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

Density functional theory (DFT) calculations have been employed to investigate the adsorption of water (H 2 O) on Cu(1 1 0) surface and the corresponding dissociation reaction. The equilibrium configurations of H 2 O adsorption on the top, bridge and fcc sites were determined by relaxation of the system. H 2 O is found to be adsorbed preferably on the top site of Cu(1 1 0) 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(1 1 0) surface. The dehydrogenation of H 2 O 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 230.43 kJ mol −1 on clean copper surface, decreases to 27.05 and 162.88 kJ mol −1 with the aid of pre-adsorbed O atom (O ads ), respectively. These results indicate that the energy barrier of dehydrogenation on the oxygen-covered copper surface is remarkably lowered and O ads can effectively promote H 2 O decomposition. [ABSTRACT FROM AUTHOR]