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

Abstract

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.