Interaction study of CO and NO pollutant gases with pristine, defected and doped α-CX (X=N, P) monolayers using density functional theory

CO and NO are two of the most pollutant gases that exist in the environment, which makes their tracing highly crucial. In this problem, we have investigated the adsorption performances of highly toxic CO and NO gases over pristine, defect-tuned, and Al-doped α-CX (X = N, P) monolayers. In addition to the adsorption properties, we have calculated electronic properties such as band structure, projected density of states (PDOS) and charge transfer, sensing properties such as work function and recovery time for pristine, defect-tuned, and Al-doped α-CX before and after the gas adsorption process. Given the poor adsorption energies and large adsorption distances, pristine α-CX monolayers are not suitable candidates for the toxic gas sensors. In case of functionalized α-CX, the adsorption energy is highest in case of C-defected α-CN for CO gas adsorption. For interaction of NO gas molecule with functionalized α-CX, Al-doped α-CN is deemed to be best candidate for adsorption, given the formation of covalent bond. The computed recovery times are extremely long (exceeding several hours) in the best-case scenarios, this implies that C-defected α-CN and Al-doped α-CN are most suitable for CO and NO gas removal applications. Prospectively, one can calculate more electronic device parameters of α-CX monolayers to examine their validity as gas sensor.