Charge-discharge behavior of TiO2-WO3 photocatalysis systems with energy storage ability

TiO2 coupled with WO3 has been reported as an energy storage photocatalyst, which functions partially even in the dark. The WO3 can be charged with reductive energy generated at the TiO2 under UV light illumination. In this work, charge-discharge behavior of the TiO2-WO3 films in air was studied and compared with that in liquids (0.1 M NaCl and water). Charging rate, discharge capacity, apparent quantum yield and self-discharging rate for electron storage were evaluated. In the charging of the TiO2-WO3 film in air, humidity controls those factors when the UV light intensity was 10 mW cm(-2), where photon supply does not solely control the charging process. The adsorbed water layer on the film should play an important role in the charging process, via the proton conduction at the film surface and water supply for the anodic reaction.