Theoretical study of direct versus oxygen-assisted water dissociation on the Cu(1 1 0) surface

Abstract

Density functional theory (DFT) calculations have been employed to investigate the adsorption of water (H2O) on Cu(110) surface and the corresponding dissociation reaction. The equilibrium configurations of H2O adsorption on the top, bridge and fcc sites were determined by relaxation of the system. H2O is found to be adsorbed preferably on the top site of Cu(110) surface, OH and O are easily adsorbed on the bridge site, while H favors both bridge and fcc sites. The adsorption is attributed to the interaction between the p orbitals of the adsorbates and the d orbitals of the copper atoms, predominantly on the top layer of the Cu(110) surface. The dehydrogenation of H2O on clean and oxygen-covered copper surfaces was both investigated, and we find that the energy barriers for H–OH and O–H dissociation, which is 162.51 and 230.43kJmol−1 on clean copper surface, decreases to 27.05 and 162.88kJmol−1 with the aid of pre-adsorbed O atom (Oads), respectively. These results indicate that the energy barrier of dehydrogenation on the oxygen-covered copper surface is remarkably lowered and Oads can effectively promote H2O decomposition.