CuO/graphene composite is synthesized from CuO and graphene oxide sheets following reduced by hydrazine vapor. As the electrode material for lithium-ion batteries, CuO nanoparticles with sizes of ...about 30nm homogeneously locate on graphene sheets, and act as spacers to effectively prevent the agglomeration of graphene sheets, keeping their high active surface. In turn, the graphene sheets with good electrical conductivity server as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during discharge/charge process. The synergetic effect is beneficial for the electrochemical performances of CuO/graphene composite, such as improved initial coulombic efficiency (68.7%) and reversible capacity of 583.5mAhg−1 with 75.5% retention of the reversible capacity after 50 cycles.
Relatively small hysteresis in voltage, appropriate electromotive force and low average delithiation voltage make MnO, among many transition metal oxides. MnO/reduced graphene oxide sheet (MnO/RGOS) ...hybrid is synthesized by a two-step electrode design consisting of liquid phase deposition of MnCO3 nanoparticles on the surface of graphene oxide sheets followed by heat treatment in flowing nitrogen. As an anode for Li-ion batteries, the MnO/RGOS hybrid electrode shows a reversible capacity of 665.5 mA h g−1 after 50 cycles at a current density of 100 mA g−1 and delivers 454.2 mA h g−1 at a rate of 400 mA g−1, which is obviously better than that of bare MnO electrode. Those reasons for such enhanced electrochemical properties are investigated by galvanostatic intermittent titration technique (GITT) as well as electrochemical impedance spectroscopy (EIS). The probable origins, in the term of thermodynamic and kinetic factors, for the marked hysteresis in voltage observed between charge and discharge are also discussed.
► MnO/RGOS hybrid is synthesized by a two-step electrode design. ► As an anode material, it displays superior lithium storage performance. ► Reasons for such enhanced performance are investigated by TEM, GITT and EIS. ► The probable origins of hysteresis in voltage are discussed.
A better understanding of plant cell micromechanics would enhance the current opinion on "how things are happening" inside a plant cell, enabling more detailed insights into plant physiology as well ...as processing plant biomaterials. However, with the contemporary laboratory equipment, the experimental investigation of cell micromechanics has been a challenging task due to diminutive spatial and time scales involved. In this investigation, a three-dimensional (3-D) coupled Smoothed Particle Hydrodynamics (SPH) and Coarse-Grained (CG) computational approach has been employed to model micromechanics of single plant cells going through drying or dehydration. This meshfree-based computational model has conclusively demonstrated that it can effectively simulate the behaviour of stress and strain in a plant cell being compressed at different levels of dryness: ranging from a fresh state to an extremely dried state. In addition, different biological and physical circumstances have been approximated through the proposed novel computational framework in the form of different turgor pressures, strain rates, mechanical properties and cell sizes. The proposed computational framework has potential not only to study the micromechanical characteristics of plant cellular structure during drying, but also other equivalent, biological structures and processes with relevant modifications. There are no underlying difficulties in adopting the model to replicate other types of cells and more sophisticated micromechanical phenomena of the cells under different external loading conditions.
•MnCo2O4 nanowire array is prepared by a fast and facile hydrothermal method.•MnCo2O4 nanowire array exhibits noticeable pseudocapacitive properties.•The as-prepared nanowire array is also a ...promising material for Li-ion batteries.
One-dimension MnCo2O4 nanowire arrays are synthesized on nickel foam by a facile hydrothermal method. The MnCo2O4 nanowires are highly crystalline with an average diameter of 70nm and exhibit excellent properties for electrochemical energy storage. Impressively, the MnCo2O4 nanowire array exhibits noticeable pseudocapacitive performance with a high capacitance of 349.8 F g−1 at 1 A g−1 and 328.9 F g−1 at 20 A g−1 as well as excellent cycling stability. As an anode material for Li-ion batteries, the MnCo2O4 nanowire array delivers an initial specific discharge capacity of 1288.6 mAh g−1 at 100mAg−1, with reversible capacity retention of 92.7% after 50 cycles. The outstanding electrochemical performances are mainly attributed to its nanowire array architecture which provides large reaction surface area, fast ion and electron transfer and good structure stability.
The WO3/PANI core/shell nanowire array is prepared by the combination of solvothermal and electropolymerization methods. The core/shell nanowire array film shows remarkable enhancement of the ...electrochromic properties. In particular, a significant optical modulation (59% at 700nm), fast switching speed, high coloration efficiency (86.3cm2C−1 at 700nm) and excellent cycling stability are achieved for the core/shell nanowire array film. The improved electrochromic properties are mainly attributed to the formation of the donor–acceptor system, and the porous space among the nanowires, which can make fast ion diffusion and provide larger surface area for charge-transfer reactions. The data indicate great promise for the WO3/PANI core/shell nanowire array as a potential multicolor electrochromic material.
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•The WO3/PANI core/shell nanowire array is successfully prepared.•The dual-electrochromism effect is obtained for the core/shell nanowire array.•The core/shell structure exhibits large optical modulation and fast switching speed.•High CE and excellent cycling stability are achieved for the core/shell structure.
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Metal-doping is considered to be an effective way for construction of advanced semiconducting metal oxides with tailored physicochemical properties. Herein, Mo-doped WO3 nanowire ...arrays are rationally fabricated by a sulfate-assisted hydrothermal method. Compared to the pure WO3, the optimized Mo-doped WO3 nanowire arrays exhibit improved electrochromic properties with fast switching speed (3.2s and 2.6s for coloration and bleaching, respectively), significant optical modulation (56.7% at 750nm, 83.0% at 1600nm and 48.5% at 10μm), high coloration efficiency (123.5cm2C−1) and excellent cycling stability. In addition, as a proof of concept, the Mo-doped WO3 nanowire arrays are demonstrated with electrochemical energy storage monitored by the electrochromism. This electrode design protocol can provide an alternative way for developing high-performance active materials for bi-functional electrochromic batteries.
