TiO2 nanoparticle modified α-Fe2O3 nanospindles for improved photoelectrochemical water oxidation

Surface modification is an effective way to improve the photoelectrochemical water splitting efficiency of Fe2O3 photoanode. Here, TiO2 nanoparticles were used to decorate on the surface of Fe2O3 spindles and formed Fe2O3/TiO2 core-shell nanostructures. After modification, small amount of Fe3+ doped into TiO2, creating oxygen vacancies at the interfaces of Fe2O3/TiO2 as confirmed by means of XRD, UV-vis, XPS and EPR. The TiO2 compact shells are composed of uniform nanoparticles with a size of 5-20 nm. Compared with pure Fe2O3, the Fe2O3/TiO2 displays enhanced photocatalytic activity for photoelectrochemical water splitting under visible light irradiation (lambda >= 420 nm). The photocurrent density of Fe2O3/TiO2 photoanodes was equal to 0.23 mA/cm(2) at 0.6 V (vs. Ag/AgCl), which is about 1.5 times as high as that of pristine Fe2O3. The high performances of the Fe2O3/TiO2 photoanode can be attributed to the better separation of electrons and holes caused by surface oxygen vacancies. The photocurrent densities under visible-light illumination of Fe2O3/TiO2 was further improved after high-temperature calcination owing to the increase of oxygen vacancies of the sample. This work may provide more insights to design new-type and efficient photoanodes for PEC applications.