Simultaneous Storage of Oxidative and Reductive Energy Generated at a UV-Irradiated TiO2 Photocatalyst

Nanostructured TiO2-Ni(OH)(2) composite film and WO3 nanoflake array electrodes are prepared by a facile hydrothermal synthesis-electrodeposition procedure or a solvothermal technique, respectively. A novel storage system for oxidative and reductive energy generated at a UV-irradiated TiO2 photocatalyst is first constructed by galvanically coupling the as-prepared TiO2-Ni(OH)(2) composite film and the WO3 film electrodes. The as-constructed system exhibits excellent simultaneous storage ability for UV-induced oxidative and reductive energy, and the apparent quantum yield is as high as 7.8%. The coupling of the UV-irradiated TiO2-Ni(OH)(2) composite film with the WO3 nanoflake array electrode in the dark decreases the hole-electron recombination and the reduction of NiOOH, leading to both the realization of the reductive energy storage and the enhancement of the oxidative energy storage. Based on the obtained experimental results, a possible mechanism for simultaneous storage of UV-induced oxidative and reductive energy is proposed. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.055207jes] All rights reserved.