Fe2O3 nanothorns sensitized two-dimensional TiO2 nanosheets for highly efficient solar energy conversion

Abstract

The hybrid structure of Fe2O3 nanothorns/TiO2 nanosheets photoanodes is reported in the work for the first time. Two-dimensional TiO2 nanosheets array films are grown on transparent conductive fluorine-doped tin oxide glass substrate by simple hydrothermal method. The Fe2O3 nanothorns uniformly deposited on the TiO2 backbone are prepared by chemical bath deposition followed by annealing. The phase structure, morphology and optical properties of the heterogeneous composite films are characterized by X-ray diffraction pattern, scanning electron microscopy and UV–visible spectroscopy. Different nanostructured Fe2O3/TiO2 heterostructures are also investigated by controlling the reaction time of the chemical bath deposition. The two-dimensional TiO2 nanosheets provide an extremely porous matrix and high-activity area required for deposition of Fe2O3 sensitizer. The optimal photocurrent density of Fe2O3/TiO2 film reaches 2.50mA/cm2 and the photoconversion efficiency is 1.25%, which is more than six times higher than that of bare TiO2 film (0.2%). The results indicate that the photogenerated carriers can separate and transfer more easily in Fe2O3/TiO2 films due to the type-II band structures formed at the interface between TiO2 and Fe2O3. The Fe2O3/TiO2 heterogeneous films have potential applications in photoelectrochemical solar cells or water splitting.