presents a new design that can be applied to various PMLGs to avoid demagnetization. To check the effectiveness of the proposed technique, a PMLG is considered, which allows both the fixed and variable length of airgaps for analysis. The finite element analysis is used by using the software package ANSYS/Ansoft to simulate the testing PMLG for two conditions: with and without using the proposed technique. Different parameters and characteristics of the PMLG under both conditions are presented in detail. Both the simulation and test results show that the proposed design is able to avoid the demagnetization problem successfully.
Farrok, O, Islam, MR, Sheikh, MRI, Guo, Y & Zhu, JG 2018, 'A Split Translator Secondary Stator Permanent Magnet Linear Generator for Oceanic Wave Energy Conversion', IEEE Transactions on Industrial Electronics, vol. 65, no. 9, pp. 7600-7608.
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IEEE Almost all flux switching permanent magnet linear generators (FSPMLGs) and Vernier hybrid machines contain a heavy solid translator due to their design limitations for electricity generation from the oceanic waves. This paper presents the new design of a FSPMLG in which the translator weight is reduced and an additional static steel core is inserted inside the translator cavity to improve the magnetic flux linkage of the main stator. The generated voltage, current, power, efficiency, core loss, force ripples and cogging force minimization of the proposed FSPMLG are presented. From the dynamic model of the oceanic wave, it is shown that the translator with lower mass could generate electricity more effectively. The special stator and translator sets have been optimized by using the genetic algorithm before they are used in the proposed FSPMLG. To analyze the performance and verify the feasibility of the new design of FSPMLG, the finite element analysis is performed by using the commercial software package ANSYS/Ansoft.
Faunce, TA, Prest, J, Su, D, Hearne, SJ & Iacopi, F 2018, 'On-grid batteries for large-scale energy storage: Challenges and opportunities for policy and technology', MRS Energy & Sustainability, vol. 5, no. 1.
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ABSTRACT
Gao, H, Li, Y, Wang, S, Zhu, J, Yang, Q, Zhang, C & Li, J 2018, 'Losses analysis of soft magnetic ring core under sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) excitations', AIP Advances, vol. 8, no. 5, pp. 056638-056638.
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Practical core losses in electrical machines differ significantly from those experimental results using the standardized measurement method, i.e. Epstein Frame method. In order to obtain a better approximation of the losses in an electrical machine, a simulation method considering sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) waveforms is proposed. The influence of the pulse width modulation (PWM) parameters on the harmonic components in SPWM and SVPWM is discussed by fast Fourier transform (FFT). Three-level SPWM and SVPWM are analyzed and compared both by simulation and experiment. The core losses of several ring samples magnetized by SPWM, SVPWM and sinusoidal alternating current (AC) are obtained. In addition, the temperature rise of the samples under SPWM, sinusoidal excitation are analyzed and compared.
Gao, J, Wu, S, Tan, F, Tian, H, Liu, J & Lu, GQM 2018, 'Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactors', Progress in Natural Science: Materials International, vol. 28, no. 2, pp. 242-245.
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Gao, L, Chen, J, Liu, Y, Yamauchi, Y, Huang, Z & Kong, X 2018, 'Revealing the chemistry of an anode-passivating electrolyte salt for high rate and stable sodium metal batteries', Journal of Materials Chemistry A, vol. 6, no. 25, pp. 12012-12017.
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A compact and conductive solid-electrolyte interphase formed by NaDFOB enables high performance of sodium metal batteries.
Guo, X, Li, K, Bao, W, Zhao, Y, Xu, J, Liu, H & Wang, G 2018, 'Highly Reversible Lithium Polysulfide Semiliquid Battery with Nitrogen‐Rich Carbon Fiber Electrodes', Energy Technology, vol. 6, no. 2, pp. 251-256.
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AbstractFreestanding nitrogen‐doped carbon fiber (NCF) webs saturated with lithium polysulfide solution were prepared as semiliquid cathodes for lithium–sulfur batteries. The NCF webs not only facilitated the transportation of electrons and ions but also immobilized the polysulfide at the cathode side because of strong affinity between the polysulfide and the N‐doped carbon. As a result, these semiliquid cells demonstrated superior electrochemical performance at various current loads. A high reversible capacity of 900 mAh g−1 was achieved after 200 cycles at a current rate of 1 C.
Guo, X, Zhang, J, Song, J, Wu, W, Liu, H & Wang, G 2018, 'MXene encapsulated titanium oxide nanospheres for ultra-stable and fast sodium storage', Energy Storage Materials, vol. 14, pp. 306-313.
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© 2018 Sodium-ion batteries with high power density present tremendous potential for large-scale energy storage applications. However, it remains a big challenge to develop suitable anode materials for ultrafast and highly reversible sodium ion storage. Herein, for the first time, we report a novel strategy to fabricate highly conductive MXene Ti3C2Tx encapsulated titanium oxide spheres (TiO2@Ti3C2Tx) as an excellent anode material for sodium-ion batteries. The MXene layers significantly improve the electronic conductivity of the whole electrode and protect the structural integrity of the TiO2 spheres from electrochemical pulverization, which hence contributes to the formation of a stable solid-electrolyte interface. Meanwhile, the pseudocapacitance of the as-fabricated TiO2@Ti3C2Tx composites enables high-rate capability and long cycle life in sodium-ion batteries. As a result, the hybrid electrode delivers a high reversible capacity of 116 mAh g-1 at 960 mA g-1 up to 5000 cycles. By coupling with a NaCrO2 cathode, a prototype Na-ion full cell achieved a capacity of 103.4 mAh g-1 at 960 mA g-1 and an excellent cycling performance with 73.5% capacity retention after 1000 cycles.
Guo, Y, Seo, DH, Hong, J, Su, D, Wang, H, Zheng, J, Li, X, Murphy, AB & Ostrikov, KK 2018, 'Controlling the adsorption behavior of hydrogen at the interface of polycrystalline CVD graphene', International Journal of Hydrogen Energy, vol. 43, no. 41, pp. 18735-18744.
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© 2018 Hydrogen Energy Publications LLC Polycrystalline graphene films were synthesized from renewable biomaterials in ambient air using a facile and rapid thermal chemical vapour deposition technique. Characterization of the graphene reveals a large surface area, the presence of nanoscale domains and open edges, atomic-level stacking, and high electrical conductivity, which are favorable features for electrochemical hydrogen evolution reactions (HERs). The numerous boundaries and open edges accelerate the gas diffusion process and enlarge the effective reactive surface area for gas evolution, which is responsible for a significant improvement of HER performance and stability compared to a commercial graphene film. The hydrogen adhesion behavior in investigated for both bare Ni foil/foam and graphene grown on Ni foil/foam samples. The hydrogen gas bubbles adhere to the polycrystalline graphene for a long period of time before detaching, in contrast to their behavior on the pristine Ni foil surface. Post treatment of the graphene film using plasma treatment increases the desorption rate of hydrogen bubbles from the surface. The results indicate a wide range of possibilities for use of graphene-based catalysts in electrocatalytic gas evolution reactions.
He, T, Lu, DD-C, Li, L, Zhang, J, Zheng, L & Zhu, J 2018, 'Model-Predictive Sliding-Mode Control for Three-Phase AC/DC Converters', IEEE Transactions on Power Electronics, vol. 33, no. 10, pp. 8982-8993.
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© 1986-2012 IEEE. This paper presents a model-predictive sliding-mode control (MPSMC) scheme for a three-phase ac/dc converter to achieve better stability and dynamic performances. In the conventional model-predictive control method, a proportional-integral (PI) controller is used to generate the active power reference. This traditional model-predictive PI control (MPPIC) scheme, however, produces a large overshoot/undershoot, a long settling time, and a large steady-state error under disturbances. To overcome these deficiencies, a sliding-mode controller is employed to replace the PI controller. Since the control law and the controller are designed based on the system model, the proposed MPSMC scheme can reduce the effects of unexpected disturbances, such as the output voltage demand and the resistance load variations. Both methods have been simulated in MATLAB/Simulink during various disturbances. Compared with the performances of MPPIC, the results obtained from MPSMC show that the settling time of the dc voltage can be minimized by about 91%, and the overshoot can be eliminated from 9.13% during the steady-state progress. The active and reactive power from MPSMC can also be controlled to the desired values, respectively, with a much smaller overshoot/undershoot and a faster response speed. Similar dynamic improvements can be achieved with MPSMC when the dc voltage demand varies. The simulation results are validated by experimental results.
He, T, Zhu, J, Zhang, J & Zheng, L 2018, 'An optimal charging/discharging strategy for smart electrical car parks', Chinese Journal of Electrical Engineering, vol. 4, no. 2, pp. 28-35.
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This paper presents a smart electrical car park model where the power flows among electrical vehicles(EVs) as well as between EVs and the main grid. Based on this model, an optimal charging/discharging scheme is proposed. The fluctuation of hourly electricity rates is considered in this strategy to select a proper charging/discharging rate for each EV with less expenditure during each charging period. The proposed smart electrical car park is able to buy or sell electricity in the form of active and/or reactive power, i.e. kWh and/or kVARh, from or to the main grid to improve the power quality. According to the current state of charge of the EV's battery bank, customers and the grid demands, a control center makes the decisions and sends the instructions of specific charging/discharging mode to each charging station. The performance of the proposed charging/discharging algorithm is simulated in Matlab. A comparison between the proposed and the unregulated charging/discharging strategies has been implemented. The results demonstrate that the proposed scheme can achieve better economic profits for EV customers and increase the commercial benefits for the car park owner.
Huynh, TT, Lem, LLC, Kuramata, A, Phillips, MR & Ton-That, C 2018, 'Kinetics of charge carrier recombination in β−Ga2O3 crystals', Physical Review Materials, vol. 2, no. 10.
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© 2018 American Physical Society. Cathodoluminescence (CL) spectra were measured to determine the characteristics of luminescence bands and carrier dynamics in β-Ga2O3 bulk single crystals. The CL emission was found to be dominated by a broad UV emission peaked at 3.40 eV, which exhibits strong quenching with increasing temperature; however, its spectral shape and energy position remain virtually unchanged. We observed a superlinear increase of CL intensity with excitation density; this kinetics of carrier recombination can be explained in terms of carrier trapping and charge transfer at Fe impurity centers. The temperature-dependent properties of this UV band are consistent with weakly bound electrons in self-trapped excitons with an activation energy of 48±10meV. In addition to the self-trapped exciton emission, a blue luminescence (BL) band is shown to be related to a donor-like defect, which increases significantly in concentration after hydrogen plasma annealing. The point defect responsible for the BL, likely an oxygen vacancy, is strongly coupled to the lattice exhibiting a Huang-Rhys factor of ∼7.3.
Kani, K, Malgras, V, Jiang, B, Hossain, MSA, Alshehri, SM, Ahamad, T, Salunkhe, RR, Huang, Z & Yamauchi, Y 2018, 'Periodically Arranged Arrays of Dendritic Pt Nanospheres Using Cage‐Type Mesoporous Silica as a Hard Template', Chemistry – An Asian Journal, vol. 13, no. 1, pp. 106-110.
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AbstractDendritic Pt nanospheres of 20 nm diameter are synthesized by using a highly concentrated surfactant assembly within the large‐sized cage‐type mesopores of mesoporous silica (LP‐FDU‐12). After diluting the surfactant solution with ethanol, the lower viscosity leads to an improved penetration inside the mesopores. After Pt deposition followed by template removal, the arrangement of the Pt nanospheres is a replication from that of the mesopores in the original LP‐FDU‐12 template. Although it is well known that ordered LLCs can form on flat substrates, the confined space inside the mesopores hinders surfactant self‐organization. Therefore, the Pt nanospheres possess a dendritic porous structure over the entire area. The distortion observed in some nanospheres is attributed to the close proximity existing between neighboring cage‐type mesopores. This new type of nanoporous metal with a hierarchical architecture holds potential to enhance substance diffusivity/accessibility for further improvement of catalytic activity.
