Adsorption and dissociation of H2 on the Cu2O(1Â 1Â 1) surface: A density functional theory study

Interactions of atomic and molecular hydrogen with perfect and deficient Cu2O(1 1 1) surfaces have been investigated by density functional theory. Different kinds of possible modes of H and H2 adsorbed on the Cu2O(1 1 1) surface and possible dissociation pathways were examined. The calculated results indicate that OSUF, CuCUS and Ovacancy sites are the adsorption active centers for H adsorbed on the Cu2O(1 1 1) surface, and for H2 adsorption over perfect surface, CuCUS site is the most advantageous position with the side-on type of H2. For H2 adsorption over deficient surface, two adsorption models of H2, H2 adsorbing perpendicularly over Ovacancy site and H2 lying flatly over singly-coordinate Cu-Cu short bridge, are typical of non-energy-barrier dissociative adsorption leading to one atomic H completely inserted into the crystal lattice and the other bounded to CuCUS atom, suggesting that the dissociative adsorption of H2 is the main dissociation pathway of H2 on the Cu2O(1 1 1) surface. Our calculation result is consistent with that of the experimental observation. Therefore, Cu2O(1 1 1) surface with oxygen vacancy exhibits a strong chemical reactivity towards the dissociation of H2.