Photocharge-discharge behaviors of hybrid WO3/TiO2 film electrodes -: Conversion, storage of electrons, and the effect of the WO3 structure on rechargeability

Photoelectrochemical energy conversion and electron storage were investigated on hybrid WO3/TiO2 film electrodes. Photoexcitation of WO3/TiO2 was observed to undergo charge accumulation, i.e., double injection of electrons and protons into WO3 to form tungsten bronze by the oxidation of oxalic acid or methanol to form CO2. It was clearly indicated that hybrid WO3/TiO2 involving highly dispersed WO3 (an amorphous-like WO3 phase) exhibits more effective reversibility for photocharge-discharge processes than a hybrid involving a bulk polycrystalline WO3. The energy band structure and phase changes of WO3 into tungsten bronze (H0.23WO3 and H0.33WO3) by photocharge or electrocharge of the hybrid WO3/TiO2 have also been characterized. (c) 2006 The Electrochemical Society. [DOI: 10.1149/1.2404777] All rights reserved.