H2O Absorption on Mono and Multilayer Zinc Oxide Nanoribbon: A First Principles Study

Abstract

In this paper, ZnO monolayer and multilayer nanoribbon, isolated and with water molecule are studied based on first principles ab-initio density functional theory. Water absorption is investigated in optimum distance between water molecule and ZnO nanostructures surfaces. Absorption energies indicate that water molecule is physically absorbed on both structure surfaces. Moreover, Mulliken analysis shows that water molecule takes electron from both nanostructures. The projected density of states is investigated for all structures. Results depict water molecule has less tendency to stick to ZnO monolayer nanoribbon surface in comparison to ZnO multilayer nanoribbon surface. Projected density of states represent that hybridization occurs between 2p orbital of oxygen atom in water molecule and 4s orbital of zinc atom. The density of states is calculated for isolated ZnO nanostructures and water absorbed ZnO configurations. Simulation results represent the band gap is about 2 eV and 1.16 eV for ZnO mono and multi nanoribbon, respectively. Consequently, the better H 2 O absorption behavior of ZnO monolayer nanoribbon structure allows using this structure in different applications, such as self-cleaning coating and humidity sensors.