Extraordinary effects of an argon atmosphere on TiO2 photocatalysis

Abstract

When used as a photocatalyst under solar light, TiO₂ tends to show a low photocatalytic activity. We report here that even TiO₂ exhibits a high photocatalytic activity toward the decomposition (mineralization) of aqueous organic contaminants under simulated solar light when used under an Ar atmosphere (Ar flow). The photocatalytic decomposition rate of a cationic dye, crystal violet, and the CO₂ evolution rate over TiO₂ (P25, mainly composed of anatase and rutile) under Ar flow were substantially higher than those obtained in air and under air, O₂, N₂ and CO₂ flows. Similar positive effects of Ar flow on photocatalytic reactions were observed when another cationic dye, basic violet 4, and TiO₂ (anatase) were used, suggesting the versatility of Ar flow for improving photocatalytic activities.