Adsorption of Gas Molecules on Graphene-Like ZnO Nanosheets: The Roles of Gas Concentration, Layer Number, and Heterolayer.

2D layered materials have gained tremendous research interests for gas sensing applications because of their ultrahigh theoretical specific surface areas and unique electronic properties, which are prone to be influenced by external factors. Here, using first principle calculations, the adsorption of several common gas molecules on graphene-like ZnO (g-ZnO) is systematically studied by taking the gas concentration, homolayer number, and heterolayers into considerations. The calculation results show that the adsorption energies of all the selected gas molecules are susceptible to the concentration and the homolayer number, and they incline to gradually increase with the decreasing of the gas concentration or they dramatically increase with the raising in g-ZnO layer number combined with elevated charge transfers. Besides, choosing graphene (MoS₂) as a heterolayer material to stack with g-ZnO can enhance (weaken) the interaction with NH₃ (NO₂) while weakening (enhance) that of NO₂ (NH₃), thus facilitating the selectivity to some extent. Further, Hirshfeld charge analysis and visualization of the charge density differences between the layers reveal the different charge transfers and adsorption mechanisms before and after gas adsorption. The results indicate that g-ZnO and its homolayer and hetero-bilayer structures can be promising candidates as gas sensing materials and catalysis. [ABSTRACT FROM AUTHOR]