King, SR, Gentle, AR, Cortie, MB & McDonagh, AM 2018, 'On the Development of Optical Properties during Thermal Coarsening of Gold Nanoparticle Composites', The Journal of Physical Chemistry C, vol. 122, no. 22, pp. 12098-12105.
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© 2018 American Chemical Society. The changes in optical properties that occur as gold nanoparticles (AuNPs) are thermally converted to a continuous thin film were studied with the purpose of determining the roles of particle coarsening and temperature. In situ reflectance spectroscopy, electron microscopy, and synchrotron X-ray diffraction (XRD) were applied to provide complementary information on the changes in particle size and shape. The AuNPs studied were stabilized with 1-butanethiol, 1-octanethiol, oleylamine (OA), or 4-(pyren-1-yl)butane-1-thiol (PyBuSH). Initially, the films were dark brown or purple because of the plasmon resonance of the AuNPs. As the temperature was increased, the AuNPs started to coalesce and percolate, thereby changing the color of the films to that of bulk gold. Films of AuNPs stabilized with alkanethiols sintered very rapidly, measured as a rapid change in the reflectance spectrum. In contrast, films of AuNPs stabilized with OA or PyBuSH sintered more gradually and at a higher temperature. This permitted the transition to be studied in greater detail than for the alkanethiols. Red-shifted plasmon peaks and increased intensity in the reflectance data and XRD and electron microscopy measurements revealed that a prolonged process of nanoparticle coarsening occurred prior to sintering. The effect of temperature on the optical properties was isolated by monitoring samples as they cooled. The insulator-to-metal transition in these types of composites offers a very flexible platform for controlling spectral properties in the near-infrared region.
Klingberg, J, Shimmon, R, Philp, M, Tahtouh, M, Nic Daeid, N & Fu, S 2018, 'Evaluating the use of Differential Scanning Calorimetry for the analysis of illicit substances and their adulterants', Journal of Forensic Investigation, vol. 6, no. 1, pp. 8-8.
Lei, G, Wang, T, Zhu, J & Guo, Y 2018, 'Robust multiobjective and multidisciplinary design optimization of electrical drive systems', CES Transactions on Electrical Machines and Systems, vol. 2, no. 4, pp. 409-416.
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Li, C, Zang, R, Li, P, Man, Z, Wang, S, Li, X, Wu, Y, Liu, S & Wang, G 2018, 'High Crystalline Prussian White Nanocubes as a Promising Cathode for Sodium‐ion Batteries', Chemistry – An Asian Journal, vol. 13, no. 3, pp. 342-349.
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AbstractPrussian blue and its analogues (PBAs) have been recognized as one of the most promising cathode materials for room‐temperature sodium‐ion batteries (SIBs). Herein, we report high crystalline and Na‐rich Prussian white Na2CoFe(CN)6 nanocubes synthesized by an optimized and facile co‐precipitation method. The influence of crystallinity and sodium content on the electrochemical properties was systematically investigated. The optimized Na2CoFe(CN)6 nanocubes exhibited an initial capacity of 151 mA h g−1, which is close to its theoretical capacity (170 mA h g−1). Meanwhile, the Na2CoFe(CN)6 cathode demonstrated an outstanding long‐term cycle performance, retaining 78 % of its initial capacity after 500 cycles. Furthermore, the Na2CoFe(CN)6 Prussian white nanocubes also achieved a superior rate capability (115 mA h g−1 at 400 mA g−1, 92 mA h g−1 at 800 mA g−1). The enhanced performances could be attributed to the robust crystal structure and rapid transport of Na ions through large channels in the open‐framework. Most noteworthy, the as‐prepared Na2CoFe(CN)6 nanocubes are not only low‐cost in raw materials but also contain a rich sodium content (1.87 Na ions per lattice unit cell), which will be favorable for full cell fabrication and large‐scale electric storage applications.
Li, M, Cortie, DL, Liu, J, Yu, D, Islam, SMKN, Zhao, L, Mitchell, DRG, Mole, RA, Cortie, MB, Dou, S & Wang, X 2018, 'Ultra-high thermoelectric performance in graphene incorporated Cu2Se: Role of mismatching phonon modes', Nano Energy, vol. 53, pp. 993-1002.
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© 2018 Elsevier Ltd A thermoelectric material consisting of Cu2Se incorporated with up to 0.45 wt% of graphene nanoplates is reported. The carbon-reinforced Cu2Se exhibits an ultra-high thermoelectric figure-of-merit of zT = 2.44 ± 0.25 at 870 K. Microstructural characterization reveals dense, nanostructured grains of Cu2Se with multilayer-graphene and graphite agglomerations located at grain boundaries. High temperature X-ray diffraction shows that the graphene incorporated Cu2Se matrix retains a cubic structure and the composite microstructure is chemically stable. Based on the experimental structure, density functional theory was used to calculate the formation energy of carbon point defects and the associated phonon density of states. The isolated carbon inclusion is shown to have a high formation energy in Cu2Se whereas graphene and graphite phases are enthalpically stable relative to the solid solution. Neutron spectroscopy proves that there is a frequency mismatch in the phonon density of states between the carbon honeycomb phases and cubic Cu2Se. This provides a mechanism for the strong scattering of phonons at the composite interfaces, which significantly impedes the conduction of heat and enhances thermoelectric performance.
Li, Y, Zhu, L & Zhu, J 2018, 'Core Loss Calculation Based on Finite-Element Method With Jiles–Atherton Dynamic Hysteresis Model', IEEE Transactions on Magnetics, vol. 54, no. 3, pp. 1-5.
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© 2018 IEEE. For accurate computation of core losses, the Jiles-Atherton ( J - A ) dynamic hysteresis model accounting for hysteresis, eddy current and excess losses is incorporated into the finite-element method (FEM). The J - A dynamic hysteresis model is constructed by combining the traditional J - A hysteresis model with the models of instantaneous eddy current and excess losses. The J - A model parameters and dynamic loss coefficients are determined by fitting the models to the measurement data of a single sheet tester (SST 500) and Epstein frame tester. To find the robust best fit, the particle swarm optimization algorithm is employed. By using the proposed J - A dynamic hysteresis model and FEM, the magnetic characteristics of a magnetic core is simulated and the core loss distribution within the core obtained. The calculated and measured results are compared to show the accuracy and effectiveness of the proposed model.
Lin, M, Shan, S, Liu, P, Ma, L, Huang, L, Yang, M, Lawson, T, Wang, Z, Huang, Z, Shi, B, Yan, L & Liu, Y 2018, 'Hydroxyl-Functional Groups on Graphene Trigger the Targeted Delivery of Antitumor Drugs', Journal of Biomedical Nanotechnology, vol. 14, no. 8, pp. 1420-1429.
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© 2018 American Scientific Publishers. An efficient and targeted treatment for tumor cells is demonstrated. This targeting is based upon the strong affinity between hydroxyl-functional groups on graphene and acidic tumors. The hydroxylated graphene (GOH) with a unique 2D architecture further improve the targeting capacity of the system via an enhanced permeability and retention (EPR) process. Polyethylene glycol (PEG) was employed for better biocompatibility and the antitumor drug doxorubicin (DOX) was then incorporated. These additions created a biocompatible system with a superior pH-dependent drug release property. Its proficiency was due to its ability to pass through cell membranes via a process of endocytosis and exocytosis. The results from a Transwell co-culture system discovered that the PEG-GOH-DOX system had a large impact on tumor cell viability (less than 10% survived after treatment) and little influence on normal cells (more than 80% survived). An in vitro 3D tumor model study demonstrated that the size of the PEG-GOH-DOX treated tumor was 50% less than that of the pristine DOX treated tumor. In vivo data indicated that the PEG-GOH-DOX system was able to inhibit the size of tumors by a factor of 6.5 when compared to the untreated tumors.
Liu, C, Lei, G, Ma, B, Guo, Y & Zhu, J 2018, 'Robust Design of a Low-Cost Permanent Magnet Motor with Soft Magnetic Composite Cores Considering the Manufacturing Process and Tolerances', Energies, vol. 11, no. 8, pp. 2025-2025.
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This paper uses the Taguchi method to optimize the manufacturing process and robust design of a low-cost permanent magnet motor with soft magnetic composite (SMC) cores. For the manufacturing process, SMC cores are produced by using the molding technology without any wire cutting costs. To maximize the relative permeability and minimize the core loss, the Taguchi method is employed to identify the best control factor values for the heat treatment of SMC cores based on a series of experimental results. Due to the manufacturing tolerances, there are significant uncertainties in the core densities and motor dimensions, which will result in big performance variations for the SMC motors in the batch production. To obtain a robust design less sensitive to these tolerances, the conventional Taguchi parameter design method and a sequential Taguchi optimization method are presented to maximize the average torque and minimize the core loss of a low-cost PM motor. Through comparison, it is found that the proposed optimization method is efficient. It can provide an optimal design with better motor performance and manufacturing quality. The proposed method will benefit the industrial production of cost-effective PM-SMC motors with robust and compact designs.
Liu, C, Lu, J, Wang, Y, Lei, G, Zhu, J & Guo, Y 2018, 'Design Issues for Claw Pole Machines with Soft Magnetic Composite Cores', Energies, vol. 11, no. 8, pp. 1998-1998.
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By using global ring winding, the torque coefficient of the transverse flux machine (TFM) is proportional to its number of pole pairs, and thus the TFM possesses high torque density ability when compared with other electrical machines. As a special kind of TFM, the claw pole machine (CPM) can have more torque due to its special claw pole teeth. The manufacturing of CPM or TFM with silicon steels was very difficult in the past, and is a handicap for the progress of this kind of machine. Thanks to the advent of soft magnetic composite (SMC) materials, the manufacturing process of CPM has become more and more simple. More attention has been paid to this kind of technology, and some mass production CPMs with SMC cores have appeared. However, there are few works that discuss the key design issues for this kind of machine. In this paper, a small CPM with SMC is used as as a research benchmark. Various design methods that can be adopted to improve its performance have been studied, including unequal stator claw pole teeth, a skewing magnet design, consequent pole design, and etc. The 3D finite element method (FEM) is used for the machine analysis, and it is verified by the experimental results of a CPM with SMC cores.
Liu, Z, Zhu, J & Zhu, L 2018, 'Accurate Calculation of Eddy Current Loss in Litz-Wired High-Frequency Transformer Windings', IEEE Transactions on Magnetics, vol. 54, no. 11, pp. 1-5.
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© 1965-2012 IEEE. As the power capacity of high-frequency transformer increases, the requirement on transformer efficiency gets higher and higher. Due to the rapid increase of switching frequency, the eddy current loss of high-frequency transformer windings becomes more and more significant. The use of litz-wire can reduce the high-frequency loss to some extent. The two most well-known methods for calculating the high-frequency power loss in round wire windings are the Dowell and Ferreira methods. These two models, however, are inaccurate under some conditions, because of the assumptions made in the establishment of the models. This paper presents an accurate model to calculate the power loss in litz-wired windings, through analysis of the skin and proximity effects from a single conductor to the whole twisted litz-wire. To extend the model into a 3-D calculation model, the twist effect is considered. The new model has a good accuracy within a wide bandwidth of frequency, and can be used for the electromagnetic design of high-frequency devices.
Ma, B, Lei, G, Liu, C, Zhu, J & Guo, Y 2018, 'Robust Tolerance Design Optimization of a PM Claw Pole Motor With Soft Magnetic Composite Cores', IEEE Transactions on Magnetics, vol. 54, no. 3, pp. 1-4.
