Adsorption and dissociation of H 2 on the Cu 2O(1 1 1) surface: A density functional theory study

Abstract

Interactions of atomic and molecular hydrogen with perfect and deficient Cu 2O(1 1 1) surfaces have been investigated by density functional theory. Different kinds of possible modes of H and H 2 adsorbed on the Cu 2O(1 1 1) surface and possible dissociation pathways were examined. The calculated results indicate that O SUF, Cu CUS and O vacancy sites are the adsorption active centers for H adsorbed on the Cu 2O(1 1 1) surface, and for H 2 adsorption over perfect surface, Cu CUS site is the most advantageous position with the side-on type of H 2. For H 2 adsorption over deficient surface, two adsorption models of H 2, H 2 adsorbing perpendicularly over O vacancy site and H 2 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 Cu CUS atom, suggesting that the dissociative adsorption of H 2 is the main dissociation pathway of H 2 on the Cu 2O(1 1 1) surface. Our calculation result is consistent with that of the experimental observation. Therefore, Cu 2O(1 1 1) surface with oxygen vacancy exhibits a strong chemical reactivity towards the dissociation of H 2.