Carbon coupling on titanium oxide with surface defects

Oxide materials with surface defects have in recent years been shown to considerably influence their gas-surface reactions. In this work we show that while CO2 is weakly adsorbed on the "stoichiometric" {011}-faceted surface of TiO2 (0 0 1) single crystal it becomes strongly adsorbed once surface defects are created and further reacts. Intentionally creating oxygen vacancies by sputtering with hydrogen (or deuterium) ions had a dramatic effect on CO2 reaction. TPD Of CO2 showed the formation of ethylene in large amounts. This coupling reaction is initiated by the O abstraction from CO2 to regenerate surface oxygen ions. The remaining adsorbed molecule (CO like molecules) couples to make the olefin as in the case of organometallic chemical reactions. (C) 2004 Elsevier B.V. All rights reserved.