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© 1965-2012 IEEE. In the past decades, various methods have been investigated for assessing performance variation and robust optimization for electromagnetic device design under uncertainties and/or tolerances. However, in actual production, the manufacturing tolerances are variable to a certain extent, which can be optimized for integrating the performance, manufacturing cost, and production quality. This paper proposes a tolerance design optimization approach by optimizing the design parameters and tolerances simultaneously based on design for six sigma technique. A permanent magnet claw pole motor with soft magnetic composite cores is optimized by using the proposed approach. For this high-dimensional optimization problem involving electromagnetic and thermal performance, Kriging model and 3-D thermal network model are employed under the multilevel framework for increasing the optimization efficiency. Finally, through the analysis, the proposed robust tolerance optimization method shows good performance with improved motor performance as well as the diversity controlling without cost increasing.
Ma, B, Lei, G, Zhu, J & Guo, Y 2018, 'Design Optimization of a Permanent Magnet Claw Pole Motor With Soft Magnetic Composite Cores', IEEE Transactions on Magnetics, vol. 54, no. 3, pp. 1-4.
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© 2017 IEEE. In our previous study, the claw pole motor (CPM) shows promising magnetic concentrating performance for permanent magnet motors with soft magnetic composite cores. Meanwhile, its relatively complex structure also increases the core loss and cogging torque. To conduct the high dimensional optimization of the CPM with comprehensive analysis models, this paper presents an improved multilevel strategy of high efficiency. Since the holistic performances, including output torque, efficiency, cogging torque, and back electromotive force, are considered, an orthogonal design is utilized for the surrogate model building for increasing the optimization efficiency. A full factor sample method for the surrogate model is also conducted for comparison. The similar optimization results with the two kinds of models prove the effectiveness of the proposed method and optimal design.
Ma, B, Lei, G, Zhu, J, Guo, Y & Liu, C 2018, 'Application-Oriented Robust Design Optimization Method for Batch Production of Permanent-Magnet Motors', IEEE Transactions on Industrial Electronics, vol. 65, no. 2, pp. 1728-1739.
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© 2017 IEEE. From the perspective of industrial production, the design and optimization of electrical machines are application oriented, including maximizing production quality and minimizing production cost in terms of different manufacturing conditions. To achieve these goals, this study presents an efficient application-oriented robust design optimization method for permanent-magnet (PM) motors. The method consists of two main contributions. The first one is the development of an overall optimization strategy, including qualitative and quantitative analyses to provide possible options for an application. Multiphysics analysis, uncertainty analysis, production cost, and optimization models need to be investigated. The second one proposes a multilevel optimization method for the high-dimensional robust design problem of each option. To illustrate the advantages of the proposed method, PM motorswith soft magnetic composite cores are investigated for domestic applications. The design optimization is conducted in terms of three motor options and three batch production volumes for both conventional deterministic and robust approaches, and it consists of 18 high-dimensional multiphysics optimization problems in total. Main optimization results are presented and discussed. Experimental and simulation results are presented to validate the effectiveness of the proposed models and methods.
Ma, B, Zheng, J, Lei, G, Zhu, J, Guo, Y & Wu, J 2018, 'A Robust Design Optimization Method for Electromagnetic Devices With Interval Uncertainties', IEEE Transactions on Magnetics, vol. 54, no. 11, pp. 1-4.
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© 1965-2012 IEEE. High reliability is usually demanded for the design of electromagnetic devices. Interval uncertainties widely exist in the robust optimization problems, and the bounds of the design parameters can be only obtained instead of their specific distributions. To solve this kind of problem efficiently, this paper presents a robust optimization approach based on the Chebyshev interval method to estimate the extreme values of the constraints and objectives. To demonstrate the effectiveness of the method, the Testing Electromagnetic Analysis Methods workshop problem 22 and a brushless dc wheel motor optimization benchmark problem are investigated with interval uncertainties of the relevant parameters. Deterministic and robust optimizations considering the worst case with uniform sampling are also conducted for comparison. The optimization results illustrate the effectiveness of the proposed method.
Mahmood, A, Tabassum, H, Zhao, R, Guo, W, Aftab, W, Liang, Z, Sun, Z & Zou, R 2018, 'Fe2N/S/N Codecorated Hierarchical Porous Carbon Nanosheets for Trifunctional Electrocatalysis', Small, vol. 14, no. 49, pp. 1803500-1803500.
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AbstractConstruction of multifunctional highly active earth‐abundant electrocatalysts on a large scale is a great challenge due to poor control over nanostructural features and limited active sites. Here, a simple methodology to tailor metal–organic frameworks (MOFs) to extract highly active multifunctional electrocatalysts on a large scale for oxygen reduction (ORR), oxygen evolution (OER), and hydrogen evolution reaction (HER) is presented. The N, S codoped Fe2N decorated highly porous and defect‐rich carbon nanosheets are grown using MOF xerogels, melamine, and polyvinylpyrollidone. The resulting catalyst exhibits excellent activity for ORR with an onset (0.92 V) and half‐wave (0.81 V) potential similar to state‐of‐the‐art Pt/C catalysts. The catalyst also shows outstanding OER and HER activities with a small overpotential of 360 mV in 1 m KOH and −123 mV in 0.5 m H2SO4 at a current density of 10 mA cm−2, respectively. Excellent catalytic properties are further supported by theoretical calculations where relevant models are built and various possible activation sites are identified by first‐principles calculations. The results suggest that the carbon atoms adjacent to heteroatoms as well as Fe2–N sites present the active sites for improved catalytic response, which is in agreement with the experimental results.
Philp, M & Fu, S 2018, 'A review of chemical ‘spot’ tests: A presumptive illicit drug identification technique', Drug Testing and Analysis, vol. 10, no. 1, pp. 95-108.
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AbstractChemical ‘spot’ tests are a presumptive illicit drug identification technique commonly used by law enforcement, border security personnel, and forensic laboratories. The simplicity, low cost, and rapid results afforded by these tests make them particularly attractive for presumptive identification globally. In this paper, we review the development of these long‐established methods and discuss color test recommendations and guidelines. A search of the scientific literature revealed the chemical reactions occurring in many color tests are either not actively investigated or reported as unknown. Today, color tests face many challenges, from the appearance of new psychoactive substances to concerns regarding selectivity, sensitivity, and safety. Advances in technology have seen color test reagents used in digital image color analysis, solid sensors, and microfluidic devices for illicit drug detection. This summarizes current research and suggests the future of presumptive color testing.
Philp, M, Shimmon, R, Tahtouh, M & Fu, S 2018, 'Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones', Journal of Visualized Experiments, vol. 2018, no. 132.
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© 2018 Journal of Visualized Experiments. Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.
Pradeepkumar, A, Zielinski, M, Bosi, M, Verzellesi, G, Gaskill, DK & Iacopi, F 2018, 'Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon', Journal of Applied Physics, vol. 123, no. 21, pp. 215103-215103.
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Heteroepitaxial 3C-SiC films on silicon substrates are of technological interest as enablers to integrate the excellent electrical, electronic, mechanical, thermal, and epitaxial properties of bulk silicon carbide into well-established silicon technologies. One critical bottleneck of this integration is the establishment of a stable and reliable electronic junction at the heteroepitaxial interface of the n-type SiC with the silicon substrate. We have thus investigated in detail the electrical and transport properties of heteroepitaxial cubic silicon carbide films grown via different methods on low-doped and high-resistivity silicon substrates by using van der Pauw Hall and transfer length measurements as test vehicles. We have found that Si and C intermixing upon or after growth, particularly by the diffusion of carbon into the silicon matrix, creates extensive interstitial carbon traps and hampers the formation of a stable rectifying or insulating junction at the SiC/Si interface. Although a reliable p-n junction may not be realistic in the SiC/Si system, we can achieve, from a point of view of the electrical isolation of in-plane SiC structures, leakage suppression through the substrate by using a high-resistivity silicon substrate coupled with deep recess etching in between the SiC structures.
Prasansuklab, A, Theerasri, A, Payne, M, Ung, AT & Tencomnao, T 2018, 'Acid-base fractions separated from Streblus asper leaf ethanolic extract exhibited antibacterial, antioxidant, anti-acetylcholinesterase, and neuroprotective activities', BMC Complementary and Alternative Medicine, vol. 18, no. 1, pp. 223-223.
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Streblus asper is a well-known plant native to Southeast Asia. Different parts of the plant have been traditionally used for various medicinal purposes. However, there is very little scientific evidence reporting its therapeutic benefits for potential treatment of Alzheimer's disease (AD). The study aimed to evaluate antibacterial, antioxidant, acetylcholinesterase (AChE) inhibition, and neuroprotective properties of S. asper leaf extracts with the primary objective of enhancing therapeutic applications and facilitating activity-guided isolation of the active chemical constituents.The leaves of S. asper were extracted in ethanol and subsequently fractionated into neutral, acid and base fractions. The phytochemical constituents of each fraction were analyzed using GC-MS. The antibacterial activity was evaluated using a broth microdilution method. The antioxidant activity was determined using DPPH and ABTS radical scavenging assays. The neuroprotective activity against glutamate-induced toxicity was tested on hippocampal neuronal HT22 cell line by evaluating the cell viability using MTT assay. The AChE inhibitory activity was screened by thin-layer chromatography (TLC) bioautographic method.The partition of the S. asper ethanolic leaf extract yielded the highest mass of phytochemical constitutions in the neutral fraction and the lowest in the basic fraction. Amongst the three fractions, the acidic fraction showed the strongest antibacterial activity against gram-positive bacteria. The antioxidant activities of three fractions were found in the order of acidic > basic > neutral, whereas the decreasing order of neuroprotective activity was neutral > basic > acidic. TLC bioautography revealed one component in the neutral fraction exhibited anti-AChE activity. While in the acid fraction, two components showed inhibitory activity against AChE. GC-MS analysis of three fractions showed the presence of major phytochemical constituents including terpenoids, steroids, phenol...
Pushpamalar, J, Langford, SJ, Ahmad, MB, Lim, YY & Hashim, K 2018, 'Eco-friendly smart hydrogels for soil conditioning and sustain release fertilizer', International Journal of Environmental Science and Technology, vol. 15, no. 10, pp. 2059-2074.
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Rahman, MA, Scott, JA, Gentle, A, Phillips, MR & Ton-That, C 2018, 'A facile method for bright, colour-tunable light-emitting diodes based on Ga-doped ZnO nanorods', Nanotechnology, vol. 29, no. 42, pp. 425707-425707.
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© 2018 IOP Publishing Ltd. Bottom-up fabrication of nanowire-based devices is highly attractive for oxide photonic devices because of high light extraction efficiency; however, unsatisfactory electrical injection into ZnO and poor carrier transport properties of nanowires severely limit their practical applications. Here, we demonstrate that ZnO nanorods doped with Ga donors by in situ dopant incorporation during vapour-solid growth exhibit superior optoelectronic properties that exceed those currently synthesised by chemical vapour deposition, and accordingly can be electrically integrated into Si-based photonic devices. Significantly, the doping method was found to improve the nanorod quality by decreasing the concentration of point defects. Light-emitting diodes (LEDs) fabricated from the Ga-doped ZnO nanorod/p-Si heterojunction display bright and colour-tunable electroluminescence (EL). These nanorod LEDs possess a dramatically enhanced performance and an order of magnitude higher EL compared with equivalent devices fabricated with undoped nanorods. These results point to an effective route for large-scale fabrication of conductive, single-crystalline ZnO nanorods for photonic and optoelectronic applications.
Rohanim Asari, A, Guo, Y & Zhu, J 2018, 'Core Loss Measurement of Somaloy 700 Material Under Round Loci of Magnetic Flux Density', International Journal of Engineering & Technology, vol. 7, no. 3.25, pp. 109-109.
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The magnetic properties of SOMALOY 700 material are aggressively studied by some researchers in predicting the production of total core loss during the magnetization process of that particular material. Core loss is resulted due to the alternating and rotating magnetic fields in a core material. The magnetic properties of SOMALOY 700 material is studied in this paper since it offers the low core loss during the operation. 2-D measurement were conducted by controlling the fluxes to be circular with the help of LabVIEW while the core loss calculations were calculated by MathCAD. The performance of SOMALOY 700 material at different frequencies were compared. The finding indicates that the magnetization at 1000 Hz contributes higher core loss compared to the magnetization at 500 Hz and 50 Hz. The details of SOMALOY 700 material provide good information to practitioners in designing electrical machine at different variation of frequencies.
