Photoemission study on the adsorption of ethanol on clean and oxidized rutile TiO2 (110)-1 x 1 surfaces

Synchrotron radiation photoemission spectroscopy is employed to study the adsorption of ethanol on the rutile TiO2(110) surface at room temperature (RT). For the present study, well-characterized clean and oxidized rutile TiO2(110) surfaces are reproduced and ethanol is subsequently dosed at RT. We observe that the bandgap state varies in intensity upon ethanol adsorption on TiO2(110) at RT. Especially, the band-gap state is enhanced in intensity when ethanol is dosed on the oxidized TiO2(110) surface. These observations imply that the adsorption of ethanol induces a change in the surface charge associated with defects such as oxygen vacancies and Ti3+ interstitials due to an attractive interaction between ethanol and such defects. Interestingly, pre-dosed ethanol on TiO2(110) is observed to inhibit the attenuation of the band-gap state during subsequent O-2 dose at RT. We interpret the result from a site-blocking effect by the pre-adsorbed ethanol both on oxygen vacancies and Ti4+ sites in inhibiting the interaction between O-2 and surface defects on the TiO2(110) surface. 2011 Elsevier B.V. All rights reserved.