Nanostructured Iron-Titanium Oxide Aerogel Photocatalysts for Energy Conversion
Chien-Tsung Wang, Chemical Engineering Department, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou, Yunlin, Taiwan
Semiconductor metal oxides play a promising role of photocatalysts when they are applied to the solar energy conversion and storage process. Under light irradiation, the catalytic oxidation of an organic fuel in electrolyte by photo-generated holes determines the photo-charging potential at open-circuit conditions. In the dark, electrical discharging is controlled by the re-oxidation capability of the catalytic material. The present study aims to demonstrate photoelectrochemical energy conversion and storage capability of reducible iron and titanium oxides. The oxide catalysts were prepared by the aerogel approach with supercritical drying, and photoelectrochemical measurements were carried out in a quartz cell with UV or visible illumination. The aerogel powders possess primary particle sizes ranging from 15 to 40 nm, as measured by HRTEM. The photo-charging potential was dependent upon light intensity, hole scavenger and concentration, and electrode temperature. Pure titania exhibited the most prompt response to light irradiation on and off, and the iron oxide species enhanced energy storage. The mixed Fe-Ti oxide showed the highest discharging capacity.