Phase Modulation of (1T-2H)-MoSe2/TiC-C Shell/Core Arrays via Nitrogen Doping for Highly Efficient Hydrogen Evolution Reaction

Tailoring molybdenum selenide electrocatalysts with tunable phase and morphology is of great importance for advancement of hydrogen evolution reaction (HER). In this work, phase‐ and morphology‐modulated N‐doped MoSe2/TiC‐C shell/core arrays through a facile hydrothermal and postannealing treatment strategy are reported. Highly conductive TiC‐C nanorod arrays serve as the backbone for MoSe2 nanosheets to form high‐quality MoSe2/TiC‐C shell/core arrays. Impressively, continuous phase modulation of MoSe2 is realized on the MoSe2/TiC‐C arrays. Except for the pure 1T‐MoSe2 and 2H‐MoSe2, mixed (1T‐2H)‐MoSe2 nanosheets are achieved in the N‐MoSe2 by N doping and demonstrated by spherical aberration electron microscope. Plausible mechanism of phase transformation and different doping sites of N atom are proposed via theoretical calculation. The much smaller energy barrier, longer HSe bond length, and diminished bandgap endow N‐MoSe2/TiC‐C arrays with substantially superior HER performance compared to 1T and 2H phase counterparts. Impressively, the designed N‐MoSe2/TiC‐C arrays exhibit a low overpotential of 137 mV at a large current density of 100 mA cm−2, and a small Tafel slope of 32 mV dec−1. Our results pave the way to unravel the enhancement mechanism of HER on 2D transition metal dichalcogenides by N doping

Micro/Nanobinary Structure of Silver Films on Copper Alloys with Stable Water-Repellent Property under Dynamic Conditions

Facile galvanic replacement was adopted to grow cauliflower-like and dendrite coral-like silver films on commercial copper alloy substrates. Both types of silver films possess micro/nanobinary structures, the formation and evolution of which are achieved through the oriented attachment growth mechanism. After modification by a monolayer of n-dodecanethiol, the cauliflower-like silver film becomes hydrophobic with a contact angle (CA) of 115 +/- 1 degrees and a CA hysteresis of 74 +/- 1 degrees and the dendrite coral-like silver film exhibits the extreme hydrophobicity characterized by a CA of 158 +/- 1 degrees and a CA hysteresis of less than 2 +/- 1 degrees. Furthermore, the bouncing property of millimeter-sized water droplets on the modified dendrite coral-like silver surface is much better than that on the modified cauliflower-like silver surface. The different wetting property between the two silver films is attributed to the surface roughness. Larger surface roughness provided by the dendrite coral-like silver film means more air pockets, among the micro/nanobinary structures, that bounce water droplets back more strongly. The dynamic bouncing behavior of water droplets, such as restitution coefficient and contact time, oil the superhydrophobic modified cauliflower-like silver surface was also investigated at different impact velocities

Phytic-Acid-Modified Copper Foil as a Current Collector for Lithium-Ion Batteries

Electrolytic copper foil is ideal for use in the anode current collectors of lithium-ion batteries (LIBs) because of its abundant reserves, good electrical conductivity, and soft texture. However, electrolytic copper foil is prone to corrosion in electrolytes and weak bonding to the anode substance. Surface modification of copper foil is considered an effective method of improving the overall electrochemical performance of LIBs. In this study, a 5 nm thickness phytic acid (PA)-based film is constructed on electrolytic copper foil using a fast electrodeposition process (about 10 s). PA-treated copper foil (PA-Cu) displays an improved corrosion resistance in electrolytes because of a strong complexation between the PA and copper. It is found that PA-treated copper foil also bonds better with graphite particles compared with pristine copper foil. LIBs with PA-Cu foils as their current collectors exhibit enhanced cycling stability, improved capacity retention, and superior rate performance at both low and high current densities. Our study offers a novel avenue for the development of high-performance electrode current collector materials for LIBs

Integrated carbon nanospheres arrays as anode materials for boosted sodium ion storage

Developing cost-effective advanced carbon anode is critical for innovation of sodium ion batteries. Herein, we develop a powerful combined method for rational synthesis of free-standing binder-free carbon nanospheres arrays via chemical bath plus hydrothermal process. Impressively, carbon spheres with diameters of 150–250 nm are randomly interconnected with each other forming highly porous arrays. Positive advantages including large porosity, high surface and strong mechanical stability are combined in the carbon nanospheres arrays. The obtained carbon nanospheres arrays are tested as anode material for sodium ion batteries (SIBs) and deliver a high reversible capacity of 102 mAh g−1 and keep a capacity retention of 95% after 100 cycles at a current density of 0.25 A g−1 and good rate performance (65 mAh g−1 at a high current density of 2 A g−1). The good electrochemical performance is attributed to the stable porous nanosphere structure with fast ion/electron transfer characteristics

Robust Slippery Coating with Superior Corrosion Resistance and Anti-Icing Performance for AZ31B Mg Alloy Protection

