Enhanced photovoltaic and photoelectrocatalytic properties by free-standing TiO2 nanotubes via anodization

This work employs a simple anodization to develop free-standing TiO2 nanotubes with controllable sizes via a self-detaching technique, and the resulting close-bottom-up free-standing TiO2 nanotubes are faced Degussa P25 particle film, precoated on a fluorine-doped SnO2 conductive glass, to fabricate a TiO2 composite. The resulting composites, whose sizes can be controlled by modulating the reanodizing time, were used as the photoanode films and oxidative catalyst to investigate their corresponding photoelectrochemical properties. Compared with P25 particle film, these resulting composites reveal the improved photocatalytic and photovoltaic performance, which results from the effective transfer of photo-generated charges by these characteristic nanotubular arrays. The composite, based on the free-standing TiO2 nanotubes (similar to 10.88 mu m), indicates the highest photovoltaic conversion efficiency (7.64 %) under a standard AM 1.5 solar simulator and degradation rate (95.20 %) under the UV irradiation of 75 min, and these results are probably attributed by the positive synergistic effect of the transport of photo-generated charges, the diffusion path of reactants, and the penetration length of incident light into films in comparison to other free-standing TiO2 nanotubes. In addition, the higher photoelectrocatalytic activity is acquired by electrochemically assisted photocatalytic degradation.