Synergistical Dual Strategies Based on in Situ-Converted Heterojunction and Reduction-Induced Surface Oxygen Vacancy for Enhanced Photoelectrochemical Performance of TiO₂

Identifying effective means to improve the charge separation performance assisted by adequate surface reaction represents a significant challenge for developing a highly efficient TiO2 photoanode. Here we report a structural synergistic strategy between a close contact heterojunction and a surface oxygen vacancy to significantly boost the charge separation efficiency and charge injection efficiency of TiO2 nanowires (NWs) in PEC water splitting. To accomplish this task, a TiO2/SrTiO3 (TiO2/STO) heterojunction was first constructed by in situ conversion, resulting in close contact between interface, promoting separation of the photoinduced charge carriers, which increased charge separation efficiency by 107% compared to TiO2. After the amorphous layer was established on the surface of the SrTiO3 coating, the resulting TiO2/SrTiO3/r-SrTiO3 (TiO2/STO/r-STO) improved the light absorption property of the photoelectrodes and boosted the ability to adsorb the reactant hydroxide ions, resulting in charge injection efficiency improvement by 67.3% compared with pure TiO2. This complementary modification for enhancing charge separation and boosting the surface reaction demonstrates a significant capacity to improve the photoelectrochemical (PEC) performance of one photoanode, which could be instructive for other fields including photocatalysis and PEC carbon dioxide reduction.