Two-Dimensional Bismuthene Nanosheets for Selective Detection of Toxic Gases

An in-depth understanding of the practical sensing mechanism of two-dimensional (2D) materials is critically important for the design of efficient nanosensors toward environmentally toxic gases. Here, we have performed van der Waals-corrected density functional theory (DFT) simulations along with nonequilibrium Green’s function (NEGF) to investigate the structural, electronic, transport, thermodynamic, and gas-sensing properties of pristine and defect-crafted bismuthene (bBi) sheets toward sulfur- (H2S, SO2) and nitrogen-rich (NH3, NO2) toxic gases. It is revealed that the electrical conductivities of pristine and defective bBi sheets are altered upon the adsorption of incident gases, which have been verified through transport calculation coupled with the work function and electronic density of states. Our calculations disclose that bBi sheets show superior and selective gas-sensing performance toward NO2 molecules among the studied gases due to a significant charge redistribution and more potent adsorption energies. We find that the mono- and divacancy-induced bBi sheets have enhanced sensitivity because the adsorption behavior is driven by a considerable change in the electrostatic potential difference between the sheets and the gas molecules. We further performed statistical thermodynamic analysis to quantify the gas adsorption abilities at the practical temperature and pressures for the studied gas samples. This work divulges the higher sensitivity and selectivity of bBi sheets toward hazard toxins such as NO2 under practical sensing conditions of temperature and pressure.