Theoretical investigation of gas–sensing properties of ZnO nanosheets

Abstract

The structure optimizations of all configurations of gaseous O₂, CO, NO, NO₂, N₂O, NH₃, H₂ and H₂O molecules adsorbed on ZnO nanoclusters (ZnONCs), aromatic–like (AL–ZnONC), naphthalene–like (NLL–ZnONC), pyrene–like (PRL–ZnONC) and ZnO graphene–like nanosheets (ZnOGLNSs), coronene–like (CNL–ZnONS) and circumcoronene–like (CCL–ZnONS) were carried out using the B3LYP/LanL2DZ calculations. Adsorption energies of these gases on AL–ZnONC, NLL–ZnONC, PRL–ZnONC, CNL–ZnOGLNS and CCL–ZnOGLNS were reported. It was found that only O2 was chemically adsorbed via the hydride atoms of zinc–hydride in the ZnONCs and ZnOGLNSs whereas the other gases are not. In terms of physisorptions, only O₂ molecule was adsorbed over the plane of ZnOGLNSs. As the energy gaps of ZnOGLNSs were largely reduced after adsorption of O₂, NO or NO₂, these ZnOGLNSs were therefore be the sensing materials for there gases. It was found that adsorption of CO, H₂, H₂O, NH₃ and N₂O on ZnOGLNSs were somewhat weak, and thus these ZnOGLNSs were hardly sensing to these gases.