Gas capture and selective sensing performance of graphene-like AlNC₂ monolayer: a DFT study

The gas adsorption behavior of a recently proposed graphene-like AlNC₂ monolayer was systematically investigated using density functional theory calculations. The structural stability of the AlNC₂ sheet was confirmed using cohesive energy calculations and phonon dispersion spectrum analysis. The interaction of several environmentally harmful gases including CO, NO, NO₂, SO₂, NH₃, H₂S, and CH₄ with the AlNC₂ surface was examined by calculating adsorption energies, charge density difference, work-function changes, density of states, and recovery times. The calculated adsorption energies indicated strong chemisorption for NO₂, SO₂, NO, and NH₃, while CO and H₂S exhibited moderate interactions. The CH₄ interacted only weakly with the surface. Charge redistribution and work function analysis revealed various acceptor- and donor-type adsorption behaviors depending on the nature of the gas molecule. Noticeable changes in the electronic structure, including band-gap narrowing and the appearance of new states near the Fermi level were observed for strongly adsorbed gas molecules. These finding were confirmed by density of state plots and charge density difference analyses. Recovery time values showed that AlNC₂ exhibits reversible adsorption behavior for moderately adsorbed gas molecules. Moreover, strongly chemisorbed species exhibited difficult desorption at ambient temperatures, indicating the potential of the AlNC₂ for gas capture and removal.