Scott, JA, Angeloski, A, Aharonovich, I, Lobo, CJ, McDonagh, A & Toth, M 2018, 'In situstudy of the precursor conversion reactions during solventless synthesis of Co9S8, Ni3S2, Co and Ni nanowires', Nanoscale, vol. 10, no. 33, pp. 15669-15676.
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Synthesis of Co9S8, Ni3S2, Co and Ni nanowires by solventless thermolysis of a mixture of metal(ii) acetate and cysteine in vacuum is reported.
Solowij, N, Broyd, SJ, Beale, C, Prick, J-A, Greenwood, L-M, van Hell, H, Suo, C, Galettis, P, Pai, N, Fu, S, Croft, RJ, Martin, JH & Yücel, M 2018, 'Therapeutic Effects of Prolonged Cannabidiol Treatment on Psychological Symptoms and Cognitive Function in Regular Cannabis Users: A Pragmatic Open-Label Clinical Trial', Cannabis and Cannabinoid Research, vol. 3, no. 1, pp. 21-34.
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Introduction: Chronic cannabis use has been associated with impaired cognition and elevated psychological symptoms, particularly psychotic-like experiences. While Δ9-tetrahydrocannabinol (THC) is thought to be primarily responsible for these deleterious effects, cannabidiol (CBD) is purported to have antipsychotic properties and to ameliorate cognitive, symptomatic, and brain harms in cannabis users. However, this has never been tested in a prolonged administration trial in otherwise healthy cannabis users. Here, we report the first study of prolonged CBD administration to a community sample of regular cannabis users in a pragmatic trial investigating potential restorative effects of CBD on psychological symptoms and cognition. Materials and Methods: Twenty frequent cannabis users (16 male, median age 25 years) underwent a 10-week open-label trial of 200 mg of daily oral CBD treatment, while continuing to use cannabis as usual. The majority of participants were daily cannabis users who had used cannabis for several years (median 5.5 years of regular use). Participants underwent psychological and cognitive assessments at baseline (BL) and post-treatment (PT) and were monitored weekly throughout the trial. Results: CBD was well tolerated with no reported side effects; however, participants retrospectively reported reduced euphoria when smoking cannabis. No impairments to cognition were found, nor were there deleterious effects on psychological function. Importantly, participants reported significantly fewer depressive and psychotic-like symptoms at PT relative to BL, and exhibited improvements in attentional switching, verbal learning, and memory. Increased plasma CBD concentrations were associated with improvements in attentional control and beneficial changes in psychological symptoms. Greater benefits were observed in dependent than in nondependent cannabis users. Conclusions: Prolonged CBD treatment appears to have promising therapeutic effects for im...
Song, J, Zhang, C, Guo, X, Zhang, J, Luo, L, Liu, H, Wang, F & Wang, G 2018, 'Entrapping polysulfides by using ultrathin hollow carbon sphere-functionalized separators in high-rate lithium-sulfur batteries', Journal of Materials Chemistry A, vol. 6, no. 34, pp. 16610-16616.
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Novel ultrathin hollow carbon spheres with a nonporous shell are employed as polysulfide reservoirs to improve the overall performance of Li-S batteries.
Sornalingam, K, McDonagh, A, Zhou, JL, Johir, MAH & Ahmed, MB 2018, 'Photocatalysis of estrone in water and wastewater: Comparison between Au-TiO2 nanocomposite and TiO2, and degradation by-products', Science of The Total Environment, vol. 610-611, pp. 521-530.
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© 2017 Elsevier B.V. Gold-modified TiO2 (Au-TiO2) photocatalysts were utilised for the degradation of estrone (E1), a major endocrine disrupting chemical in water and wastewater. Au-TiO2 catalysts were synthesised by a deposition-precipitation method with gold loadings of 0–8% (wt%). The Au-TiO2 nanocomposite exhibited superior activity compared to P25 TiO2 under UVA (λ = 365 nm), cool white (λ > 420 nm) and green (λ = 523 nm) light emitting diodes (LEDs), for treating 1 mg l− 1 of E1. The 4 wt% Au loading was found to produce the best photocatalytic activity with a rate constant of 2.44 ± 0.36 h− 1, compared to 0.06 ± 0.01 h− 1 for P25 TiO2, under visible light. In total 4 by-products were identified, one from negative ionization mode (m/z = 269) and three from positive ionization mode (m/z = 287) during photocatalysis, which were also degraded with time by Au-TiO2. For different water matrices, the photodegradation rate of E1 decreased in the order: ultrapure water > synthetic wastewater ≈ wastewater effluent from membrane bio-reactor. Overall, 4 wt% Au-TiO2 demonstrated superior performance compared to P25 TiO2 in water and wastewater.
Su, D, Zhou, D, Wang, C & Wang, G 2018, 'Lithium‐Sulfur Batteries: Toward High Performance Lithium–Sulfur Batteries Based on Li2S Cathodes and Beyond: Status, Challenges, and Perspectives (Adv. Funct. Mater. 38/2018)', Advanced Functional Materials, vol. 28, no. 38, pp. 1870273-1870273.
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Su, D, Zhou, D, Wang, C & Wang, G 2018, 'Toward High Performance Lithium–Sulfur Batteries Based on Li2S Cathodes and Beyond: Status, Challenges, and Perspectives', Advanced Functional Materials, vol. 28, no. 38, pp. 1800154-1800154.
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AbstractLithium sulfur (Li–S) batteries are attracting ever‐increasing interests as a new generation rechargeable battery system with high energy density and low cost. Li–S batteries will fulfill their theoretical potential if the problem of polysulfides shuttle effect can be solved. Therefore, tremendous efforts have been devoted to overcoming this problem from the aspects of physical confinement and chemisorption of polysulfides. Recently, it is discovered that replacing sulfur cathodes with lithium sulfide (Li2S) can not only largely avoid the volume expansion issue during cycling, but it can also work with anode materials other than lithium metal to eliminate serious safety concerns for traditional Li–S batteries. However, there are many challenges for developing practical Li metal‐free Li–S battery systems, because Li2S‐based cathode materials are moisture‐sensitive and prelithiation of the non‐Li metal anode materials is usually required for practical applications. This study reviews the recent advances of Li‐S batteries based on Li2S cathode with features of improved safety, high Coulombic efficiency, and high energy density. The electrode activation processes are also discussed, which is critical for achieving high performances. It is anticipated that the extensive efforts will lead to breakthroughs for the development of Li2S cathode ‐based Li‐S batteries.
Sun, B, Li, P, Zhang, J, Wang, D, Munroe, P, Wang, C, Notten, PHL & Wang, G 2018, 'Dendrite‐Free Sodium‐Metal Anodes for High‐Energy Sodium‐Metal Batteries', Advanced Materials, vol. 30, no. 29, pp. 1801334-1801334.
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AbstractSodium (Na) metal is one of the most promising electrode materials for next‐generation low‐cost rechargeable batteries. However, the challenges caused by dendrite growth on Na metal anodes restrict practical applications of rechargeable Na metal batteries. Herein, a nitrogen and sulfur co‐doped carbon nanotube (NSCNT) paper is used as the interlayer to control Na nucleation behavior and suppress the Na dendrite growth. The N‐ and S‐containing functional groups on the carbon nanotubes induce the NSCNTs to be highly “sodiophilic,” which can guide the initial Na nucleation and direct Na to distribute uniformly on the NSCNT paper. As a result, the Na‐metal‐based anode (Na/NSCNT anode) exhibits a dendrite‐free morphology during repeated Na plating and striping and excellent cycling stability. As a proof of concept, it is also demonstrated that the electrochemical performance of sodium–oxygen (Na–O2) batteries using the Na/NSCNT anodes show significantly improved cycling performances compared with Na–O2 batteries with bare Na metal anodes. This work opens a new avenue for the development of next‐generation high‐energy‐density sodium‐metal batteries.
Sun, B, Pompe, C, Dongmo, S, Zhang, J, Kretschmer, K, Schröder, D, Janek, J & Wang, G 2018, 'Challenges for Developing Rechargeable Room‐Temperature Sodium Oxygen Batteries', Advanced Materials Technologies, vol. 3, no. 9, pp. 1800110-1800110.
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AbstractThe development of high energy‐density and low‐cost energy storage devices requires new chemistry beyond the horizon of current state‐of‐the‐art lithium‐ion batteries. Recently, sodium/oxygen (Na/O2) batteries have attracted great attention as one possible battery type among the new generation of rechargeable batteries. They convince with superior energy density, a relatively simple cell reaction, and abundance of sodium. Research on Na/O2 batteries has progressed quickly in recent years. However, a fundamental understanding underpinning the complex chemical/electrochemical side reactions is still insufficient, and many challenges remain unsolved for real practical applications. Herein, recent achievements and remaining issues for the development of rechargeable Na/O2 batteries are summarized. The discussion focuses on cell reaction mechanisms as well as cathode materials, sodium anodes, and electrolytes as key components of this type of battery. Furthermore, perspectives for future research and technological advances of Na/O2 batteries are outlined.
Sun, B, Pompe, C, Dongmo, S, Zhang, J, Kretschmer, K, Schröder, D, Janek, J & Wang, G 2018, 'Next‐Generation Rechargeable Batteries: Challenges for Developing Rechargeable Room‐Temperature Sodium Oxygen Batteries (Adv. Mater. Technol. 9/2018)', Advanced Materials Technologies, vol. 3, no. 9, pp. 1870035-1870035.
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Sun, X, Su, B, Wang, S, Yang, Z, Lei, G, Zhu, J & Guo, Y 2018, 'Performance Analysis of Suspension Force and Torque in an IBPMSM With V-Shaped PMs for Flywheel Batteries', IEEE Transactions on Magnetics, vol. 54, no. 11, pp. 1-4.
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© 1965-2012 IEEE. Due to the advantages such as high energy density, high power density, high cyclic life, and environmentally friendly, the flywheel battery has the potential to solve the problem of energy storage. In order to improve the torque density and suspension performance of bearingless synchronous permanent magnet (PM) synchronous motors (BPMSMs), a novel rotor structure with V-shaped PMs is designed in this paper. Furthermore, the interior BPMSM (IBPMSM) with V-shaped PM which used for flywheel batteries of electric vehicles is researched in detail. Especially, the influence of geometrical parameters of V-shaped PM on suspension force and electromagnetic torque is investigated. Moreover, the corresponding static electrical magnetic characteristics including inductances and electromagnetic torque are also studied. The finite-element method is employed to evaluate the theoretical analysis of the proposed IBPMSM. In addition, the optimized motor is validated to have good suspension performance by some experiments.
Sun, Y, Zhang, W, Wang, B, Xu, X, Chou, J, Shimoni, O, Ung, AT & Jin, D 2018, 'A supramolecular self-assembly strategy for upconversion nanoparticle bioconjugation', Chemical Communications, vol. 54, no. 31, pp. 3851-3854.
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An efficient surface modification and bioconjugation strategy for upconversion nanoparticles is reported via supramolecular host–guest self-assembly.
Tabassum, H, Zou, R, Mahmood, A, Liang, Z, Wang, Q, Zhang, H, Gao, S, Qu, C, Guo, W & Guo, S 2018, 'A Universal Strategy for Hollow Metal Oxide Nanoparticles Encapsulated into B/N Co‐Doped Graphitic Nanotubes as High‐Performance Lithium‐Ion Battery Anodes', Advanced Materials, vol. 30, no. 8, pp. 1705441-1705441.
