Dissociation mechanism of H₂O on clean and oxygen-covered Cu (111) surfaces: A theoretical study

Using the first-principles calculations method based on the density functional theory, the adsorption and dissociation of water on clean and oxygen-covered Cu (111) surface have been investigated systematically. According to the theoretical calculations results, it was found that H₂O prefers to adsorb on the top site, while OH, O and H are favorable on the fcc site. In addition, the structures of the transition states, the corresponding energy barriers and reaction energies were determined. A feasible mechanism on oxygen-covered Cu (111) surface for complete dissociation of H₂O was also put forward. The results showed that the activation barrier for H₂O dissociation decreases obviously with the aid of the oxygen atom. It was proposed that the presence of oxygen atom on the Cu (111) surface can promote the dissociation of H₂O. Compared with our previous reports on Pd and Au surfaces, It was found that a negative correlation exists between the promoted effect of pre-adsorbed oxygen atom and the adsorption energies on the corresponding surfaces. The results may be useful for computational design, modification and optimization of Cu-based catalysts.