Synthesis And Electrocatalytic Performance In Hydrogen Evolution Of Tungsten-based Catalysts

The rapid development of human society has brought about issues of energy shortage and environmental pollution.In order to achieve sustainable development in the future,it is necessary to develop energy sources with high combustion value,cleanliness,and non-polluting characteristics to replace traditional fossil fuels.Hydrogen energy is a clean and sustainable energy carrier with high energy density and the potential to replace traditional fossil fuels.However,the current industrial production of hydrogen mainly relies on steam reforming of natural gas,which has limited output and causes environmental pollution.Hydrogen production through water electrolysis（HER）has received attention due to its simple equipment,mature technology,and high purity of hydrogen gas.However,the reaction kinetics of HER are relatively slow,and designing efficient and stable electrocatalysts is still a challenge.Noble metal materials such as platinum are considered to be the best performing HER electrocatalysts,but high cost,scarcity and long-term stability have prevented their widespread application.Developing efficient non-precious metal-based electrocatalysts for hydrogen evolution is currently one of the research hotspots.Transition metal tungsten-based materials have great potential in catalyzing HER due to their low cost and abundant electronic states.This article discusses the preparation methods,phase composition,morphology,structure,and applications of tungsten-based compounds in catalyzing HER,aiming to obtain efficient and stable electrocatalysts for hydrogen evolution and promote the development and popularization of renewable energy.1.Optimization of hydrogen adsorption on W₂C by late transition metal doping for efficient hydrogen evolution catalysis.A late transition metal M（M=Fe,Co,Ni）doped WO₃ precursor（M-WO₃）was synthesized on carbon cloth（CC）using a hydrothermal method,followed by carbonization at high temperature using melamine as carbon source to obtain M-doped W₂C nanorod arrays（M-W₂C）,while the effects of M doping amount and carbonization temperature on the hydrogen evolution performance were explored.Among them,Ni-W₂C exhibited excellent HER catalytic activity in alkaline electrolytes,with an overpotential of 88 m V at a current density of 10 m A cm^-2 and a Tafel slope of only 73.8m V dec^-1.The experimental results reveal that the excellent activity of the material is mainly attributed to the transition metal doping which effectively reduces the charge transfer resistance,accelerates the charge transfer rate and increases the number of active sites.The subsequent theoretical calculations demonstrate that with the late transition metal doping,the electron cloud density changes and the d-band center of W₂C gradually moves away from the Fermi energy level,resulting in weaker hydrogen adsorption and lower interfacial transfer resistance,thus accelerating the hydrogen evolution reaction process.2.Synergisyic coupling of Ni nanoparticles with W₂C nanowires for highly efficient alkaline hydrogen production.Firstly,the closely distributed WO₃ nanowire arrays were grown on carbon cloth substrate by hydrothermal method,followed by a simple carbonization treatment at800°C under Ar atmosphere using melamine as carbon source to induce the phase transition from WO₃ to W₂C,and finally the heterogeneous structure W₂C-Ni was obtained by depositing metal Ni nanoparticles on W₂C nanowires utilizing electrochemical deposition method.Additionally,the effects of the amount of Ni deposited and the carbonization temperature on the hydrogen evolution performance were also explored.The W₂C-Ni catalysts exhibit excellent HER catalytic activity and are well stabilized.The overpotentials required to drive current densities of 10 and 100m A cm^-2 under alkaline conditions are 37 and 227 m V,which have catalytic activity comparable to that of commercial Pt/C.The experimental results indicate that the formation of heterostructures induces electron transfer from Ni to W₂C,resulting in a strong synergistic coupling effect,which leads to a lower charge transfer resistance and faster electron transport in the HER process.Theoretical calculations reveal that the introduction of Ni nanoparticles can significantly accelerate the dissociation of adsorbed water and promote the Volmer step,while modulating the position of the W₂C d-band center,weakening the adsorption capacity for hydrogen and promoting hydrogen desorption.3.Construction of W_4.6N₄-Co₄N heterostructure for excellent alkaline hydrogen production.The catalysts were synthesized by three simple steps.In the first step,WO₃nanowires were synthesized using carbon cloth as the substrate,and in the second step,Co（OH）₂ layers were deposited on the WO₃ surface by means of electrodeposition,and finally,the W_4.6N₄-Co₄N heterostructures were obtained by annealing at 600°C under NH₃ atmosphere.The effect of electrodeposition time and temperature on the catalyst performance was also investigated in this work.The experimental results show that the HER catalytic activity of the W_4.6N₄-Co₄N heterostructure is significantly enhanced in alkaline electrolytes.In terms of morphology,the combination of nanowires and nanosheets constituted a three-dimensional structure,increasing the specific surface area of W_4.6N₄-Co₄N and exposing more active sites.As for the electronic structure,the combination of W_4.6N₄ and Co₄N effectively regulates the electron redistribution at their interfaces.The optimized W_4.6N₄-Co₄N heterostructure exhibited a fast HER kinetics with an overpotential of 109 m V at a current density of 10 m A cm^-2.