Stable multi-electron reaction stimulated by W doping VS_(4)for enhancing magnesium storage performance

Rechargeable magnesium batteries(RMBs)hold promise for offering higher volumetric energy density and safety features,attracting increasing research interest as the next post lithium-ion batteries.Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs.Herein,multielectron reaction occurred in VS_(4)by simple W doping strategy.W doping induces valence of partial V as V^(2+)and V^(3+)in VS_(4)structure,and then stimulates electrochemical reaction involving multi-electrons in 0.5%W-V-S.The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process.The fabricated 0.5%W-V-S delivers higher specific capacity(149.3 m A h g^(-1)at 50 m A g^(-1),which is 1.6 times higher than that of VS_(4)),superior rate capability(76 mA h g^(-1)at 1000 mA g^(-1)),and stable cycling performance(1500cycles with capacity retention ratio of 93.8%).Besides that,pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique(GITT)further confirms the enhanced Mg^(2+)storage kinetics during such multi-electron involved electrochemical reaction process.Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.

Impact of W alloying on microstructure, mechanical property and corrosion resistance of face-centered cubic high entropy alloys: A review

Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.

Investigation on Bodily Fault in Doped W Wire by Electronic Miscroscope

The forming process of the bodil y fault in doped W wire was observed by SEM and TEM. The forming kinetics was de scibed by the perturbing theory. The interaction among the bodily fault and the dislocation or the grain boundary was also observed. The strengthen effect cause d by the interaction is counted initially by each submitted probable models. The results show that the strengthening mechanism at middle and high temperature is different.

Diffusion Behavior of Cumulative He Doped in Cu/W Multilayer Nanofilms at Room Temperature

Cu/W multilayer nanofilms are prepared in pure Ar and He/At mixing atmosphere by the rf magnetron sputtering method. The cross-sectional morphology and the defect distribution of the Cu/W multilayer nanofilms are characterized by scanning electron microscopy and Doppler broadening positron annihilation spectroscopy. The results show that plenty of point defects can be produced by introducing He during the growth of the multilayer nanofilms. With the increasing natural storage time, He located in the near surface of the Cu//W multilayer nanofilm at room temperature could be released gradually and induce the segregation of He-related defects due to the diffusion of He and defects. However, more He in the deep region spread along the interface of the Cu/W multilayer nanofilm. Meanwhile, the layer interfaces can still maintain their stability.

Tuning electronic structure of Ni_(3)S_(2) with tungsten doping for high-performance electrooxidation of 5-hydroxymethylfurfural

Electrooxidation of the biomass derivative 5-hydroxymethylfurfural (HMF) is a highly promising approach for attaining versatile value-added chemicals (e.g.,2,5-furandicarboxylic acid,FDCA).Ni-based sulfides are promising electrocatalysts for HMF electrooxidation reaction (HMFOR).However,the HMFOR activity of Ni-based catalysts is far from satisfactory due to the unfavorable adsorption of HMF and OH^(*).Herein,we propose controlled W doping to effectively modify the electronic configuration of nanostructured Ni_(3)S_(2) to manipulate adsorption of HMF and OH^(*),for efficiently converting HMF into FDCA.Experimental and theoretical calculations indicate the incorporation of high-valence W results in the upshift of d-band center of Ni_(3)S_(2),which facilitates the adsorption and dissociation of water to produce more OH^(*).Meanwhile,the high-valence W has strong electron-withdrawing ability and attracts electrons from Ni,leading to the elevated Ni valence,which is beneficial to optimizing the adsorption energy of HMF.Both concurrently contribute to the superb HMFOR performance.As a result,W_(20)-Ni_(3)S_(2)@NF with optimal W dopant exhibits a low driving potential (1.34 V vs.RHE at 10 mA cm^(-2)),accompanying with the 100% HMF conversion,99.2%FDCA selectivity,and 97.3%Faraday efficiency.This work provides a design principle for HMFOR electrocatalysts by modulating the adsorption behaviors of HMF and OH^(*)via rational electronic structure engineering.

Preparation of shape-controlling V0_(2)(M/R)nanoparticles via one-step hydrothermal synthesis

In this study,we developed a facile one-step hydrothermal process that allows to synthesize high-purity V0_(2)(M/R)nanoparticles with various morphologies such as nanorods,nanogranules,nanoblocks,and nanospheres.W dopants are successfully implanted in V02(M/R)unit cells with high doping efficiency,which allows to regulate the size,morphology,and phase of obtained nanoparticles.The underlying regulation mechanism is presented in detail to reveal how hydrothermal products vary with W doping contents,which provides a synthetic strategy for the preparation of shape-controlling V02(M/R)nanoparticles with high purity to satisfy different specific demands for corresponding applications in the field of thermochromic smart windows.