Tuning The Mechanical And Electrical Properties Of The Ti₂CO₂ Mxene By Applying Strains

MXenes have attracted intensive attentions,for example,its high specific surface area,good electrical and hydrophilic properties in energy storage,functional enhancement materials,electronic devices,etc.As a well-studied member of the MXene family,Ti2CO2 has been demonstrated to be semiconducting with ultrahigh carrier mobility,acting as a candidate material for electronic devices.As One of the well-studied members of MXenes,Ti₂CO₂,as an earlier prepared and studied MXene,has been achieved by high-temperature treatment of the corresponding hydroxy-functionalized Ti2C?OH?2,which has been shown to have ultra-high carriers.Mobility semiconductors can be used as candidates for electronic devices.Based on the current demand for flexible electronic devices,the mechanical and electrical properties of device materials under strain are critical.In order to further investigate the possible role of Ti2CO2 as a component of flexible electronic devices,the mechanical and electrical properties of Ti2CO2 under strain were investigated,and more useful MXenes structures were discovered,which expanded the number of useful structures.In this work,combined with the first-principles density functional calculations and the Boltzmann transport theory,the influence of monolayer thickness on the electrical conductivity and strain effect of Ti₂CO₂ is first investigated.Then,the relationship between layer thickness and electrical conductivity was also studied for bilayer Ti₂CO₂ materials.Due to the layer-interaction induced band splitting,the band gap of Ti₂CO₂ generally decreases with increasing layers.Based on the generalized gradient approximation?GGA?,the band gap in monolayer Ti2CO2 is determined to be 0.260 eV,which decreases to 0.0369 eV in the five-layer configuration.Further,the strain influence on the electronic structure of the multilayer Ti₂CO₂ is studied.With increasing compression strains perpendicular to the basal plane,the configuration is found to transform from a semiconductor transformed to a semimetal,then to a semiconductor,and last resulted in a metal.This result implies that the electronic property of the multilayer Ti₂CO₂,can be efficiently manipulated by strain and that the multilayer configurations could be applied in strain sensors.In order to further expand this application,we continue to study the stain of the properties of multilayer MXenes materials,including Ti₂CF₂,Ti₂C?OH?₂,Hf₂CO₂ and Zr₂CO₂ materials,to provide a new idea for exploring semiconductor applications.Therefore,our work may open a door to realize bulk semiconductors through compressing of accordion-like multilayer MXenes.