The photocatalytic oxidation of methanol on a rutile TiO2(110) surface was studied by means of thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). The combined TDS and XPS results unambiguously identify methyl formate as the product in addition to formaldehyde. By monitoring the evolution of various surface species during the photocatalytic oxidation of methanol on TiO2(110), XPS results give direct spectroscopic evidence for the formation of methyl formate as the product of photocatalytic cross-coupling of chemisorbed formaldehyde with chemisorbed methoxy species and clearly demonstrate that the photocatalytic dissociation of chemisorbed methanol to methoxy species occurs and contributes to the photocatalytic oxidation of methanol. These results not only greatly broaden and deepen the fundamental understanding of photochemistry of methanol on the TiO2 surface but also demonstrate a novel green and benign photocatalytic route for the synthesis of esters directly from alcohols or from alcohols and aldehydes.

The interaction of atomic hydrogen and H 2 O with stoichiometric and partially reduced CeO 2 (111) thin films deposited on a Cu(111) substrate was investigated by temperature programmed desorption and X-ray photoelectron spectroscopy. On stoichiometric CeO 2 (111) surface, the adsorption of atomic H(g) leads to the formation of surface hydroxyl (OH(a)) and H 2 O(a) as well as the reduction of Ce 4+ into Ce 3+ . On reduced CeO 2 (111) surfaces, the stability of OH(a) was enhanced by the presence of oxygen vacancies. Upon heating, surface hydroxyls undergo two competing reaction pathways: one is the associative desorption of OH(a) releasing H 2 O and creating oxygen vacancies (OH(a) + OH(a) → H 2 O(g) + O lattice + O vacancy ), and the other one is to produce H 2 via OH(a) + OH(a) → H 2 (g) + 2O lattice . The presence of oxygen vacancies in CeO 2 favors the reaction pathway of H 2 formation. At 115 K, reversible dissociation and molecular adsorption of H 2 O occur on stoichiometric CeO 2 (111) surface, but irreversible dissociation of H 2 O occurs on reduced CeO 2 (111) surfaces. These results deepen the fundamental understanding of the influence of oxygen vacancies on the reactivity of surface hydroxyls and water on CeO 2 surface.

By rational design of the FeO(111)/Pt(111) inverse model catalyst and the control experiments, we report for the first time direct experimental evidence for the interfacial CO(ads) + OH(ads) reaction to produce CO(2) at the Pt-oxide interface at low temperatures, providing deep insights into the reaction mechanism and active site of the important low-temperature water-gas shift and preferential CO oxidation reactions catalyzed by Pt/oxide nanocatalysts at the molecular level.