Modification Of Molybdenum Disulfide By Gold Nanoparticles And Its Catalysis

Hydrogen energy is a clean and important energy source that can gradually replace fossil fuels.At present,a variety of hydrogen production methods,such as hydroelectrolysis and thermal decomposition,have appeared on the market.In hydrolysis,catalyst can be mainly used and overpotential can be reduced,which is easy to form in the reaction process,so the preparation efficiency can be significantly improved.In general,electrochemical water cracking requires a good electrochemical catalyst,which should be cost-effective,stable,environmentally friendly,efficient and have a low overpotential.As the most active and chemically stable electrocatalyst for hydrogen evolution reaction(HER),platinum is the most effective catalyst for hydrogen generation.However,the high cost of PGE restricts their large-scale application.Fortunately,molybdenum disulfide(MoS₂)with a two-dimensional(2D)layered crystal structure is expected as a catalyst for HER due to its low cost and high electrocatalytic performance.Single layer tungsten disulfide(MoS₂)is a typical member of the semiconductor transition metal dihalide family.Two-dimensional transition metal chalcogenides can be obtained by many methods,such as hydrothermal method and electrochemical stripping method.In this paper,the preparation of this kind of material,including the application of chemical vapor deposition method,the growth of large area,high quality MoS₂,through the adjustment of the parameters(growth temperature and time,and argon flow,etc.)a series of studies,and then prepare the target product,determine the best preparation parameters.In order to clarify these parameters,Raman spectroscopy and other analysis were used.Two-dimensional transition metal chalcogenides also have some shortcomin gs,such as atomic vacancies and dislocation,grain boundaries,etc.Since the s tructure of the material itself determines the properties of the material,these d efects affect the properties of the material.The catalytic performance of 2H-MoS₂is severely hindered by the inactivity of the base plane,the few active s ites and the poor conductivity.It is found that the catalytic activity of MoS₂ c an be improved by structural defects,heterojunctions,atomic doping and atomi c modification.To overcome these shortcomings,we increased HER activity of molybdenum disulfide by exposing more edges or attaching molybdenum disulfi de to conductive substrate.The main research contents of this paper are as foll ows:In this paper,the exploration experiment of gold particles under the influence of temperature and deposition time was firstly explored.MoS₂modified with Aunanoparticles was prepared by CVD method under certain conditions,and Au-MoS₂composite film was obtained.For Au-MoS₂,Raman spectrum analysis was applied to clearly characterize its structure and internal electron interaction,which came from Auand MoS₂.Finally,in order to study its catalytic ability,namely HER,electrochemical analysis was applied.The results showed that the electrons of Aunanoparticles moved and successfully reached the conduction band.It is mainly located in MoS₂,which improves its charge density and achieves certain catalytic effect.Moreover,the electrocatalytic hydrogen evolution performance of the prepared composite has been greatly improved:the overpotential,RHE and Tafel slope are 340 mV vs,83.4 mV/Dec,and the overall performance of the obtained material is good,even close to the precious metal Pt.Compared with the current various electrocatalysts,based on MoS₂,the performance of the material is obviously better,can overcome some defects of molybdenum disulfide,such as weak electrical conductivity,and at the same time,it is conducive to improve the active specific surface area,and finally obtain a better product.Gold nanoparticles(AuNPs)have excellent electrical conductivity,high specific surface area and surface properties.AuNPs can not only improve the electronic properties of molybdenum disulfide,but also increase the specific surface area of the composite.Improve the electrocatalytic performance of gold and molybdenum.We have implemented strategies to increase HER activity of molybdenum disulfide by exposing more edges or by attaching molybdenum disulfide to conductive substrates.For example,various metal nanoparticles such as Pt and Pd have been incorporated into molybdenum disulfide nanosheets,effectively increasing the activity of molybdenum disulfide.It is worth noting that,Molybdenum disulfide modified with gold nanoparticles is particularly effective for HER due to the strong Au-S interaction and the excellent stability of gold particles.By chemical vapor deposition growth method,gold nanoparticles were modified on the edge and wire defects of molybdenum disulfide base plane,so that the gold nanoparticles improved the charge transport of molybdenum disulfide and improved HER catalytic efficiency.