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AbstractYolk–shell nanostructures have received great attention for boosting the performance of lithium‐ion batteries because of their obvious advantages in solving the problems associated with large volume change, low conductivity, and short diffusion path for Li+ ion transport. A universal strategy for making hollow transition metal oxide (TMO) nanoparticles (NPs) encapsulated into B, N co‐doped graphitic nanotubes (TMO@BNG (TMO = CoO, Ni2O3, Mn3O4) through combining pyrolysis with an oxidation method is reported herein. The as‐made TMO@BNG exhibits the TMO‐dependent lithium‐ion storage ability, in which CoO@BNG nanotubes exhibit highest lithium‐ion storage capacity of 1554 mA h g−1 at the current density of 96 mA g−1, good rate ability (410 mA h g−1 at 1.75 A g−1), and high stability (almost 96% storage capacity retention after 480 cycles). The present work highlights the importance of introducing hollow TMO NPs with thin wall into BNG with large surface area for boosting LIBs in the terms of storage capacity, rate capability, and cycling stability.
Tai, MC, Gentle, AR, Arnold, MD & Cortie, MB 2018, 'Spontaneous growth of polarizing refractory metal ‘nano-fins’', Nanotechnology, vol. 29, no. 10, pp. 105702-105702.
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© 2018 IOP Publishing Ltd. Traditional polymer polarizers degrade in harsh environments and at high temperatures, reducing the polarization effect. In contrast, polarizers produced with refractory metals have vastly improved thermal stability and resistance to harsh environments but are expensive to fabricate. Here we demonstrate prototype refractory metal wire grid polarizers produced by co-sputtering molybdenum and aluminum under specific conditions. Removal of the aluminum through selective dissolution enables the nanostructure array to transmit light. The polarization spans 500-1100 nm and the extinction ratio significantly increases to >100. Possessing broadband polarization and sufficient extinction ratios, the new polarizing film has potential applications in coatings for sunglasses, windows, pyrometers, scientific instruments, and LCD panels.
Tang, X, Guo, X, Wu, W & Wang, G 2018, '2D Metal Carbides and Nitrides (MXenes) as High‐Performance Electrode Materials for Lithium‐Based Batteries', Advanced Energy Materials, vol. 8, no. 33, pp. 1801897-1801897.
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AbstractTremendous efforts are devoted to developing advanced electrode materials with superior electrochemical performance, high energy density, and high power density for energy storage and conversion. Two‐dimensional (2D) materials, owing to their unique properties, have shown great potential for energy storage. Following the discovery of graphene, a new family of 2D transition metal carbides/nitrides, MXenes, derived from MAX phase precursors, have attracted extensive attention in recent years. The superior physical and chemical properties of MXenes include high mechanical strength, excellent electrical conductivity, multiple possible surface terminations, hydrophilic features, superior specific surface area, and the ability to accommodate intercalants. When applied as electrodes in lithium‐based batteries, MXenes have demonstrated excellent performance. In this progress report, the authors summarize the recent advances of MXenes and MXene‐based composites in terms of synthesis strategies, morphology engineering, physical/chemical properties, and their applications in lithium‐ion batteries and lithium–sulfur batteries. Furthermore, challenges and perspectives for MXenes and MXene‐based composites for lithium‐based energy storage devices are also outlined.
Tang, X, Liu, H, Guo, X, Wang, S, Wu, W, Mondal, AK, Wang, C & Wang, G 2018, 'A novel lithium-ion hybrid capacitor based on an aerogel-like MXene wrapped Fe2O3nanosphere anode and a 3D nitrogen sulphur dual-doped porous carbon cathode', Materials Chemistry Frontiers, vol. 2, no. 10, pp. 1811-1821.
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A novel lithium-ion hybrid capacitor was assembled based on an aerogel-like Ti3C2Tx@Fe2O3anode and a 3-D dual-doped porous carbon cathode.
Tang, X, Liu, H, Su, D, Notten, PHL & Wang, G 2018, 'Hierarchical sodium-rich Prussian blue hollow nanospheres as high-performance cathode for sodium-ion batteries', Nano Research, vol. 11, no. 8, pp. 3979-3990.
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© 2018, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature. Recently, Prussian blue and its analogues (PBAs) have attracted tremendous attention as cathode materials for sodium-ion batteries because of their good cycling performance, low cost, and environmental friendliness. However, they still suffer from kinetic problems associated with the solid-state diffusion of sodium ions during charge and discharge processes, which leads to low specific capacity and poor rate performances. In this work, novel sodium iron hexacyanoferrate nanospheres with a hierarchical hollow architecture have been fabricated as cathode material for sodium-ion batteries by a facile template method. Due to the unique hollow sphere morphology, sodium iron hexacyanoferrate nanospheres can provide large numbers of active sites and high diffusion dynamics for sodium ions, thus delivering a high specific capacity (142 mAh/g), a superior rate capability, and an excellent cycling stability. Furthermore, the sodium insertion/extraction mechanism has been studied by in situ X-ray diffraction, which provides further insight into the crystal structure change of the sodium iron hexacyanoferrate nanosphere cathode material during charge and discharge processes.
Thummavichai, K, Wang, N, Cheong Lem, L, Phillips, M, Ton-That, C, Chang, H, Hu, C, Xu, F, Xia, Y & Zhu, Y 2018, 'Lanthanide-doped W 18 O 49 nanowires: Synthesis, structure and optical properties', Materials Letters, vol. 214, pp. 232-235.
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© 2017 The effects of Ce- and La-doped WOx nanostructures on the morphology and crystal structures of WOx nanowires are investigated first, then the impact of these dopants on the cathodoluminescence (CL) properties of the WOx nanowires is studied. The dopants induced a morphological evolution and crystalline lattice expansion of the WOx nanostructures. By analyzing the surface composition and oxidation state ratios of W5+/W6+ in each sample using X-ray photoelectron spectroscopy, we attempt to interpret the observed CL spectra shift from ultraviolet to blue emission of the Ce- and La-doped nanowires.
Tian, H, Huang, F, Zhu, Y, Liu, S, Han, Y, Jaroniec, M, Yang, Q, Liu, H, Lu, GQM & Liu, J 2018, 'The Development of Yolk–Shell‐Structured Pd&ZnO@Carbon Submicroreactors with High Selectivity and Stability', Advanced Functional Materials, vol. 28, no. 32, pp. 1801737-1801737.
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AbstractDesign of multicomponent yolk–shell structures is crucial for the fabrication of micro/nanoreactors for a variety of applications. This work reports the rational design and synthesis of yolk–shell‐structured submicroreactors with loaded metal nanoparticles into ZnO–microporous carbon core–shell structures. The solvothermal treatment and carbonization process of uniform zeolitic imidazolate framework‐8 (ZIF‐8)@resin polymer core–shell structures leads to the generation of yolk–shell‐structured ZnO@carbon. The synthesis conditions are optimized to track the evolution of ZIF‐8 in a confined space of resin polymer as a submicroreactor itself. It is found that nanoribbon evolution occurs via the formation of the intermediate needle‐like particles. The Pd&ZnO@carbon submicroreactor is shown to be a highly selective catalyst (selectivity >99%) for hydrogenation of phenylacetylene to phenylethylene. The excellent performance of Pd&ZnO@carbon particles is evidenced by higher conversion and selectivity than that of Pd/ZnO and Pd/C with similar Pd loading. Furthermore, Pd&ZnO@carbon submicroreactors show superior catalytic stability, and no deactivation after 25 h of reaction. The proposed strategy is promising for the design of multifunctional micro/nanoreactors or nanocontainers for construction of artificial cells.
Tian, H, Wang, T, Zhang, F, Zhao, S, Wan, S, He, F & Wang, G 2018, 'Tunable porous carbon spheres for high-performance rechargeable batteries', Journal of Materials Chemistry A, vol. 6, no. 27, pp. 12816-12841.
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A review focusing on the tunable pore structure design, surface chemistry, composition, and electrochemical performances of PCSs in various types of rechargeable batteries in order to provide insight and inspiration for promoting the development of next-generation high-performance batteries.
Toole, K, Philp, M, Krayem, N, Fu, S, Shimmon, R & Taflaga, S 2018, 'Color Tests for the Preliminary Identification of New Psychoactive Substances', Methods in molecular biology (Clifton, N.J.), vol. 1810, pp. 1-11.
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Color tests are a key tool for the rapid and simple identification of seized illicit drugs. This chapter outlines a series of color tests that can be used for the preliminary identification of new psychoactive substances such as cathinones, piperazines, tryptamines, and amphetamine-type stimulants.
van Zyl, VL, Muller, A & Williams, DBG 2018, 'Charge-tagged polar phosphine ligands in Pd-catalysed reactions in aqueous and ionic media', Tetrahedron Letters, vol. 59, no. 10, pp. 918-921.
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© 2018 Elsevier Ltd A new range of polar imidazolium and phosphate-containing ligands was synthesised from readily available starting materials in high yielding multi-step transformations. These ligands were used to generate Pd catalysts for Suzuki and Heck C–C coupling reactions in organic and organic/aqueous media. The catalysts performed well in aqueous media in the Suzuki reaction and less well in the Heck reaction, related to substrate solubility in the aqueous media. When moving to ionic liquids, the Heck reaction dramatically improved, especially in media compatible with the polar catalysts and the non-polar reagents. In all cases, the catalysts were stable to the formation of Pd black, a form of degradation that frequently befalls Pd catalysts. The catalysts could be successfully recycled without loss of activity.
Wang, J & Zhu, J 2018, 'A Simple Method for Performance Prediction of Permanent Magnet Eddy Current Couplings Using a New Magnetic Equivalent Circuit Model', IEEE Transactions on Industrial Electronics, vol. 65, no. 3, pp. 2487-2495.
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© 1982-2012 IEEE. A simple and practical magnetic equivalent circuit (MEC) based analytical technique for calculating the performance parameters of the permanent magnet (PM) eddy current coupling is presented. In the proposed MEC model built with the lumped parameters, the eddy current effects are inherently taken into account by introducing a branch magnetic circuit allowing for the magnetomotive force and the reaction magnetic flux. A complete formulation for the reaction flux which is treated as a kind of leakage flux is derived. A verification process is conducted and it is shown that in a considerably wide range of slip speeds, the torques predicted by the presented method match well with those obtained by both the three-dimensional finite element analysis and experimental measurement. The new MEC-based method also proves to be effective in the performance simulation of the PM eddy current coupling with different design parameters. In addition, the limitation of the proposed approach is also discussed and the reasons are fully investigated.
Wang, S, Liu, S, Li, X, Li, C, Zang, R, Man, Z, Wu, Y, Li, P & Wang, G 2018, 'SnS2/Sb2S3 Heterostructures Anchored on Reduced Graphene Oxide Nanosheets with Superior Rate Capability for Sodium‐Ion Batteries', Chemistry – A European Journal, vol. 24, no. 15, pp. 3873-3881.
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AbstractTin disulfide, as a promising high‐capacity anode material for sodium‐ion batteries, exhibits high theoretical capacity but poor practical electrochemical properties due to its low electrical conductivity. Constructing heterostructures has been considered to be an effective approach to enhance charge transfer and ion‐diffusion kinetics. In this work, composites of SnS2/Sb2S3 heterostructures with reduced graphene oxide nanosheets were synthesized by a facile one‐pot hydrothermal method. When applied as anode material in sodium‐ion batteries, the composite showed a high reversible capacity of 642 mA h g−1 at a current density of 0.2 A g−1 and good cyclic stability without capacity loss in 100 cycles. In particular, SnS2/Sb2S3 heterostructures exhibited outstanding rate performance with capacities of 593 and 567 mA h g−1 at high current densities of 2 and 4 A g−1, respectively, which could be ascribed to the dramatically improved Na+ diffusion kinetics and electrical conductivity.
Wang, T, Su, D, Shanmukaraj, D, Rojo, T, Armand, M & Wang, G 2018, 'Electrode Materials for Sodium-Ion Batteries: Considerations on Crystal Structures and Sodium Storage Mechanisms', Electrochemical Energy Reviews, vol. 1, no. 2, pp. 200-237.
