First-principles Study On The Gas Sensing Properties Of Antimonene By Metal Doping And Defects

In recent years,gas sensing technology has penetrated into every link of industrial production and daily life,and played an irreplaceable role in toxic gas detection.As the core component of gas sensor,high performance gas sensing materials can quickly detect and capture toxic gas molecules.Therefore,the design of gas sensing materials with high stability,high selectivity and high sensitivity has become a research hotspot in the field of gas sensing.Two-dimensional（2D）nanomaterials show great potential in the field of gas sensing due to their special structure and excellent properties,and their layered structures and high electrical conductivity provide more possibilities for gas sensing.In the process of VA 2D materials research,antimonene monolayer shows good stability,excellent electronic properties and excellent optical properties.Theoretical and experimental studies suggest that antimonene monolayer exhibits great application potential in the fields of optoelectronics,catalysis,energy and biomedicine.It is worth noting that the large surface-to-volume ratio,adjustable band gap and high carrier mobility make antimonene monolayer have natural advantages in the field of gas sensing.However,the research on the gas sensing properties of antimonene is still in the initial stage,and the research of gas sensor based on antimonene monolayer is still progressing slowly.Therefore,this paper systematically studied the adsorption behavior and sensing properties of antimonene monolayer for toxic gas molecules using the first-principles calculations.By revealing the gas sensing mechanism,it provides a reliable theoretical basis for the detection of toxic gas by antimonene gas sensor.The research contents and results are as follows:（1）The adsorption behavior and sensing properties of CO,SO₂and NO₂molecules on the intrinsic and transition metal（Ni,Pd and Pt）doped antimonene monolayers are studied to reveal the applicability of Ni,Pd and Pt doped antimonene monolayers as highly selective and sensitive gas sensing materials.The results show that the adsorption ability of intrinsic antimonene monolayer for CO,SO₂and NO₂is weak,which is unfavorable to sense and capture of toxic gases.Based on the analysis of adsorption energies,charge transfers and density of states,it can be seen that Ni,Pd and Pt doping can improve the adsorption ability of antimonene monolayer to CO,SO₂and NO₂and enhance the interaction between substrate and gas.The electron local function（ELF）analysis can determine the covalent interaction between gas molecules and transition metal doped substrates.The conductivity,recovery time and work function show that the Ni,Pd and Pt doped antimonene monolayers are more selective and sensitive to NO₂molecule than CO and SO₂molecules.In addition,Ni doping can significantly enhance the interaction between antimonene substrates and NO₂,which has better sensing and capturing properties for NO₂molecules.The adsorption behavior and sensing properties of NO₂on Ni doped antimonene substrate can be adjusted by applying electric field,indicating that external electric field is a controllable method of NO₂capture and release.The purpose of this work is to provide a theoretical basis for the application of gas sensors based on antimonene.The transition metal doped antimonene monolayers can be used as candidate materials for the sensing and capturing of CO,SO₂and NO₂gases.（2）In order to explore the effect of metal doping and vacancy defects on the gas sensing properties of antimonene,the models of transition metal（Sc and Ti）doped intrinsic antimonene and defected antimonene monolayers are constructed,and the effect of single vacancy defect and transition metal doping for the substrate properties are discussed.single vacancy defect antimonene and Sc doped defected antimonene show metallic properties,Sc doped antimonene and Ti doped defected antimonene show semiconductor properties,and Ti doped antimonene shows magnetic semi-metallic properties.The modified substrates have certain differences in electrical and magnetic properties,which also provides more possibilities for the adsorption and sensing of NO gas.The calculation results of adsorption energies,charge transfers,density of states and charge density difference show that the adsorption ability of the intrinsic antimonene monolayer to NO is weak.The introduction of single vacancy defect and transition metal atom doping can enhance the adsorption ability of antimonene monolayer to NO.The strong orbital hybridization between NO and the modified substrates is the main reason for the improvement of adsorption ability.The analysis of ELF shows that there is weak van der Waals interaction between the intrinsic antimonene monolayer and NO.There is strong covalent interaction between the single vacancy defected substrate and NO,and the covalent bond is formed in the NO adsorption process.There is electrostatic interaction between transition metal doped intrinsic substrate and defected substrate and NO,and ionic bond is formed in the adsorption process.The work function analysis results show that the introduction of single vacancy defect and transition metal doping is beneficial to improve the sensing properties of antimonene substrate for NO.Sc doped intrinsic antimonene and defected antimonene substrates show significant sensitivity to NO.Compared with O₂,H₂O and CO molecules,Sc doped intrinsic antimonene and defected antimonene substrate also has stronger selectivity for NO molecule.In addition,the optical absorption coefficients of all adsorption systems are greater than the isolated substrates in the visible region of 380 to 790 nm,indicating that optical gas sensors based on antimonene can be used for the detection of toxic NO molecule.