Density functional study of adsorptions of CO 2 , NO 2 and SO 2 molecules on Zn(0002) surfaces

We report on a theoretical study of adsorptions of CO 2 , NO 2 and SO 2 molecules on ZnO(0002) surfaces using density functional theory-based (DFT-based) calculations. These adsorptions are done on perfect and defective ZnO(0002) surfaces. We find that all of these molecules are chemically adsorbed on the perfect ZnO(0002) surface. In the presence of Zn vacancy, we find that the surface is only active toward SO 2 molecule. On the hydroxylated ZnO(0002) surfaces, CO 2 and SO 2 molecules can react with the preadsorbed OH molecule to form various adsorbates such as: carboxyl (COOH), bicarbonate (CO 3 H), sulfonyl hydroxide (SO 3 H), SO 3 and water. However, NO 2 molecule cannot react with the pre-adsorbed OH molecule and only physically adsorbed on the surface.