Molecular and dissociative O2 adsorption on the Cu2O(111) surface

Abstract

The adsorption of O₂ on the Cu₂O(111) surface at different coverages has been studied by spin-polarized density functional theory (DFT+U) calculations and atomic thermodynamics. It has been found that the dissociative O₂ prefers to adsorb on the reconstructed Cu₂O(111) surface at low coverages (1/4 to 1 monolayer), while totally dissociative and mixed molecular and dissociative O₂ prefers to adsorb on the reconstructed Cu₂O(111) surface thermodynamically at higher coverages (5/4 to 7/4 monolayers). More interesting is that the CuO film can be automatically formed on the Cu₂O(111) surface that was induced by the surface reconstruction of the Cu₂O(111) surface and adsorption of four dissociative O₂ molecules (1 monolayer), which agrees well with the recent experimental results. Along higher coverages of O₂ adsorption (5/4 to 7/4 monolayers), much stronger surface reconstruction and relaxation was found. The probability distribution of different single-O₂ adsorbed states on the Cu₂O(111) surface as a function of temperature was analyzed using a Boltzmann model. The adsorption mechanism of O₂ on the Cu₂O(111) surface was analyzed using the phase diagram and compared with other metal oxides.