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Abstract: Sodium-ion batteries have been emerging as attractive technologies for large-scale electrical energy storage and conversion, owing to the natural abundance and low cost of sodium resources. However, the development of sodium-ion batteries faces tremendous challenges, which is mainly due to the difficulty to identify appropriate cathode materials and anode materials. In this review, the research progresses on cathode and anode materials for sodium-ion batteries are comprehensively reviewed. We focus on the structural considerations for cathode materials and sodium storage mechanisms for anode materials. With the worldwide effort, high-performance sodium-ion batteries will be fully developed for practical applications. Graphical Abstract: [Figure not available: see fulltext.]
Wang, Y, Fan, S, Wu, S, Wang, C, Huang, Z & Zhang, L 2018, 'In Situ Synthesis and Unprecedented Electrochemical Performance of Double Carbon Coated Cross-Linked Co3O4', ACS Applied Materials & Interfaces, vol. 10, no. 49, pp. 42372-42379.
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© 2018 American Chemical Society. Improving the structural stability and the electron/ion diffusion rate across whole electrode particles is crucial for transition metal oxides as next-generation anodic materials in lithium-ion batteries. Herein, we report a novel structure of double carbon-coated Co 3 O 4 cross-linked composite, where the Co 3 O 4 nanoparticle is in situ covered by nitrogen-doped carbon and further connected by carbon nanotubes (Co 3 O 4 NP@NC@CNTs). This double carbon-coated Co 3 O 4 NP@NC@CNTs framework not only endows a porous structure that can effectively accommodate the volume changes of Co 3 O 4, but also provides multidimensional pathways for electronic/ionic diffusion in and among the Co 3 O 4 NPs. Electrochemical kinetics investigation reveals a decreased energy barrier for electron/ion transport in the Co 3 O 4 NP@NC@CNTs, compared with the single carbon-coated Co 3 O 4 NP@NC. As expected, the Co 3 O 4 NP@NC@CNT electrode exhibits unprecedented lithium storage performance, with a high reversible capacity of 1017 mA h g -1 after 500 cycles at 1 A g -1 , and a very good capacity retention of 75%, even after 5000 cycles at 15 A g -1 . The lithiation/delithiation process of Co 3 O 4 NP@NC@CNTs is dominated by the pseudocapacitive behavior, resulting in excellent rate performance and durable cycle stability.
Wang, Y, Wang, R, Zhou, Y, Huang, Z, Wang, J & Jiang, L 2018, 'Directional Droplet Propulsion on Gradient Boron Nitride Nanosheet Grid Surface Lubricated with a Vapor Film below the Leidenfrost Temperature', ACS Nano, vol. 12, no. 12, pp. 11995-12003.
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© Copyright 2018 American Chemical Society. Controlled propulsion of liquid droplets on a solid surface offers important applications in various fields, including fog harvesting, heat transfer, microfluidics, and microdevice technologies. The propulsion of the liquid droplet is realized only if the driven force exceeds the resistance force. Sometimes the directional propulsion of droplets only takes place at the Leidenfrost state to achieve enough lubrication for a vapor cushion. The thick vapor cushions levitate liquid droplets to reduce resistance force. However, it is still challenging to reduce the vapor cushion thickness and simultaneously realize the directional droplet's motion, especially below the Leidenfrost temperature. Here, a structurally hydrophobic boron nitride nanosheet (BNNS) grid surface was constructed with a two-direction topographical gradient, i.e., the perpendicular altitude gradient and the horizontal density gradient. The polar nature of the B-N bonds results in intrinsic hydrophilicity of the boron nitride layer, which increases the Leidenfrost point and facilitates wetting even at high temperature. Much thinner vapor-lubricating layers are competent in the droplet's directional motion below the Leidenfrost temperature of the BNNS grid surface because the air gap trapped within boron nitride nanosheet grids acts as a part of the lubrication layer.
Watanabe, S, Kuzhiumparambil, U & Fu, S 2018, 'In vitro metabolism of synthetic cannabinoid AM1220 by human liver microsomes and Cunninghamella elegans using liquid chromatography coupled with high resolution mass spectrometry', Forensic Toxicology, vol. 36, no. 2, pp. 435-446.
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© 2018, The Author(s). Purpose: Identifying intake of synthetic cannabinoids generally requires the metabolism data of the drugs so that appropriate metabolite markers can be targeted in urine testing. However, the continuous appearance of new cannabinoids during the last decade has made it difficult to keep up with all the compounds including {1-[(1-methylpiperidin-2-yl)methyl]-1H-indol-3-yl}(naphthalen-1-yl)methanone (AM1220). In this study, metabolism of AM1220 was investigated with human liver microsomes and the fungus Cunninghamella elegans. Methods: Metabolic stability of AM1220 was analysed by liquid chromatography–tandem mass spectrometry in multiple reaction monitoring mode after 1 µM incubation in human liver microsomes for 30 min. Tentative structure elucidation of metabolites was performed on both human liver microsome and fungal incubation samples using liquid chromatography–high-resolution mass spectrometry. Results: Half-life of AM1220 was estimated to be 3.7 min, indicating a high clearance drug. Nine metabolites were detected after incubating human liver microsomes while seven were found after incubating Cunninghamella elegans, leading to 11 metabolites in total (five metabolites were common to both systems). Demethylation, dihydrodiol formation, combination of the two, hydroxylation and dihydroxylation were the observed biotransformations. Conclusions: Three most abundant metabolites in both human liver microsomes and Cunninghamella elegans were desmethyl, dihydrodiol and hydroxy metabolites, despite different isomers of dihydrodiol and hydroxy metabolites in each model. These abundant metabolites can potentially be useful markers in urinalysis for AM1220 intake.
Watanabe, S, Kuzhiumparambil, U & Fu, S 2018, 'Structural Elucidation of Metabolites of Synthetic Cannabinoid UR-144 by Cunninghamella elegans Using Nuclear Magnetic Resonance (NMR) Spectroscopy', The AAPS Journal, vol. 20, no. 2.
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© 2018, American Association of Pharmaceutical Scientists. The number of new psychoactive substances keeps on rising despite the controlling efforts by law enforcement. Although metabolism of the newly emerging drugs is continuously studied to keep up with the new additions, the exact structures of the metabolites are often not identified due to the insufficient sample quantities for techniques such as nuclear magnetic resonance (NMR) spectroscopy. The aim of the study was to characterise several metabolites of the synthetic cannabinoid (1-pentyl-1H-indol-3-yl) (2,2,3,3-tetramethylcyclopropyl) methanone (UR-144) by NMR spectroscopy after the incubation with the fungus Cunninghamella elegans. UR-144 was incubated with C. elegans for 72 h, and the resulting metabolites were chromatographically separated. Six fractions were collected and analysed by NMR spectroscopy. UR-144 was also incubated with human liver microsomes (HLM), and the liquid chromatography-high resolution mass spectrometry analysis was performed on the HLM metabolites with the characterised fungal metabolites as reference standards. Ten metabolites were characterised by NMR analysis including dihydroxy metabolites, carboxy and hydroxy metabolites, a hydroxy and ketone metabolite, and a carboxy and ketone metabolite. Of these metabolites, dihydroxy metabolite, carboxy and hydroxy metabolites, and a hydroxy and ketone metabolite were identified in HLM incubation. The results indicate that the fungus is capable of producing human-relevant metabolites including the exact isomers. The capacity of the fungus C. elegans to allow for NMR structural characterisation by enabling production of large amounts of metabolites makes it an ideal model to complement metabolism studies.
Welford, A, Maniam, S, Gann, E, Thomsen, L, Langford, SJ & McNeill, CR 2018, 'Thionation of naphthalene diimide molecules: Thin-film microstructure and transistor performance', Organic Electronics, vol. 53, pp. 287-295.
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Xiao, L, Alder, R, Mehta, M, Krayem, N, Cavasinni, B, Laracy, S, Cameron, S & Fu, S 2018, 'Development of a quantitative method for the analysis of cocaine analogue impregnated into textiles by Raman spectroscopy', Drug Testing and Analysis, vol. 10, no. 4, pp. 761-767.
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AbstractCocaine trafficking in the form of textile impregnation is routinely encountered as a concealment method. Raman spectroscopy has been a popular and successful testing method used for in situ screening of cocaine in textiles and other matrices. Quantitative analysis of cocaine in these matrices using Raman spectroscopy has not been reported to date. This study aimed to develop a simple Raman method for quantifying cocaine using atropine as the model analogue in various types of textiles. Textiles were impregnated with solutions of atropine in methanol. The impregnated atropine was extracted using less hazardous acidified water with the addition of potassium thiocyanate (KSCN) as an internal standard for Raman analysis. Despite the presence of background matrix signals arising from the textiles, the cocaine analogue could easily be identified by its characteristic Raman bands. The successful use of KSCN normalised the analyte signal response due to different textile matrix background interferences and thus removed the need for a matrix‐matched calibration. The method was linear over a concentration range of 6.25–37.5 mg/cm2 with a coefficient of determination (R2) at 0.975 and acceptable precision and accuracy. A simple and accurate Raman spectroscopy method for the analysis and quantification of a cocaine analogue impregnated in textiles has been developed and validated for the first time. This proof‐of‐concept study has demonstrated that atropine can act as an ideal model compound to study the problem of cocaine impregnation in textile. The method has the potential to be further developed and implemented in real world forensic cases.
Xie, X, Kretschmer, K, Anasori, B, Sun, B, Wang, G & Gogotsi, Y 2018, 'Porous Ti3C2Tx MXene for Ultrahigh-Rate Sodium-Ion Storage with Long Cycle Life', ACS Applied Nano Materials, vol. 1, no. 2, pp. 505-511.
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The development of anode materials remains a challenge to satisfy the requirements of sodium-ion storage for large-scale energy-storage applications, which is ascribed to the low kinetics of ionic/electron transfer of electrode materials. Here we show that the controlled anisotropic assembly of highly conductive Ti3C2Tx MXene nanosheets to form a porous structure can enhance the sodium-ion storage kinetics. At high current densities of 1 and 10 A g-1, the porous Ti3C2Tx electrode delivered capacities of 166 and 124 mA h g-1, respectively. Even at an extremely high current density of 100 A g-1, a capacity of 24 mA h g-1 could be achieved. The porous Ti3C2Tx electrode also exhibited a long cycle life that can be extended to 1000 cycles with no capacity decay at a current density of 1 A g-1. This work demonstrates successful control of the Ti3C2Tx architecture to push electrochemical sodium-ion storage closer to large-scale applications and is expected to shed light on the rational utilization of the outstanding properties of MXenes by controlling their microscopic assembly.
Xiong, P, Zhang, X, Zhang, F, Yi, D, Zhang, J, Sun, B, Tian, H, Shanmukaraj, D, Rojo, T, Armand, M, Ma, R, Sasaki, T & Wang, G 2018, 'Two-Dimensional Unilamellar Cation-Deficient Metal Oxide Nanosheet Superlattices for High-Rate Sodium Ion Energy Storage', ACS Nano, vol. 12, no. 12, pp. 12337-12346.
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Cation-deficient two-dimensional (2D) materials, especially atomically thin nanosheets, are highly promising electrode materials for electrochemical energy storage that undergo metal ion insertion reactions, yet they have rarely been achieved thus far. Here, we report a Ti-deficient 2D unilamellar lepidocrocite-type titanium oxide (Ti0.87O2) nanosheet superlattice for sodium storage. The superlattice composed of alternately restacked defective Ti0.87O2 and nitrogen-doped graphene monolayers exhibits an outstanding capacity of ∼490 mA h g-1 at 0.1 A g-1, an ultralong cycle life of more than 10000 cycles with ∼0.00058% capacity decay per cycle, and especially superior low-temperature performance (100 mA h g-1 at 12.8 A g-1 and -5 °C), presenting the best reported performance to date. A reversible Na+ ion intercalation mechanism without phase and structural change is verified by first-principles calculations and kinetics analysis. These results herald a promising strategy to utilize defective 2D materials for advanced energy storage applications.