Biomimetic slippery liquid-infused porous surfaces (SLIPSs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and susceptibility to frosting. Herein, we fabricated a double-layered SLIPS coating on the AZ31 Mg alloy for corrosion protection and anti-icing application. The porous top layer was infused by lubricant, and the compact underlayer was utilized as a corrosion barrier. The water-repellent SLIPS coating exhibits a small sliding angle and durable corrosion resistance compared with the SHS coating. Moreover, the SLIPS coating delivers durable anti-icing performance for the Mg alloy substrate, which is obviously superior to the SHS coating. Multiple barriers in the SLIPS coating, including the infused water-repellent lubricant, the self-assembled monolayers coated porous top layer, and the compact layered double hydroxide–carbonate composite underlayer, are suggested as being responsible for the enhanced corrosion resistance and anti-icing performance. The robust double-layered SLIPS coating should be of great importance to expanding the potential applications of light metals and their alloys

Rapid Electrodeposition and Corrosion Behavior of Zn Coating from a Designed Deep Eutectic Solvent

This work aimed to develop a new type of deep eutectic solvent containing high concentrations of zinc ions as an electrolyte to improve the electrodeposition rate for zinc plating. Two typical deep eutectic solvent systems, choline chloride (ChCl)–urea and ChCl–ethylene glycol (EG), were combined to prepare a stable electrolyte at room temperature with a zinc ion concentration up to 2 M. Cyclic voltammetry experiments of the electrolyte at different temperatures were conducted. The effects of key electrodeposition parameters (bath temperature and current density) on the morphology, structure, and corrosion resistance of zinc coatings deposited on mild steel were investigated. It was found that the crystal orientation of the as-deposited zinc particle is related to the electrodeposition temperature and current density. The experimental results show that the zinc coating deposited at 60 °C and the current density of 4 mA·cm−2 exhibited the most compact and crack-free morphology, thus had the optimum corrosion resistance property

An unsymmetric 8‐node plane element immune to mesh distortion for linear isotropic hardening material

An 8-node quadrilateral plane element US-QUAD8 is developed for linear isotropic hardening material in the framework of updated Lagrangian unsymmetric finite formulation where (Formula presented.) matrix is constructed by classical shape function, and (Formula presented.) matrix by the higher-order Lagrangian basis function in global coordinate system. The present element eliminates the influence of Jacobian in the elemental stiffness matrix and guarantees the quadratic completeness of displacement field even under severe distorted mesh. Two typical problems meshed with angular/curved-edge/mid-side distorted elements demonstrate excellent performance of distortion resistance of the present element and good computational efficiency in severe mesh distortion.Ministry of Education (MOE)Submitted/Accepted versionJiangping Xu thanks the starting grant supported by Jiangsu University (Grant number: 19JDG022). Wei Chen thanksthe National Natural Science Foundation of China (Grant number: 51875263). Wenbin Tu thanks the open fund of HubeiKey Laboratory of Mechanical Transmission and Manufacturing Engineering in Wuhan University of Science and Tech-nology (Grant number: 2017A03). Sellakkutti Rajendran thanks the support provided by research grant no. RG 29/08(M52050104) of Academic Research Fund (AcRF) Tier 1, Ministry of Education, Singapore for carrying out this research

Transition Metal Carbides and Nitrides in Energy Storage and Conversion

High-performance electrode materials are the key to advances in the areas of energy conversion and storage (e.g., fuel cells and batteries). In this Review, recent progress in the synthesis and electrochemical application of transition metal carbides (TMCs) and nitrides (TMNs) for energy storage and conversion is summarized. Their electrochemical properties in Li-ion and Na-ion batteries as well as in supercapacitors, and electrocatalytic reactions (oxygen evolution and reduction reactions, and hydrogen evolution reaction) are discussed in association with their crystal structure/morphology/composition. Advantages and benefits of nanostructuring (e.g., 2D MXenes) are highlighted. Prospects of future research trends in rational design of high-performance TMCs and TMNs electrodes are provided at the end.Published versio

A three-dimensional hierarchical Fe2O3@NiO core/shell nanorod array on carbon cloth : a new class of anode for high-performance lithium-ion batteries

A Fe2O3@NiO core/shell nanorod array on carbon cloth was prepared with the aid of hydrothermal synthesis combined with subsequent chemical bath deposition. The resultant array structure is composed of Fe2O3 nanorods as the core and interconnected ultrathin NiO nanoflakes as the shell. As an anode material for lithium-ion batteries, the heterostructured array electrode delivers a high discharge capacity of 1047.2 mA h g−1 after 50 cycles at 200 mA g−1, and 783.3 mA h g−1 at a high current density of 2000 mA g−1. The excellent electrochemical performance is attributed to the unique 3D core/shell nanorod array architecture and a rational combination of two electrochemical active materials. Our growth approach offers a simple and effective technique for the design and synthesis of a transition metal oxide hierarchical array that is promising for high-performance electrochemical energy storage