2D Bi$_{2}$$O_{2}$Se Based Highly Selective and Sensitive Toxic Non-Condensable Gas Sensor

In this study, we discussed the interaction of toxic NCG with monolayer (ML) Bismuth Oxyselenide (Bi
$_{2}$
$O_{2}$
Se) 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 Bi
$_{2}$
$O_{2}$
Se 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 (NO
$_{2}$
, NO, NH
$_{3}$
, CO, and CO
$_{2}$
). Our study indicates that NO
$_{2}$
has the lowest adsorption energy and highest charge transfer that results in superior NO
$_{2}$
selectivity of vacancy less (VL) Bi
$_{2}$
$O_{2}$
Se. The band structure and DOS analysis show that adsorption of only NO
$_{2}$
and NO results in the addition of impurity states near the Fermi level in VL Bi
$_{2}$
$O_{2}$
Se. The presence of Se vacancy (SV) can further improve the sensitivity and selectivity of Bi
$_{2}$
$O_{2}$
Se towards sensing toxic gases when compared with VL Bi
$_{2}$
$O_{2}$
Se. It was found that SV Bi
$_{2}$
$O_{2}$
Se is most selective towards NO gas with an adsorption energy of -1.59 eV. The ML Bi
$_{2}$
$O_{2}$
Se device shows a distinct I-V response upon the adsorption of different gases. Both VL and SV Bi
$_{2}$
$O_{2}$
Se 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 Bi
$_{2}$
$O_{2}$
Se device at 0.75 V after NO adsorption. Our theoretical studies indicate that Bi
$_{2}$
$O_{2}$
Se can function as a promising gas sensing material.