Preparation,Characterization Of The Molybdenum Sulfide Electrode As Efficient Catalysts For Hydrogen Evolution

Wth the fossil energy depletion and environmental problems become serious,hydrogen has been regarded as an ideal efficient,safe and clean green energy source.This is because it is non-toxic,pollution-free,high combustion energy and the product can be recycled.Electrochemical water splitting is a promising and clean way to produce hydrogen,however,it still suffers from the problem of great power consumption in industrialization.In order to save energy,water spliting by using solar energy is an ideal way to produce hydrogen.Therefore,it is theoretical and practical significance to develop high activity hydrogen evolution electrode.In this work,we carried out the research on studying the activity of hydrogen evolution over molybdenum sulfide.The electrodes were characterized by SEM,XPS,TEM and so on,and their hydrogen evolution performances were also investigated.The work is as follows:(1)Molybdenum sulphide nanosheets were synthesized by hydrothermal treatment of Mo mesh in aqueous thiourea solution.Their compositional,morphological and structural properties as well as electrocatalytic activities were investigated in details.The results reveal that molybdenum sulphide nanosheets grown on Mo mesh exhibit an enhanced HER activity with a low onset overpotential of 120 mV and a Tafel slope of 46 mV/dec,which is superior to that of molybdenum sulphide nanosheets grown on Mo foil.(2)Silicon nanowire arrays were prepared by metal-assisted chemical etching of p-type silicon wafer,and their surface were modified with molybdenum sulfur clusters.The results show that,compared with planar silicon,silicon nanowires array show better light absorption and hydrophilicity,and they provide more activity sites for photoelectrochemical reaction.After modified with Mo3S13 cluster,silicon photocathode exhibits an enhanced photoelectrochemical performance for hydrogen production.Under the irradiation of a simulated sunlight(?>590 nm),the silicon nanowire photoelectrode onset voltage is 0.3 V(vs.RHE)and the limiting current reaches up to 15 mA/cm2.The novelties and innovations of this study are as follows:(1)Construct three-dimensional molybdenum sulfide catalysts by using the mesh structure,and this structure could be beneficial to promote the electrolyte diffusion into the electrode surface and thus promote the electron transfer,leading to an enhanced HER performance.Molybdenum mesh as substrate can be directly connected to the circuit as a binder-free electrode.(2)The nanowires array can enhance the light adsorption and hydrophilicity.Compare to the planar structure,nanowires exhibit high surface area and surface defects,which facilitates the adsorption and dispersion on the surface of the nanowires.As expected,the modified nanowires array photocathode showed an excellent hydrogen evolution activity.