Stannous oxide promoted charge separation in rationally designed heterojunction photocatalysts with a controllable mechanism

Due to the sluggish mobility of holes, the low charge-separation rate remains an intrinsic issue that limits further increase of the photocatalytic conversion efficiency. Herein, we proposed an in situ hydrothermal method to expedite the charge transfer with enhanced photocatalytic H2 evolution rate and photodegradation activities via introducing SnO microplates into TiO2. As compared to bare TiO2, the SnO/TiO2 heterojunction achieves remarkable 470% and 150% higher efficiency for the photocatalytic H2 evolution rate and photodegradation of rhodamine B, respectively. In particular, it is demonstrated that the charge transfer mechanism of SnO/TiO2 can be switched from the Z-scheme to type II by Pt loading, leading to a significant enhancement of photocatalytic performances. Furthermore, the photocatalytic H2 evolution activities of ZnO and C3N4 can also be improved by introducing SnO via simple mechanical mixing. This work provides not only a new versatile stimulant for enhancing photocatalytic activities but also in-depth understanding of the charge transfer mechanism of heterointerfaces of semiconductors.