ZnO Nanostructures for Gas Sensing: Interaction of NO2, NO, O, and N with the ZnO(101̅0) Surface

Abstract

The adsorption of NO2, NO, and atomic N and O on the clean ZnO(1010) surface is examined using density functional theory and ab initio molecular dynamics simulations. Adsorption of NO2 is also investigated on a defect surface containing an O vacancy. Calculated binding energy values, Bader charges, vibrational frequencies, density of states, planar averaged charge density differences, and electron localization plots are presented. Both the molecular and atomic adsorbates are found to adsorb in multiple minimum-energy sites with NO2 and NO preferring to weakly adsorb on surface Zn sites, while O and N chemisorb in highly coordinated surface sites forming an O2 and NO surface species, respectively. The presence of atomic O or N on the surface causes significant structural changes to the surface geometry. All adsorbates can induce magnetism on the surface, with the distribution of the magnetic moment being highly dependent on the adsorption geometry. The adsorbates behave as electron acceptors, withdrawing ...