Sensing properties of NO2 gas sensor based on nonmetal doped α-AsP monolayer: A first-principles study

α-AsP monolayer is a two-dimensional (2D) black phosphorene-like material with potential applications in electronics and gas sensors due to ultra-high carrier mobility. Here, we investigate the gas sensing properties of nonmetal (Si and S) atoms doped α-AsP monolayer using the first-principles calculations based on the density functional theory (DFT-D2 method). The results show that the nonmetal doping can significantly improve selectivity and sensitivity toward NO2 compared with other interfering gas molecules. Especially, the S doped α-AsP monolayer possesses a high selectivity to NO2 with moderate adsorption energy of −0.82 eV, a high sensitivity with significant WF change of 0.39 eV and larger sensitivity value of 53.8 %. By analyzing the electron localization function (ELF) and electronic structure, the enhanced adsorption ability of the S doped α-AsP monolayer to NO2 is mainly determined by electrostatic interaction. In addition, adsorption behavior of NO2 on S doped α-AsP monolayer can be effectively affected by applying external strain and electric field, meaning that strain/electric field can be used as a controllable method for gas storage and release. Therefore, these results not only provide fundamental insights for nonmetal doped α-AsP monolayer as promising gas sensing material for NO2 detection, but also provide a theoretical guideline for designing high performance gas sensors based on 2D AsP.