In-situ Raman Spectroscopic Study On The Structural Evolution Of Molybdenum Disulfide-based Catalysts During Hydrogen Evolution

As a non-precious metal electrocatalytic hydrogen evolution catalyst,molybdenum disulfide（MoS₂）has attracted people’s attention because of its abundant resources and low price.In recent years,many studies on the regulation of MoS₂electrocatalytic hydrogen evolution performance have done,but few studies focused on the effects of structural evolution on the enhanced HER for noble metal nanoparticles（NPs）@2H-MoS₂.In this work,the effects of structural evolution on the enhanced HER for noble metal（Pd,Au,Ag）NPs@MoS₂were investigated by a modified in-Situ electrochemical Raman spectroscopy.The major results can be summarized as follows:（1）Development of an in-situ electrochemical Raman spectroscopy deviceA modified electrochemical cell was designed to drive the bubbles formed during a gas evolving reaction away effectively.The Raman spectroscopy,electrochemical workstation and the modified electrochemical cell are combined together to an in-Situ electrochemical Raman spectroscopy system to investigate the electrocatalysts’structural evolution during the HER.（2）Design,synthesis and in-situ Raman spectroscopy study of Pd-MoS₂ catalystPd NPs decorated MoS₂（Pd-MoS₂）show higher HER performance than MoS₂.The electrocatalysts’structural evolution results show that the terminal S-S is the true active sites and Pd NPs decoration can promote the appearance of terminal S-S bonds earlier.In addition,Pd NPs decoration could make some bands shift dramatically,making or breaking some chemical bonds of MoS₂,which probably relate to the enhanced HER.（3）Design,synthesis and in-situ Raman spectroscopy study of Ag-MoS₂,Au-MoS₂catalystsAu and Ag NPs decorated MoS₂（Au-MoS₂,Ag-MoS₂）show higher HER performance than MoS₂,and Au-MoS₂ is better.Ag,Au NPs decoration will promote the A_1g（M）-LA（M）,LA（M）shifts and produce new peaks including E_1g,A_1g（M）and A_2u,which may promote the HER performance enhancement.In addition,Au NPs decoration can promote these structure changes earlier,which may relate to the higher HER performance of Au-MoS₂.