Research On The Fabrication And Electrochemical Catalytic Performance Of Individual MoS₂ Nanosheet Based Hydrogen Evolution Reaction Device

Because of the non-renewable nature of fossil fuels and the environmental pollution caused by its burning,the demand of new clean energy is growing.Hydrogen energy as an important part of the future renewable energy draws more and more attention.However,hydrogen gas as the hydrogen energy carrier is very less in the air,which greatly limits the development and utilization of hydrogen energy.In view of this,the production of hydrogen needs a high-efficient and economical way to meet the increasing demand.The water splitting,as a well-known way for H₂production,has attracted more and more attention for the advantages of non-pollution and abundant sources.In order to reduce the consumption of electricity,the water splitting reaction needs catalysts to reduce the electrochemical overpotential.At present,the best catalysts are Pt-groups metals,while its practical application is limited by the rare reserve on the earth.Therefore,an economical and efficient catalyst is the key to the large-scale development of hydrogen energy.Recent research has proven that MoS₂ is a promising candidate of the catalyst to take place of the precious noble metal.But the few number of active sites and poor conductivity of MoS₂ plane limit the further utilization.In order to solve the drawbacks,a series of means,most focusing on the crystal structure and morphology of MoS₂,have been reported to enhance the catalytic performance of MoS₂.In this paper,we have successfully fabricated a field-tuned individual MoS₂nanosheet based HER device.The electron transport speed in the catalytic reaction can be enhanced by the field effect from the applied electric field,then the catalytic performance of MoS₂ nanosheet will be improved.The main conclusions are as follows:?1?The successful fabrication of field-tuned individual MoS₂ nanosheet based HER device.And the three-electrodes plus back-gate test system for the individual MoS₂ nanosheet based HER device was designed by combining the electrochemical test system and the field-effect transistor test system.The unique test system was used to investigate the influence of field effect on the catalytic performance of MoS₂.?2?From the experiment results,it can be found that the field effect can significantly enhance the HER performance of MoS₂.With the gate voltages increasing from 0 to 5 V,the onset overpotential(100 mA cm^-2)of MoS₂ nanosheet has decreased from 240 to 38 mV,and at the same time,the Tafel slope has decreased from 200 to 110 mV dec^-1.The best catalytic performance of MoS₂ nanosheet can be comparable with that of Pt in the same system.?3?From the I-V curves of the individual MoS₂ nanosheet based HER device at different gate voltages,it is found that the channel conductance of individual MoS₂nanosheet based HER device keeps raising from 0.055 to 0.1776 S m^-1,the channel conductance is improved more than three times,when increasing the gate voltage from 0 to 5 V.?4?The enhanced catalystic perfoemance of MoS₂ nanosheet is contributed from the field effect injected electron which can modify the band structure of n-type MoS₂and improve the charge transport in the channal.