Preparation And Study Of Heteroatom-Doped Tungsten-based Electrocatalyst For Hydrogen Evolution Reaction

Hydrogen with high energy density,rich resources and clean is a promising green energy carrier.Water electrocatalysis is the most simple and effective way to prepare high purity hydrogen and oxygen.The water electrolysis is divided into hydrogen evolution reaction?HER?at cathode and oxygen evolution reaction?OER?at anode.Platinum based catalysts are the most efficient electrode materials for the electrolysis reaction,but the large-scale application of platinum is restricted because of the high price and limited reserves.Therefore,the development of high-performance non-noble metal catalysts for hydrogen production is more important to solve the above problems.Transition metal based catalysts have attracted more attention due to their abundant natural resourse and low prices.Among them,tungsten?W?and its compounds have attracted much attention due to their excellent stability,however,the intrinsic catalytic performance of W-based catalysts is relatively low.In this paper,cobalt doping is proposed to improve the performance of W-based catalysts.The main research contents are as follows:?1?WO₃ nanowires doped with Group VIII metals?Fe,Co,Ni?were prepared on carbon cloth by hydrothermal method,and then the doped WN nanowire arrays were obtained by nitriding.Co doped WN nanoarrays?Co/WN NWs?exhibits porous structure,and Co dopants is evenly distributed in nanowires.Co/WN NWs shows outstanding performance in wide pH range,such as 151 mV??10?and tafel slope of 82 mV dec^-1 in alkaline solution,209 mV and tafel slope of 92 mV dec^-1 in acidic solution,as well as the excellent stability after 20 h testing with 99%retention of applied voltage.Density functional theory?DFT?and density of states?DOS?calculations confirm that Co doping can effectively reduce the d-band center of the W site,which is due to the electron transfer from W to Co,thus reducing the adsorption energy of H on Co/WN.Therefore,the properties of WN were mainly attributed to the regulation of the d-band center of W and the introduction of Co site.?2?The tungsten oxide nanowire array and cobalt-doped tungsten oxide nanowire array grown on the carbon cloth were prepared by hydrothermal method,and then the tungsten phosphide?WP₂?nanowire array and co-doped tungsten phosphide?Co/WP₂?nanowire array were obtained after phosphorizatione.The results show that Co is uniformly distributed in the WP₂ nanowire arrays and significantly improves the HER performance in a wide p H range solutions,such as a small overpotential of 79 mV(?₁₀)with Tafel slope of 52 mV dec^-1 in an alkaline solution and 99 mV with a Tafel slope of62 mV dec^-1 in an acidic medium in addition to the excellent durability with 92%voltage retention after 20 h.The excellent electrocatalytic performance can be attribute to the increasing electron density around P atom,thereby enhancing the HER performance of WP₂.