Semiconductor-based solar water splitting is a promising strategy for the production of fuels from a clean and sustainable source, following the global trend of replacing fossil fuels. Herein, a systematic study of the application of single-phase pseudobrookite Fe2TiO5 nanoparticles as oxygen-evolving photocatalyst for water splitting, in a suspended particle system, is presented. A solvothermal route was employed for the synthesis of Fe2TiO5 nanoparticles with average diameter of (34 ± 8) nm. The obtained orange powder absorbs a broad portion of the solar spectrum (band gap of 2.1 eV) and produces 7.0 μmol of O2 within 5 h, under visible light irradiation. In order to enhance the catalytic activity of Fe2TiO5, NiO and Co3O4 cocatalyst nanoparticles were, separately, attached to the surface through the conventional impregnation and the magnetron sputtering deposition (MSD) methods. The homogeneous coverage with cocatalysts nanoparticles provided by the latter, allied to the reduced dimensions of the formed oxide nanoparticles (∼1 nm), resulted in an enhanced photoactivity of Fe2TiO5. The Co3O4-modified materials prepared through magnetron sputtering and impregnation depositions produced 58.8 and 26.2 μmol of O2 within 5 h under visible light, respectively. Similar behavior was observed for the NiO-modified nanomaterial, which generated 25.5 and 12.6 μmol of O2, respectively. These results reflect the potentiality of Fe2TiO5 nanoparticles to be employed as a particulate water splitting photocatalyst, especially when containing homogeneously distributed nanoparticles of the Co3O4 cocatalyst on the surface. Photoelectrochemical measurements further confirmed these conclusions, as Co3O4 and NiO fine deposits substantially reduce the water oxidation overpotential of a Fe2TiO5 photoanode and enhance the intensity of the anodic photocurrent due to the improved oxidation kinetics, the reduced charge recombination rates, and the lowered charge transfer resistance at the solid/liquid interface.

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Since Honda & Fujishima discovered the photolysis of water phenomena in 1972, researchers have been trying to obtain semiconductors materials with appropriated band structure to artificial photosynthesis. However, many semiconducting materials suffer from recombination of charge carrier that reduces their efficiency. Several strategies can be employed in order to improve these materials, such as: nanostructure fabrication, heterojunction and doping. Herein, we synthetized a heterojunction of SrTiO3 on TiO2 nanotubes, as well doping this structure with Lanthanum ions. To obtain TiO2 nanotubes, metallic titanium was anodized at room temperature. Heterojunction and doping were obtained by hydrothermal reaction. The morphology and crystallinity changed according to the hydrothermal time. In long durations, it observed an excessive grain growth, while short duration created a nonstoichiometric SrTiO3 structure. This structure was ascribed by the band gap reduction and cationic vacancies states in XPS. Nevertheless, the sample doped with lanthanum ions balanced the formation of the disordered structure, thereby increasing the charge carrier density. The photoelectrochemical measurements showed higher photocurrent density when the sample was doped with 10% lanthanum ions during 30 minutes on hydrothermal reactor. These findings provide an overview in how efficiently modify 1D structure and how the doping alters the charge carrier properties on heterojunctions produced by hydrothermal treatment.