Adsorption mechanism of Ni decorated α-CN monolayer towards CO, NO, and NH₃ gases: Insights from DFT and semi-classical studies

Toxic gases such as carbon monoxide (CO), nitric oxide (NO) and ammonia (NH₃) pose serious health and environmental risks. While existing toxic gas monitors are costly, two-dimensional (2D) materials have shown promise for gas sensing applications due to their high surface-to-volume ratios and sensitivity. Among these, α-CN has been identified as a potential candidate for gas adsorption mechanisms. This study investigates the adsorption performance α-CN surface with the decoration of nickel (Ni)-atom for CO, NO, and NH₃ toxic gases using state of art density functional theory (DFT) based first principles calculations. The results indicate that the Ni-decoration significantly enhances the adsorption performance of α-CN, as evidenced by highly negative adsorption energies. Therefore, the calculated recovery times are extremely long, suggesting that Ni-decorated α-CN is more suitable for the removal of these toxic gases rather than as a sensor. The structural and electronic properties, including projected density of states (PDOS), band structure, charge density diagrams and transfer mechanisms, have been thoroughly analyzed. Additionally, sensing properties such as work function and electrical conductivity, computed using semi-classical methods, have been evaluated to validate the effectiveness of the material.