Study On Defect Induced Oxidation Behavior And Hydrogen Evolution Application Of MoS₂ Nanosheets

The world energy system is undergoing the third energy transformation with the direction of low pollution,low carbon and recyclability,and hydrogen energy as a green,low-carbon,safe and sustainable secondary energy is the most important role in this energy transformation.One of the effective ways to obtain hydrogen energy is to design a unique catalyst to build an efficient and stable water desorption hydrogen system.The key of this technology is the development and utilization of the catalyst.Molybdenum disulfide（MoS₂）is the best catalyst for hydrogen evolution reaction because of its excellent catalytic activity and unique electronic structure.However,the improvement of MoS₂ catalytic efficiency is greatly limited by the inert base surface.Therefore,in order to further improve the hydrogen evolution efficiency of MoS₂,researchers have adopted a variety of adjustment strategies to activate the inert base of MoS₂.Among them,oxidation engineering is one of the effective strategies to improve the performance of catalytic hydrogen evolution reaction by optimizing the chemical properties of MoS₂.This paper is based on the research of MoS₂ oxidation process,focusing on the changes of the morphology and electronic structure of MoS₂ during the oxidation process;explore the relationship between oxidation degree and hydrogen evolution efficiency;guided by theoretical calculation and based on the MoS₂ oxidation structure model,it provides theoretical guidance and technical support for the design of efficient MoS₂ based hydrogen evolution reaction catalyst.The main research contents of this paper are follows:1.The spontaneous oxidation behavior of MoS₂ is driven by surface defects,and the oxidation degree of MoS₂ is controlled by oxidation time.At different oxidation stages of MoS₂,its morphology,structure,elemental composition and valence were characterized by SEM,TEM,HRTEM,Raman and XPS.The changes of oxidation degree and photothermal properties were analyzed by UV/visible near-infrared spectroscopy and thermal imaging instrument.2.The catalytic hydrogen production performance of oxide-MoS₂/Triethanolamine/Eosin dye sensitized system was evaluated by using the online monitoring system of photocatalytic hydrogen production.The experimental results of dye sensitized catalytic hydrogen evolution show that the maximum hydrogen evolution rate of oxide-MoS₂ can reach 7.85 mmol h^-1 g^-1 under EY sensitization,which is much higher than that of non-oxidized MoS₂.The results showed that the photocatalytic hydrogen evolution performance of the corresponding system could be significantly enhanced by using oxide-MoS₂ as（co）catalyst.3.The atomic structure model of oxide-MoS₂ is constructed and optimized.The electronic structure,Gibbs free energy of hydrogen adsorption and energy band structure of oxide-MoS₂ are analyzed based on the first principle.It is further confirmed theoretically that oxide-MoS₂ nano-sheet has excellent photocatalytic activity.