Gas Sensing Performance of Pristine and Monovacant C6BN Monolayers Evaluated by Density Functional Theory and the Nonequilibrium Green's Function Formalism

The application potential of pristine and monovacant C6BN for sensing gaseous pollutants (CO, CO2, NO, NO2, NH3, H2S, and SO2) is investigated using density functional theory with van der Waals dispersion correction. The adsorption sites and distances are determined. In addition to applying widely used theoretical approaches (adsorption energy, charge transfer, and work function) to evaluate gas sensing properties, the current-voltage characteristics are calculated before and after gas adsorption, using the nonequilibrium Green's function formalism. The reliability of the approaches is analyzed. From a material point of view, we observe that all molecules under investigation physisorb on pristine C6BN. However, it turns out that pristine C6BN cannot be used for sensitive sensing, which we attribute to tiny charge transfers and band gap changes. On the other hand, we find that monovacancies in C6BN improve the adsorption energy and, in turn, enhance the sensitivity.