High-efficiency SrTiO3/TiO2 hetero-photoanode for visible-light water splitting by charge transport design and optical absorption management.

Herein, a two-pronged approach to obtain excellent visible-light performance of SrTiO3/TiO2 photoelectrodes for water oxidation is presented. More specifically, the combination of hetero-constructing SrTiO3 nanocubes and Cr3+/Ti3+ dual-doping has been demonstrated for achieving high efficiency of charge separation and extending photoresponse of TiO2 nanotube arrays from the UV to visible light region. As expected, this unique Cr-SrTiO3-x/Cr-TiO2-x photoanode exhibited remarkably improved PEC performance for water splitting (4.05 mA cm-2) under visible light irradiation, which is more than 100 times higher than that of pristine TiO2 nanotube arrays. Additionally, the photocurrent intensity as well as water splitting behavior remain constant even after long time irradiation, revealing its high PEC as well as structure stability. Thereby, the rational design of the interface charge transport and precise management of optical absorption endow the TiO2-based PEC system with excellent and stable visible-light performance for water splitting.