Preparation And Electrocatalytic Hydrogen Evolution Of Molybdenum Disulfide Nanowalls On Carbon Paper

The development of modern society has a huge demand for renewable energy and environment-friendly energy.Hydrogen has a high energy density and zero carbon emissions,which is regarded as the most ideal energy carrier in the future.It was found that the Gibbs free energy of hydrogen atoms adsorbed by molybdenum disulfide is close to zero,which can be used as a catalyst to the hydrogen evolution reaction of platinum group noble metals.Chemical Vapor Deposition?CVD?is considered to be the most practical technology for synthesizing large area,high quality,size and thickness controllable MoS₂ with different morphology,including nanotubes,nanowires,nanosheets,etc.,which are related to MoS₂ anisotropic structure.The vertical distribution of MoS₂nanosheets results in a wide range of edge sites due to the high aspect ratio nanostructures,which have great potential in the hydrogen evolution reaction?HER?.Using a self-made CVD system,molybdenum trioxide and sulfur dioxide were combined as precursors to successfully prepare vertically distributed MoS₂nanosheets,namely MoS₂ nanowalls,on carbon paper surfaces.In order to further improve the catalytic activity of the MoS₂ nanowalls,it was subjected to hydrogen treatment and synthesis of a MoS₂/MoO_x heterostructure.Hydrogen-treated the MoS₂ nanowalls prepared on the surface of carbon paper shows the correlation between the number of defects in the specific post-synthesis MoS₂ and the HER performance.The original MoS₂ nanowalls were synthesized by chemical vapor deposition?CVD?and then subjected to hydrogen annealing.This resulted in the formation of sulfur vacancies and increased the number of active sites.The time during which hydrogen is introduced,the temperature of hydrogen annealing,and the hydrogen flow rate all affected the catalytic activity of the MoS₂nanowalls.Through the comparison of the catalytic activities of different gases on the annealing of MoS₂ nanowalls,the effect of hydrogen on the catalytic activity of MoS₂ nanowalls was demonstrated.Prepare molybdenum oxide on the surface of carbon paper using different temperatures,followed by vulcanization to obtain a MoS₂/MoO_x heterostructure.Such a structure has several advantages of improving HER activity.First,the MoS₂nanosheets serve as a protective layer of the underlying molybdenum oxide in the HER acidic electrolyte environment.Second,the MoS₂/MoO_x structure has high specific surface area.Third,the underlying conductive molybdenum oxide allows efficient charge collection and charge transfer to facilitate proton reduction reactions.