| In today’s world,the consumption of traditional fossil fuel and environmental pollution are pressing issues that need to be urgently solved.It is crucial and practical to achieve energy storage and conversion through photochemistry or electrochemical methods.Two-dimensional（2D）materials are currently a popular research area in energy fields such as water splitting,fuel cells,and metal-air cells due to their exceptional structural and electrical properties.Among them,hydrogen evolution reaction（HER）,oxygen evolution reaction（OER）,oxygen reduction reaction（ORR）and other kinds of reactions play a key role in water splitting,fuel cells,metal-air batteries,reasonable catalyst design has a significant impact on the reaction rate and efficiency.In recent years,single atom catalysts（SACs）have been developed by transforming the active sites of bulk catalysts into isolated atoms,resulting in more efficient catalysis.The SACs have unique advantages such as an unsaturated coordination environment and surface charge redistribution.In renewable energy technologies and other industrial processes,single metal atoms have been anchored in various 2D materials.Recently,as a kind of semiconductor with high stability,enrich sites and wide band gap,Gallium Thiophosphate（GaPS4）has been synthesized experimentally.It is a novel 2D material with 2D layered structure similar to Mo S2.Researches indicate that GaPS4is a promising SAC for energy conversion and storage.Based on the density functional theory（DFT）first-principles calculation method,this thesis investigated the catalytic activity and catalytic reaction mechanism of GaPS4as a photocatalyst by regulating the electronic structure of GaPS4through introducing defects,single atom doping,and strain engineering.The main research contents and results of this paper are as follows:（1）The regulation of single atom doping GaPS4on water splitting performance was studied based on DFT.Results show that the Pt@VS1-GaPS4system has a VBM/CBM band edge position lower（higher）than the oxidation（reduction）potential of O2/H2O（H+/H2）,and a band gap less than 3.0 e V.In addition,it is found that the optical absorption rate of Pt@VS1-GaPS4is better than that of the intrinsic semiconductors GaPS4beyond 290 nm.These findings suggest that the catalytic performance of GaPS4can be significantly improved through transition metal（TM）anchoring,providing important insights for acquiring stable water splitting with GaPS4photocatalysts and theoretical guidance for experimentalists.（2）In the article,to explore the hydrogen evolution activity of two-dimensional GaPS4by DFT and machine learning（ML）.We introduce the S atom vacancy defect in the intrinsic semiconductor,then find that HER activity was not ideal.Inspired by work（1）,we study the HER activity of GaPS4by doping TM into it.It was observed that TM doping significantly enhanced the adsorption of H atom,and the Gibbs free energy change(ΔGH*)value of H atom of Ni@VS1-GaPS4is-0.01 e V.The ML approach revealed that electron affinity（χm）and first ionization energy（Im）are closely related to hydrogen adsorption behavior.Additionally,it was found that strain can significantly improve the catalytic performance of Pt@VS1-GaPS4.In the end,the nudged elastic band method was used to calculate the reaction transition state,which shows that the Heyrovsky process is the rate-determining step on the Pt@VS1-GaPS4electrode.（3）In this paper,the OER and ORR properties of single atom catalyst GaPS4are regulated based on strain engineering.Out of 34 TM doping systems,Pt@VS1-GaPS4was identified as an efficient bifunctional ORR/OER catalyst with an overpotential of 0.59/0.41V.In addition,optimizing the catalytic activity of Pt@VS1-GaPS4by biaxial strain,we found that the overpotential of OER/ORR decreased to 0.37/0.33V at 3%tensile strain.The underlying strain modulation mechanism is attributed to bond angles associated with the TM.These findings provide theoretical guidance for the development of more efficient electrocatalysts through strain engineering. |
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