Xu, J, Fan, H, Su, D & Wang, G 2018, 'Nitrogen doped yolk-shell carbon spheres as cathode host for lithium-sulfur battery', Journal of Alloys and Compounds, vol. 747, pp. 283-292.
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© 2018 Elsevier B.V. Suppressing the shuttle effect while maintaining high sulfur content is the primary challenge for the development of lithium-sulfur (Li-S) batteries. An effective encapsulator for Li-S battery is supposed to have enough void space for sulfur accommodation and alleviation of volume expansion. Moreover, an excellent electronic conductivity is also crucial for high sulfur utilization. Thus, we designed mesoporous nitrogen doped yolk-shell carbon (NYSC) spheres as novel sulfur encapsulators. This unique structure design greatly fulfills the synergistic effect of chemisorption and physisorption for polysulfides, specially at high sulfur loading. The inner mesoporous “yolk” acts as a sulfur reservoir to entrap polysulfide species. Meanwhile, the outer “shell” serves as a physical barrier to alleviate the dissolution of polysulfides. Additionally, the doped nitrogen atom in carbon lattice can modify the electron distribution, introduce more defects and active sites for the chemisorption of polysulfides, improve the reversibility of Li2S/polysulfide/S conversion and the electronic conductivity, contributing to the enhanced electrochemical performance for Li-S batteries (a high specific capacity of 1329 mA h g−1 at 0.2 C and an extended cycle life).
Xu, J, Lawson, T, Fan, H, Su, D & Wang, G 2018, 'Updated Metal Compounds (MOFs, S, OH, N, C) Used as Cathode Materials for Lithium–Sulfur Batteries', Advanced Energy Materials, vol. 8, no. 10, pp. 1702607-1702607.
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AbstractLithium–sulfur (Li–S) batteries have the potential to be as efficient and as widespread as lithium‐ion (Li‐ion) batteries, since sulfur electrode has high theoretical capacity (1672 mA h gsul−1) and this element is affordable. However, unlike their ubiquitous lithium ion (Li‐ion) counterparts, it is difficult to realize the commercialization of Li‐S battery. Because the shuttle effect of polysulfide inevitably results in the serious capacity degradation. Tremendous progress is devoted to approach this problem from the aspect of physical confinement and chemisorption of polysulfide. Owing to weak intermolecular interactions, physical confinement strategy, however is not effective when the battery is cycled long‐term. Chemisorption of polysulfide that derived from polar–polar interaction, Lewis acid–base interaction, and sulfur‐chain catenation, are proven to significantly suppress the shuttle effect of polysulfide. It is also discovered that the metal compounds have strong chemical interactions with polysulfide. Therefore, this review focuses on latest metal–organic frameworks metal sulfides, metal hydroxides, metal nitrides, metal carbides, and discusses how the chemical interactions couple with the unique properties of these metal compounds to tackle the problem of polysulfide shuttle effect.
Xu, J, Zhang, W, Chen, Y, Fan, H, Su, D & Wang, G 2018, 'MOF-derived porous N–Co3O4@N–C nanododecahedra wrapped with reduced graphene oxide as a high capacity cathode for lithium–sulfur batteries', Journal of Materials Chemistry A, vol. 6, no. 6, pp. 2797-2807.
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N–Co3O4@N–C nanododecahedra combine the advantages of strong affinity for polysulfides and excellent electronic conductivity.
Xu, J, Zhang, W, Fan, H, Cheng, F, Su, D & Wang, G 2018, 'Promoting lithium polysulfide/sulfide redox kinetics by the catalyzing of zinc sulfide for high performance lithium-sulfur battery', Nano Energy, vol. 51, pp. 73-82.
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© 2018 Entrapping polysulfide from dissolution into electrolyte by strong chemisorption of polar materials has been widely reported in lithium-sulfur (Li-S) battery. Here, for the first time, zinc sulfide (ZnS) was demonstrated as an activation catalyst in Li-S battery to suppress the soluble polysulfide shuttle effect by powering kinetics redox reactions of lithium polysulfide/sulfide. Kinetic analyses comprehensively identify that ZnS not only facilities polysulfide redox kinetics in liquid phase (Li2S8→Li2S6→Li2S4), but also promotes the effective decompositions of lithium sulfide (Li2S). Furthermore, first-principle calculations confirm that the low lithium ion diffusion barrier on the surface of ZnS promotes the redox reaction between lithium ion and sulfur species; and the low migration energy barrier of polysulfide on its surface guarantees the fast diffussion of polysulfides from the ZnS surface to the nearby conductive substrate, thus effectively smoothes polysulfides’ entrapping-diffusion-conversion mechanism across the ZnS interface, resulting in the highly reversible electrochemical performance. As evidenced by the ex situ SEM and visible experiment, the reaction between migrated sulfur species and lithium anode was significantly alleviated, and the insulating Li2S/Li2S2 was uniformly deposited on the ZnS-CB/S cathode. This ZnS cathode based Li-S battery exhibits outstanding performance including an excellent retained discharge specific capacity of 589 mA h gsul−1 with the high sulfur loading of 7 mg cm−2 (200 cycles) and extended cycling stability at the high current rate of 2 C, 5 C (632, 388 mA h gsul−1 after 1000 cycles).
Xu, X, Zhou, D, Qin, X, Lin, K, Kang, F, Li, B, Shanmukaraj, D, Rojo, T, Armand, M & Wang, G 2018, 'A room-temperature sodium–sulfur battery with high capacity and stable cycling performance', Nature Communications, vol. 9, no. 1, pp. 3870-3870.
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AbstractHigh-temperature sodium–sulfur batteries operating at 300–350 °C have been commercially applied for large-scale energy storage and conversion. However, the safety concerns greatly inhibit their widespread adoption. Herein, we report a room-temperature sodium–sulfur battery with high electrochemical performances and enhanced safety by employing a “cocktail optimized” electrolyte system, containing propylene carbonate and fluoroethylene carbonate as co-solvents, highly concentrated sodium salt, and indium triiodide as an additive. As verified by first-principle calculation and experimental characterization, the fluoroethylene carbonate solvent and high salt concentration not only dramatically reduce the solubility of sodium polysulfides, but also construct a robust solid-electrolyte interface on the sodium anode upon cycling. Indium triiodide as redox mediator simultaneously increases the kinetic transformation of sodium sulfide on the cathode and forms a passivating indium layer on the anode to prevent it from polysulfide corrosion. The as-developed sodium–sulfur batteries deliver high capacity and long cycling stability.
Yan, K, Sun, B, Munroe, P & Wang, G 2018, 'Three-dimensional pie-like current collectors for dendrite-free lithium metal anodes', Energy Storage Materials, vol. 11, pp. 127-133.
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© 2017 Lithium (Li) metal possesses very high specific capacity and low electrochemical potential, which shows great advantages to be used in next generation rechargeable Li metal batteries (LMBs). However, poor cyclability of Li metal anodes caused by inhomogeneous and uncontrolled Li deposition hinders the practical applications of rechargeable LMBs. Here, in order to effectively suppress Li dendrite growth without degrading the specific capacity, a three-dimensional (3D) pie-like porous current collector was prepared based on copper nanowires (CuNWs) and graphene (GE). The inter-spaces inside the CuNWs framework efficiently accommodate Li deposition. Meanwhile, the GE layer wrapped outside CuNWs functions as flexible interfacial protective layer that could protect extra Li deposition. Furthermore, the GE shell can also decelerate the oxidation of CuNWs in ambient atmosphere. The CuNWs@GE current collectors demonstrated several merits to achieve better Li metal anodes with significantly improved Coulombic efficiency and cyclability for rechargeable LMBs.
Yang, W, Yang, W, Sun, B, Di, S, Yan, K, Wang, G & Shao, G 2018, 'Mixed Lithium Oxynitride/Oxysulfide as an Interphase Protective Layer To Stabilize Lithium Anodes for High-Performance Lithium–Sulfur Batteries', ACS Applied Materials & Interfaces, vol. 10, no. 46, pp. 39695-39704.
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Copyright © 2018 American Chemical Society. Lithium metal is strongly recognized as a promising anode material for next-generation high-energy-density systems. However, unstable solid electrolyte interphase and uncontrolled lithium dendrites growth induce severe capacity decay and short cycle life accompanied by high security risks. Here, we propose a simple method for constructing an artificial solid electrolyte interphase layer on the surface of lithium metal through spontaneous reaction, where ammonium persulfate and lithium nitrate are exploited as oxidants. The satisfactory artificial protective layer with uniform and dense morphology is composed of mixed lithium compounds, mainly including LixSOy and LixNOy species, which could effectively stabilize the interphase between electrolyte and lithium metal anode and restrain the 'shuttle effect' of polysulfides. By employing the premodified lithium metal as anodes for lithium-sulfur batteries, the resulting cells exhibit excellent cycle stability (capacity decay of 0.09% per cycle over 300 cycles at 1 C and Coulombic efficiency of over 98%) and outstanding rate capability (850.8 mAh g-1 even at 4 C). Hence, introducing a stable artificial protective layer to protect lithium anode delivers a new strategy for solving the issues related to lithium-metal batteries.
Yang, Z, Li, P, McDonagh, A, Li, S, Lv, M, Li, Y, Yu, Z & Feng, C 2018, 'Chitosan-based Nano-biocomposites and their Applications in Medicine and Pharmaceutics', Current Organic Chemistry, vol. 22, no. 7, pp. 628-640.
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© 2018 Bentham Science Publishers. Background: Chitosan-based nano-biocomposite has received more and more attentions in the past few years because of the outstanding merits that chitosan is a natural polymer with biodegradable and biocompatible. Objective: The purpose of the present study is to summarize the different preparation methods of chitosan-based nano-biocomposites, such as electrostatic interaction method, preparation of chitosan-based nano-biocomposites from modified chitosan using selfassembly technique, chemical crosslinking approach, metal ions coordination and metal nanoparticles compound methods. In addition, the applications of chitosan-based nanobiocomposites in wound dressing, drug delivery, tissue engineering and biosensors are also discussed. Results: The results show that chitosan-based nano-biocomposites based on nanoparticles or nanohydrogel that can deliver drugs directly to cancer cells at a sustained and controlled rate may provide better efficacy and lower toxicity for the treatment of cancer. Furthermore, chitosan-based nano-biocomposites can enhance the properties of unmodified chitosan and improve the amphipathy, physical and mechanical properties of chitosan and produce new biological functions. Conclusion: It is believed that the rapid development of nano-science and technology must brought broad application prospects for the chitosan-based nano-biocomposites.
Yousaf, M, Wang, Y, Chen, Y, Wang, Z, Aftab, W, Mahmood, A, Wang, W, Guo, S & Han, RPS 2018, 'Tunable Free-Standing Core–Shell CNT@MoSe2 Anode for Lithium Storage', ACS Applied Materials & Interfaces, vol. 10, no. 17, pp. 14622-14631.
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Zhang, J, Zhao, Y, Guo, X, Chen, C, Dong, C-L, Liu, R-S, Han, C-P, Li, Y, Gogotsi, Y & Wang, G 2018, 'Single platinum atoms immobilized on an MXene as an efficient catalyst for the hydrogen evolution reaction', Nature Catalysis, vol. 1, no. 12, pp. 985-992.
