Surface Chemistry Of TiO2 Research Articles

Chemisorption Determines the Photovoltage of a Ti/TiO2/Au/Dye Internal Electron Emission Photovoltaic Cell

The Ti/TiO2/Au junction forms the basis of a promising new type of photovoltaic cell, provided that a light-harvesting antenna layer can be deposited on the thin gold film. We report that the electrical diode characteristics of the TiO2/Au Schottky barrier deteriorate by deposition of a hydrophobic quantum dot film, Merbromin dye adsorption, or electron-hole photogeneration in TiO2 under inert conditions. In the presence of oxygen and water vapor, the Schottky barrier characteristics and high photovoltage are recovered. The strong influence of the TiO2 surface chemistry on the (photo)electrical characteristics of the solar cell is discussed on the basis of an existing microscopic model.

Characterization of silicated anatase powders

Silicated titanias have been prepared by reaction of commercial anatase-based TiO2 powders with tetraethylorthosilicate, followed by calcination. At low loadings orthosilicate species are found, that interact mainly with surface defects of anatase where surface hydroxy groups are located. At higher loadings polysilicate species are found, while amorphous silica is observed if the nominal loading is comparable to that allowing the coverage of the entire TiO2 surface with a silicate layer. Surface silicate species progressively mask the TiO2 surface, and do not generate Bronsted acidity that is sufficiently strong to protonate pyridine. Silication strongly hinders anatase crystal growth and loss of surface area upon heating, as well as the anatase-to-rutile phase transformation. Thus, supported silica in small amounts can act as an efficient morphology and structure promoter of anatase TiO2-based catalysts, although it also perturbs the TiO2 surface chemistry significantly.