MoS₂ And Two-Dimensional Transition Metal Carbides/Nitrides ?MXenes? Van Der Waals Heterostructures:A Theoretical Study

In this thesis,a first-principles method based on density functional theory is used to study the electrocatalytic hydrogen evolution reaction characteristics of two-dimensional molybdenum disulfide?MoS₂?and two-dimensional transition metal carbide/nitride?MXenes?van der Waals heterostructures using a projection-enhanced plane wave PAW,a generalizedgradientapproximationintheformof Perdew-Burke-Ernzerhof and a modified BEEF-vdW function of van der Waals interaction.Two-dimensional MoS₂ and two-dimensional M₂XO₂are assembled,and M=Sc,Ti,V,Cr,Mn,Y,Zr,Nb,Mo,Hf,Ta,and W,X=C or N in M₂XO₂.MoS₂?x?and M₂XO₂?y?are assembled,MoS₂?x?means containing sulfur vacancies MoS₂,and M₂XO₂?y?means containing oxygen vacancies Mo₂CO₂.Various van der Waals heterostructures were constructed to optimize the interaction of heterostructure interfaces to enhance the catalytic activity of MXenes for hydrogen evolution in the van der Waals heterostructures.In recent years,the use of transition metal disulfides as catalysts in electrochemical hydrogen evolution reactions has rapidly increased.The rich chemical composition and a range of MXenes structures make MXenes a number of potential applications.The use of MXenes as electrocatalysts has attracted the attention of scientists.We have demonstrated by first-principles calculation that the assembly of MoS2 and MXenes van der Waals heterojunctions can activate the catalytic activity of the MXenes inert surface.Combining MoS2 with various two-dimensional nanostructured MXenes aims to fine-tune the MXenes hydrogen adsorption free energy and increase the MXenes electrocatalytic activity.The results demonstrate the potential of van der Waals heterojunctions and provide theoretical guidance for the design of transition metal electrocatalyst materials.