Adsorption studies on titanium dioxide by means of Raman spectroscopy

The use of the Raman spectroscopy as a technique providing microscopic (vibrational) information on organic adsorbates at the semi conductor/solution interface is illustrated. First, a way of extending surface enhanced Raman spectroscopy to nanostructured thin films of anatase is presented and validated with experiments of phthalic acid adsorption. The procedure, based on the enhancement provided by a roughened gold substrate, is then applied to the cases of formic acid and methanol and the results linked to mechanistic aspects of their photoelectrocatalytic oxidation processes. Formic acid is shown to specifically adsorb on anatase as formate, while methanol does not seem to interact strongly with the TiO2 surface. Secondly, we take advantage of resonance scattering to study the adsorption and photoreactivity of salicylic and ascorbic acids on nanostructured thin films and concentrated slurries of TiO2 Both organics seem to form chelating adspecies, which react under the visible laser irradiation used as Raman probe. To cite this article: T Lana-Villarreal et al., C R. Chimie 9 (2006). (C) 2005 Academie des sciences. Published by Elsevier SAS. All rights reserved.