2D Bi2O2Se Based Highly Selective and Sensitive Toxic Non-Condensable Gas Sensor

this study, we discussed the interaction of toxic NCG with monolayer (ML) Bismuth Oxyselenide (Bi2O2Se) for the first time. The density functional theory (DFT) combined with non equilibrium Green's function (NEGF) were used to investigate gas sensing properties of ML Bi2O2Se with and without Se vacancy. The authors discussed adsorption energy, adsorption sites, charge exchange, band structure, density of states (DOS), and current-voltage properties with adsorbed toxic Non-condensable gases (NO2, NO, NH3, CO, and CO2). Our study indicates that NO2 has the lowest adsorption energy and highest charge transfer that results in superior NO2 selectivity of vacancy less (VL) Bi2O2Se. The band structure and DOS analysis show that adsorption of only NO2 and NO results in the addition of impurity states near the Fermi level in VL Bi2O2Se. The presence of Se vacancy (SV) can further improve the sensitivity and selectivity of Bi2O2Se towards sensing toxic gases when compared with VL Bi2O2Se. It was found that SV Bi2O2Se is most selective towards NO gas with an adsorption energy of-1.59 eV. The ML Bi2O2Se device shows a distinct I-V response upon the adsorption of different gases. Both VL and SV Bi2O2Se devices are most sensitive towards NO adsorption due to their superior response. A high response (S) of 0.99 with a current of 1.11 mu A was achieved from the SV Bi2O2Se device at 0.75 V after NO adsorption. Our theoretical studies indicate that Bi2O2Se can function as a promising gas sensing material.