Enhancing Dissociative Adsorption of Water on Cu(111) via Chemisorbed Oxygen

We have used X-ray photoelectron spectroscopy to study the dehydrogenation of H₂O molecules on the clean and oxygenated Cu(111) surfaces. The clean surface does not show reactivity toward H₂O dehydrogenation. By contrast, H₂O molecules on the oxygenated Cu(111) dissociate into OH species by reacting with chemisorbed oxygen until the complete consumption of the chemisorbed oxygen at which the surface loses its reactivity toward H₂O dehydrogenation. Increasing the temperature to 200 °C and above decreases molecularly adsorbed H₂O for dehydrogenation, thereby resulting in less loss of chemisorbed O. In conjunction with density-functional theory calculations, a three-step reaction pathway is proposed to account for the chemisorbed O assisted dehydrogenation of H₂O molecules and the net loss of surface oxygen. These results provide insight into understanding the elemental steps of the dehydrogenation of H₂O molecules and the controllable conditions for tuning H₂O dissociation on metal surfaces