Controllable Synthesis And Electrocatalytic Performances Of MoS₂ Nanosheet Arrays Cmposites

The electrochemical hydrogen production and reduction of carbon dioxide has been recognized to be an efficient way to solve the energy crisis and alleviate climatic issue.Current hydrogen evolution reaction?HER?and CO₂ reduction reaction?RR?catasysts are still facing with some problems such as less active sites,poor conductivity,and high over-potential.Among many electrocatalysts reported,low-cost molybdenum disulfide have attracted much attention due to their unique electronic structure and the associated electrochemical properties.In particular,it is still a scientific problem to realize the electrocatalytic reduction of CO₂ over MoS₂ in aqueous solution.Considering the above facts,in this dissertationt,MoS₂ nanosheet arrays were synthesized and their HER activity was enhanced through modification of noble metal nanoparticles.On the other hand,the selectivity of electrocatalytic CO₂RR of MoS₂ was improved through combining with inert HER catalysts.The main points are as follows:?1?MoS₂ nanosheet arrays were synthesized through a facile hydrothermal route,using thiacetamide,ammonium,and ammonia molybdate as raw materials.MoS₂ nanosheet arrays were grown on Mo mesh wires substrate.Using the reductive ability of the synthesized MoS₂ nanosheets themselves,without use of additional reducing agent,different noble metals were loaded on MoS₂ nanosheet arrays by the redox reaction between MoS₂ and correponding noble salt at room temperature.Electrochemical properties of noble metals/MoS₂ composite materials were studied.Taking Pd/MoS₂ as an example,the influence of the size and content of noble metals nanoparticles on its electrochemical performance wassystematically investigated.The method on fabricating precious metal nanoparticles/MoS₂ composite through by redox reaction between MoS₂ nanosheets and noble metal salts provides a new strategy for designing highly efficient electrocatalysts.?2?The MoS₂ nanosheet array electrode was prepared by a facile solvothermal method.PbMoO₄/MoS₂ composite material was prepared by a simple solvothermal method,using MoS₂ nanosheet array electrode as the substrate.It was found that HER of MoS₂ was efficiently inhibited in the presence of PbMoO₄ and the overpotential of corresponding electrocatalytic CO₂ RR over Pb was significatnly reduced.Compared with PbMoO₄ and PbMoO₄/MoS₂ core-shell structure the as-synthesized PbMoO₄ nanoparticles located at MoS₂ nanosheet edges composites are more favorable to the electroreduction of CO₂.This work provides a useful reference for the design of new and efficient electrocatalysts for selective carbon dioxide reduction in an aqueous system.