Two NiO products with different microstructures have been obtained using a traditional NaOH-induced aqueous-phase precipitation and a homogeneous precipitation in choline chloride/urea mixture-based ...deep eutectic solvent (DES), respectively. The synthesis processes play a key role in the structure construction of NiO precursors as well as the final NiO products, and possible formation mechanisms are proposed. The DES-based homogeneous precipitation method provides plentiful nucleation sites, moderate crystal growth process and possible template effect, which could conduce to the production of flower-like NiO with continuously self-supporting mesoporous structure assembled by tiny grains. The flower-like NiO electrode exhibits higher current density, faster charge-transfer process, better electrode accessibility, and improved stability for methanol electro-oxidation in an electrolyte of 0.1 M CH3OH + 0.005 M KOH than the disorderly aggregated NiO nanoparticles. We believe that the DES-based homogeneous precipitation method can provide an effective approach to fabricate advanced electrocatalyst materials with homogeneous and well-assembled microstructure.
•Synthesis of α-Ni(OH)2 nanostructure by a novel precipitation strategy in ionic liquid.•Annealing the flower-like α-Ni(OH)2 produces mesoporous NiO electrode.•Mesoporous structure of NiO is assembled by ∼5 nm sized grains.•Mesoporous structure is better than nanoparticulate for methanol electro-oxidation.
LiF is successful used to modify the surface of layered LiNi1/3Co1/3Mn1/3O2 via a wet chemical method followed by an annealing process. The lattice structure of LiNi1/3Co1/3Mn1/3O2 is not changed ...distinctly after modification and part of F− dopes into the surface lattice of the oxide. The LiF-modified oxide exhibits capacity retentions of 97.5% at 0.1 C at room temperature and 93.5% at 1 C at 60 °C after 50 cycles, and delivers a high discharge capacity of 137 mAh g−1 at 10 C at room temperature. Furthermore, it has reversible capacities of 124.4 mAh g−1 at 1 C at 0 °C and 85.6 mAh g−1 at 0.1 C at −20 °C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests show that the LiF-modified layer can reduce the dissolution of metal ions in the electrode and enhance the conductivity of the oxide surface through partly F-substitution. LiF modification will be promising for the application of layered oxide for lithium ion batteries.
► LiNi1/3Co1/3Mn1/3O2 is modified with LiF by a wet chemical method. ► Discharge capacity of 137 mAh g−1 is obtained at 10 C (2800 mA g−1). ► Capacity retention of 93.5% is obtained at 1 C at 60 °C after 50 cycles. ► Reversible capacity of 124.4 mAh g−1 is obtained at 1 C at 0 °C. ► Even at −20 °C, discharge capacity of 85.6 mAh g−1 is obtained at 0.1 C.
Numerical modelling has emerged as a powerful and effective tool to study various dynamic behaviours of biological matter. Such numerical modelling tools have contributed to the optimisations of food ...drying parameters leading to higher quality end-products in the field of food engineering. In this context, one of the most recent developments is the meshfree-based numerical models, which have demonstrated enhanced capabilities to model cellular deformations during drying, providing many benefits compared to conventional grid-based modelling approaches. However, the potential extension of this method for simulating bulk level tissues has been a challenge due to the increased requirement for higher computational time and resources. As a solution for this, by incorporating meshfree features, a novel coarse-grained multiscale numerical model is proposed in this work to predict bulk level (macroscale) deformations of food-plant tissues during drying. Accordingly, realistic simulation of morphological changes of apple tissues can now be performed with just 2% of the previous computational time in microscale and macroscale simulations can also be conducted. Compared to contemporary multiscale models, this modelling approach provides more convenient computational implementation as well. Thus, this novel approach can be recommended for efficiently and accurately simulating morphological changes of cellular materials undergoing drying processes, while confirming its potential future expansion to efficiently and accurately predict morphological changes of heterogeneous plant tissues in different spatial scales.
► In this paper, we attempt to address the poor kinetics of conversion reactions, the major drawback for it, by synchronously considering optimization design of electrode configuration and ...improvement of the lattice electronic conductivity of active materials. Results suggest Co-doped NiO nanoflake arrays electrode show high capacity, good cycling performance and rate capability. These can be attributed to the synthesis effect, coming from high electrode–electrolyte contact area, direct contact between each naonflake and current collector, fast Li+ diffusion and improvement of p-type conductivity of active materials.
Co-doped NiO nanoflake arrays with a cellular-like morphology are fabricated by low temperature chemical bath deposition. As anode material for lithium ion batteries (LIBs), the array film shows a capacity of 600mAhg−1 after 50 discharge/charge cycles at low current density of 100mAg−1, and it retains 471mAhg−1 when the current density is increased to 2Ag−1. Appropriate electrode configuration possesses some unique features, including high electrode–electrolyte contact area, direct contact between each naonflake and current collector, fast Li+ diffusion. The Co2+ partially substitutes Ni3+, resulting in an increase of holes concentration, and therefore improved p-type conductivity, which is useful to reduce charge transfer resistance during the charge/discharge process. The synergetic effect of these two parts can account for the improved electrochemical performance.
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