Phosphorene defects for high-quality detection of nitric oxide and carbon monoxide: A periodic density functional study

The electronic and sensing properties of pristine and defect-tuned black phosphorus monolayer for the monitoring of nitric oxide (NO) and carbon monoxide (CO) at two defect concentrations (0.0165 and 0.0073 angstrom(-2)) were investigated within the framework of periodic density functional theory (DFT). Several configurations with preserved integrity were found plausible for both molecules at the vacant sites in which the ones with the lowest energy favored top site adsorption. We found that the detection sensitivities of all phosphorene layers correlated well with the electrophilicity of the structures. The performance data showed that the defect-free phosphorene layer could not operate as a reliable conductance-based sensor, but could be considered a satisfactory work function sensor for the analytes at hand. On the contrary, the defect-tuned phosphorene layer would be an excellent detector for both molecules, especially providing a high sensitivity at both concentrations (up to 270.0) and excellent reusability (3.6 ms) for the NO detection without any dependence on external manipulation. Carbon monoxide was better detected (1043.3) at a lower concentration, however. Excellent selectivity was observed for both molecules in dry and humid air atmospheres. The corresponding band structures and density of states were discussed. The analysis of the localized orbital locator (LOL) contour maps indicated that the C-P and N-P bonds behaved van der Waals (vdW) and polar covalent types, respectively. Overall, this paper provides attractive data for the rational design of novel chemosensors for the noxious NO and CO molecules.