Preparation Of Fe Doped Monolayer Tungsten Disulfide And Its Electrocatalytic Performance For Hydrogen Evolution

As an important part of new energy,hydrogen energy is highly expected.However,the content of hydrogen in the natural environment is very low and difficult to be collected,leading to undercutting of its practical applications.After years of development,hydrogen production through water electrolysis has become a mature method for hydrogen production.However,the commercial catalysts for water electrolysis are mainly noble metals such as platinum,which have limited earth reserves and high costs,limiting large-scale industrial application and development.Therefore,finding new high-performance catalysts with abundant reserves and low cost has become the key to the industrial application of hydrogen production by electrolysis of water.Research in recent years has shown that two-dimensional chalcogenide is a promising low-cost catalyst with good catalytic performance and is expected to replace platinum and other noble metal catalysts in the future.However,the intrinsic two-dimensional chalcogenide compound has strong inertness and few active sites,and its catalytic performance is still not comparable to that of noble metals such as platinum.Therefore,the current research on the catalytic hydrogen evolution of two-dimensional chalcogenides is mainly devoted to further improving the catalytic performance,solving the inertness in the plane,and increasing the active sites in the plane.The main methods include heteroatom doping,grain boundary ratio control,and heterojunctions building.In this paper,Fe doped WS₂monolayer two-dimensional crystals were synthesized by chemical vapor deposition method,and through the optimization of the growth parameters,high-quality Fe doped WS₂monolayer crystals with clean surface of tens of microns were successfully prepared.The electrical transport properties and electrocatalytic hydrogen evolution performances of the samples were studied.The main contents are as follows:（1）Based on the mature preparation of pristine WS₂monolayer crystal,Fe₂O₃well matching the preparation conditions of WS₂,was selected as the Fe doping source through many experiments,and Fe atoms were successfully introduced into the lattice of WS₂monolayer two-dimensional crystal.The doped samples were characterized by Raman,photoluminescence（PL）,X-ray photoelectron spectroscopy（XPS）,atomic force microscopy（AFM）and scanning transmission electron microscopy（STEM）.It was observed that the PL peak intensity of WS₂was significantly decreased by the Fe doping.STEM characterization shows that the doping concentration of Fe is between 5%and 10%.The doping of Fe is mainly in the form of triatomic clusters.（2）Field effect transistors（FET）based on pristine and Fe doped WS₂monolayer crystals were fabricated and characterized.In addition,monolithic micro devices for electrocatalytic hydrogen evolution based on pristine and Fe doped WS₂monolayer crystals were fabricated.The corresponding electrochemical tests show that Fe doping greatly improves the catalytic activity of WS₂monolayer crystals.The overpotential and Tafel slope of the Fe doped WS₂are 198 mV at the current density of 10 mA cm^-2and81 mV dec^-1,respectively,which were much better than those of the pristine WS₂.