Photocatalysis and photoelectrocatalysis using nanocrystalline titania alone or combined with Pt, RuO2 or NiO co-catalysts

Abstract

Photocatalytic mineralization of ethanol in the presence of oxygen has been studied in aqueous photocatalyst suspensions by employing either pure nanocrystalline titania or TiO2 combined with Pt, RuO2 or NiO co-catalysts. Combined photocatalysts demonstrated a diverse behavior. Highest mineralization rates were obtained with Pt/TiO2 and lowest with RuO2/TiO2 and NiO/TiO2. These results were related with the photocatalysts’ behavior when used as photoanodes for the production of electricity in a photoactivated fuel cell running with ethanol as fuel. The highest current was obtained with pure titania. The current dropped in the case of Pt/TiO2 and became much lower in the case of RuO2/TiO2 and NiO/TiO2 photoanodes. Both current and voltage were lower in the presence of oxygen than in its absence. It is concluded that the presence of electron scavengers, like O2, and/or the use of efficient photocatalysts, like titania-supported Pt, yield less electric power but assist ethanol mineralization process.