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

• The results give a specific explanation of using atomic oxygen to modify clean Cu (111) surface.
• It is found that the presence of oxygen atom on the Cu (111) surface can promote the dissociation of H2O.
• There is a negative correlation between the promoted effect of pre-adsorbed oxygen atom and the adsorption energies.

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.