Construction of a TiO2 heterostructure nanowire with a sulfurized shell via a simple sulfurization process for enhanced photoelectrochemical water oxidation

Abstract Promoted charge transport and separation as well as excellent light harvesting ability play a key role in enhancing photoelectrochemical (PEC) performance. Herein, a simple sulfurization approach was developed for forming polycrystalline S-doped TiO2 shell on the single crystalline TiO2 nanowire surface to form the TiO2/S-doped TiO2 core-shell homostructure. With the sulfurization time, the light harvesting ability, separation efficiency and carrier density increased for such homostructures. As a result, the highest photocurrent densities of 1.24 mA/cm2 at 1.23 V versus RHE was achieved over the TiO2/S-doped TiO2 core-shell homostructure sulfurized for 15 h, corresponding to 67.6% improvement in photocurrent density compared with the pristine TiO2. This work reveals a relatively simple strategy to simultaneously enhance light absorption and electron-hole pair separation.