Fabrication of novel S-scheme ZnO/BaTiO₃heterostructured nanocomposite and their enhanced photocatalytic performance

It is of great significance to explore stable and efficient heterostructured nanocomposite photocatalysts to promote the degradation of organic pollution. In this study, ZnO/BaTiO₃(ZnO/BT) nanocomposite was successfully prepared by simple calcination treatment using ZnO and BT as precursors. The chemical reaction equation for the formation of ZnO/BT nanocomposite was introduced for the first time. The formation mechanism of ZnO/BT nanocomposite was proposed, namely the dissolution-deposition reaction. Among them, when the ZnO mass content was 17 % (17 wt% ZnO/BT), the nanocomposite exhibited the best photocatalytic performance. After being irradiated by ultraviolet–visible light (UV–vis) for 30 min, it could completely degrade methyl blue (MB). The photocatalytic rate constants of 17 wt% ZnO/BT nanocomposite are 14.4 times and 1.8 times that of BT and ZnO, respectively. The carriers of ZnO/BT nanocomposite migrated along the S-scheme trajectory by the internal electric field and energy band bending, which improved the carrier separation efficiency, retained the holes and electrons with high redox potentials. In addition, the nanocomposite photocatalyst showed good cyclability in four cycles, maintained its excellent photocatalytic performance, and showed excellent application prospects. Finally, based on liquid chromatography-mass spectrometry analysis, the pathway of the photocatalytic degradation of MB by ZnO/BT nanocomposite was proposed. The as-prepared ZnO/BT nanocomposite is an economical, stable and efficient photocatalyst, which is expected to be further used for practical wastewater treatment. This study provides a new approach for the design of efficient composite photocatalysis.