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© 2018, The Author(s), under exclusive licence to Springer Nature Limited. Single-atom catalysts offer a pathway to cost-efficient catalysis using the minimal amount of precious metals. However, preparing and keeping them stable during operation remains a challenge. Here we report the synthesis of double transition metal MXene nanosheets—Mo 2 TiC 2 T x , with abundant exposed basal planes and Mo vacancies in the outer layers—by electrochemical exfoliation, enabled by the interaction between protons and the surface functional groups of Mo 2 TiC 2 T x . The as-formed Mo vacancies are used to immobilize single Pt atoms, enhancing the MXene’s catalytic activity for the hydrogen evolution reaction. The developed catalyst exhibits a high catalytic ability with low overpotentials of 30 and 77 mV to achieve 10 and 100 mA cm −2 and a mass activity about 40 times greater than the commercial platinum-on-carbon catalyst. The strong covalent interactions between positively charged Pt single atoms and the MXene contribute to the exceptional catalytic performance and stability.
Zhang, Q, Yan, D, Nie, Z, Qiu, X, Wang, S, Yuan, J, Su, D, Wang, G & Wu, Z 2018, 'Iron-Doped NiCoP Porous Nanosheet Arrays as a Highly Efficient Electrocatalyst for Oxygen Evolution Reaction', ACS Applied Energy Materials, vol. 1, no. 2, pp. 571-579.
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© 2018 American Chemical Society. There is a great challenge to employ an electrocatalyst that has high efficiency, is earth-abundant, and is a non-noble metal for oxygen evolution reaction (OER). Herein, we reported a low-cost and highly efficient OER catalyst, Fe-doped NiCoP nanosheet arrays in situ grown on nickel foam (NiCoFeP/NF), which was synthesized via a simple and mild hydrothermal and phosphorization method. In 1 M KOH solution, the as-prepared NiCoFeP/NF produces a larger current density of 200 mA·cm-2 at a low overpotential of 271 mV and exhibits a low Tafel slope of 45 mV·dec-1, which is superior to commercial RuO2. The outstanding OER performance of the as-prepared NiCoFeP/NF can be attributed to the synergetic effects among Fe, Ni, and Co elements, unique nanosheet arrays structure, and the great intrinsic electrocatalytic activity. On the basis of the above factors, the as-prepared NiCoFeP/NF may work as a promising OER electrocatalyst.
Zhao, S, Sun, B, Yan, K, Zhang, J, Wang, C & Wang, G 2018, 'Aegis of Lithium-Rich Cathode Materials via Heterostructured LiAlF4 Coating for High-Performance Lithium-Ion Batteries', ACS Applied Materials & Interfaces, vol. 10, no. 39, pp. 33260-33268.
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Lithium-rich oxides have been regarded as one of the most competitive cathode materials for next-generation lithium-ion batteries due to their high theoretical specific capacity and high discharge voltage. However, they are still far from being commercialized due to low rate capability and poor cycling stability. In this study, we propose a heterostructured LiAlF4 coating strategy to overcome those obstacles. The as-developed lithium-rich cathode material shows outstanding performance including a high reversible capacity (246 mA h g-1 at 0.1C), excellent rate capability (133 mA h g-1 at 5C), and ultralong cycling stability (3000 cycles). Comparing with those of pristine and AlF3-coated lithium-rich cathode materials, the enhanced performances can be attributed to the introduction of the lithium-ion-conductive nanolayer and the generation of nonbonding O n- species in the active material lattice, which enable rapid and effective lithium ion transport and diffusion. Our work provides a new strategy to develop high-performance lithium-rich cathode materials for high-energy-density lithium-ion batteries.
Zhao, Y, Zhang, J, Wu, W, Guo, X, Xiong, P, Liu, H & Wang, G 2018, 'Cobalt-doped MnO2 ultrathin nanosheets with abundant oxygen vacancies supported on functionalized carbon nanofibers for efficient oxygen evolution', Nano Energy, vol. 54, pp. 129-137.
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© 2018 Elsevier Ltd Developing low-cost and efficient catalysts for oxygen evolution reactions (OER) with both excellent activity and robust stability remains a great challenge. Herein, we report a facile spontaneous redox reaction to grow cobalt-doped MnO2 ultrathin nanosheets in situ with abundant oxygen vacancies vertically aligned on cobalt/nitrogen co-functionalized carbon nanofibers (Co-MnO2|OV) as an efficient OER catalyst. It is confirmed that metallic cobalt plays a critical role in the formation of long and ultrathin MnO2 nanosheets during the redox reaction. Furthermore, the cobalt ions doped into MnO2 significantly enhance the catalytic activity of MnO2 nanosheets. Benefiting from the collaborative advantages of doping strategy, fast charge transfer kinetics and strong synergistic coupling effects, Co-MnO2|OV composites exhibit an excellent catalytic activity and a good durability for electrochemical water oxidation, reaching 10 mA cm−2 at an overpotential of 279 mV. According to the density functional theory (DFT) calculations, the enhanced catalytic activity mainly originates from a better conductivity and the decreased adsorption energy barrier of OH- on the O sites neighboring the doped Co and oxygen vacancies. Our findings suggest that the control over the structure and composition of the materials can achieve highly efficient oxygen evolution electrocatalysts.
Zheng, L, Zhu, J, Lu, DD-C, Wang, G & He, T 2018, 'Incremental capacity analysis and differential voltage analysis based state of charge and capacity estimation for lithium-ion batteries', Energy, vol. 150, pp. 759-769.
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© 2018 Elsevier Ltd The reliability and safety of battery operations necessitate an efficient battery management system (BMS) with accurate battery state of charge (SOC) and capacity estimation techniques. This paper investigates the incremental capacity analysis (ICA) and differential voltage analysis (DVA) methods for onboard battery SOC and capacity estimation. Since the conventional cell terminal voltage based ICA/DVA methods are sensitive to the changed battery resistance and polarization during battery aging processes, the SOC based ICA/DVA methods are proposed to address this problem as so to accurately identify features of interest on incremental capacity (IC) and differential voltage (DV) curves for applications. Three feature points (FPs) that are potential to be easily identified by battery management systems are extracted from the SOC based IC/DV curves, and then the relations between FPs and cell SOCs/capacities are quantified and applied for battery SOC and capacity estimation. The robustness of the proposed approach against various aging levels and erroneous cumulative capacities is evaluated. Promising results with the maximum absolute error of 1.0% and the relative error of 2.0% can be achieved for battery SOC and capacity estimation, respectively.
Zheng, L, Zhu, J, Wang, G, Lu, DD-C & He, T 2018, 'Differential voltage analysis based state of charge estimation methods for lithium-ion batteries using extended Kalman filter and particle filter', Energy, vol. 158, pp. 1028-1037.
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© 2018 Elsevier Ltd Accurate battery state of charge (SOC) estimation can contribute to safe and reliable utilization of the battery. However, commonly used battery model-based SOC estimation methods suffer from the lack of a universal battery model for cells in a battery pack since the model parameters of each cell are inevitably different from each other and variable with battery aging, leading to difficulties in promoting the model-based methods for real applications. To solve this problem, a differential voltage (DV) analysis based universal battery model and two associated SOC estimation algorithms using extended Kalman filter (EKF) and particle filter (PF), respectively, are proposed in this paper. By means of a natural cubic interpolation approach, a battery SOC-DV model is firstly derived from the SOC based DV curves of various cells at different aging levels. A novel battery model-based scheme is then proposed to incorporate the SOC-DV model for the estimation. The robustness of the proposed approaches against different cell aging levels is evaluated, and the promising SOC estimates with the maximum absolute error of 1.75% and the root mean square error of less than 1.10% can be achieved.
Zheng, L, Zhu, J, Wang, G, Lu, DD-C & He, T 2018, 'Lithium-ion Battery Instantaneous Available Power Prediction Using Surface Lithium Concentration of Solid Particles in a Simplified Electrochemical Model', IEEE Transactions on Power Electronics, vol. 33, no. 11, pp. 9551-9560.
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© 1986-2012 IEEE. Accurate battery power capability prediction can contribute to reliable and sufficient utilization of the battery to absorb or deliver a certain amount of power within its safe operating area. The power capability of a battery is a finite quantity that is limited by the electrochemical reaction properties occurring inside the battery. Note that the instantaneous available power of the battery is strongly related to the surface lithium concentration of solid particles in battery electrodes, but their relationship has not been explored sufficiently yet. This paper proposes a novel method for battery instantaneous available power prediction using a practical physical limit (i.e., lithium concentration limit) rather than the limits of macroscopically observed variables, such as the cell terminal voltage and current, thus providing a direct insight into electrochemical processes inside batteries. The surface lithium concentration of the solid particle is derived from a simplified battery electrochemical model, and a relationship between battery instantaneous available power and surface lithium concentration is quantified for the power capability prediction. Promising results with small forecast errors can be achieved for battery charging and discharging at different cell aging levels and ambient temperatures, which highlights the superior accuracy and robustness of the proposed method.
Zhu, L, Lockrey, M, Phillips, MR & Ton‐That, C 2018, 'Spatial Distribution of Defect Luminescence in ZnO Nanorods: An Investigation by Spectral Cathodoluminescence Imaging', physica status solidi (a), vol. 215, no. 19, pp. 1800389-1800389.
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The spatial distribution of ubiquitous green luminescence (GL) in ZnO nanorods is investigated using cathodoluminescence (CL) spectral imaging. The vertically aligned, single‐crystal nanorods exhibit a strong GL emission at 2.42 eV at 80 K, attributable to oxygen vacancies. The spectral imaging reveals the GL emission is predominantly located in the surface layer of nanorods; the thickness and intensity of this layer decreases rapidly at elevated temperatures. On the other hand, the near‐band‐edge emission is weakest near the nanorod edges. The temperature‐dependent CL maps are consistent with the properties of a model in which singly ionized oxygen vacancies are stabilized by the surface band bending, which leads to the GL enhancement at the expense of near‐band‐edge emission. These results demonstrate the utility of spectral CL imaging to map the spatial distribution of defect luminescence in nanostructured materials.
Zhu, X, Mochiku, T, Fujii, H, Tang, K, Hu, Y, Huang, Z, Luo, B, Ozawa, K & Wang, L 2018, 'A new sodium iron phosphate as a stable high-rate cathode material for sodium ion batteries', Nano Research, vol. 11, no. 12, pp. 6197-6205.
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© 2018, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature. Low-cost room-temperature sodium-ion batteries (SIBs) are expected to promote the development of stationary energy storage applications. However, due to the large size of Na+, most Na+ host structures resembling their Li+ counterparts show sluggish ion mobility and destructive volume changes during Na ion (de)intercalation, resulting in unsatisfactory rate and cycling performances. Herein, we report a new type of sodium iron phosphate (Na0.71Fe1.07PO4), which exhibits an extremely small volume change (~ 1%) during desodiation. When applied as a cathode material for SIBs, this new phosphate delivers a capacity of 78 mA·h·g−1 even at a high rate of 50 C and maintains its capacity over 5,000 cycles at 20 C. In situ synchrotron characterization disclosed a highly reversible solid-solution mechanism during charging/discharging. The findings are believed to contribute to the development of high-performance batteries based on Earth-abundant elements. [Figure not available: see fulltext.].
Zou, J, Xu, W, Zhu, J & Liu, Y 2018, 'Low-Complexity Finite Control Set Model Predictive Control With Current Limit for Linear Induction Machines', IEEE Transactions on Industrial Electronics, vol. 65, no. 12, pp. 9243-9254.
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© 1982-2012 IEEE. In order to limit the armature current within a safe region, this paper proposes a finite control set model predictive control (FCS-MPC) method for linear induction machines (LIMs) by adding a penalty overcurrent term in the cost function. The modulation strategies based on two and three voltage vectors are combined with FCS-MPC so as to reduce the current ripples and steady-state tracking errors. Three different search methods have been developed to help reduce the computational burden by excluding many unsuitable participating voltage vectors and combinations in advance. These search methods are also effective for FCS-MPC with current limit. Finally, some key performance indexes are fully compared for LIMs controlled by different FCS-MPC-based modulation strategies through comprehensive numerical simulation and experiments on a test bench with two 3-kW arc induction motors. It is shown that the proposed low-complexity control strategies can effectively avoid overcurrent under any circumstances.
