Synthesis And Electrocatalytic Hydrogen Evolution Reaction Research Of Carbon-based Molybdenum Sulfide Electrocatalyst

Hydrogen energy has been pursued because of its high energy density and no emission of carbon compounds during the oxidation process as a clean energy.The water electrolysis technology is an idea clean technology for large-scale production of hydrogen.However,high energy is needed to overcome the dynamics problems caused by the overpotential.Up to now,the most effective electrocatalyst of water electrolysis is Pt-based metal catalysts.However,Pt is a kind of noble metal with high price and scarce amount.Therefore,molybdenum sulfide?MoS_x?with low cost and high electrocatalytic activity for water electrolysis has gradually attracted people's attention.But MoS_x has the nature of lamellar structure and semiconductor which go against the enhancement of the number of the active sites and the high efficiency of using the active sites.At present,the main methods to improve the electrocatalytic activity are as follows:?1?designing an unique nanostructure of MoS_x to increase the number of catalytic active sites;?2?preparing heterogeneous structure by doping to improve the conductivity and stability;?3?changing the internal structure of the active phase to enhance the intrinsic catalytic activity.In this thesis,we have studied MoS_x and MoS_x compounded with different carbon materials by hydrothermal?solvothermal?method and analyzed the relationshid between the structure and electrocatalytic acticity of MoS_x and carbon-based MoS_x through the detailed physical characterization and electrocatalytic measurement,discussed the mechanism of the enhancement of electrocatalytic hydrogen evolution.?1?We have studied the effect of pH on the morphology,growth mechanism and electrocatalytic activity of hydrogen evolution reaction?HER?of MoS₂,using Na₂MoO₄·2H₂O and CH₃CSNH₂ as the raw materials,which provided reference for the synthesis of MoS₂ with high HER activity.?2?We have investigated the effect of mixed solvents with viarious ratio of DMF and H₂O on the synthesis of MoS₂ and its HER activity,using?NH₄?₂MoS₄ as the precursor.The results show that controlling the ratio of the mixed solution is an efficient method to prepare MoS₂ with high HER acticity.?3?We have synthesized MoS₂/CNs coated with ultrathin MoS₂ sheets,using the carbon nanospheres as the support.We also discussed the effects of solvents,temperature and function groups on the surface of carbon nanospheres on the composite structure of MoS₂/CNs and its HER activity.?4?We used graphene oxide?GO?as support to synthesize MoS_x/GO with high dispersion of MoS_x.We also discussed the effect of GO with different oxidation degree on the morphology,structure and dispersion degree of MoS_x in MoS_x/GO.Combining with the differences of HER activity,the impacts of GO oxidation degree on the HER activity have been analyzed.On the basis of the results,choosing GO with right oxidation degree,we have investigated the effects of different solvents on the composite structure and HER activity of MoS₂/RGO prepared by the solvothermal method.