Enhanced photocatalytic activities of ZnO/Bi2O3 hollow composites via the Z-scheme mechanism through p–n heterojunctions

Constructing Z-scheme heterojunctions by establishing a unique charge transfer pathway at the interface has garnered growing attention in photocatalytic technology. In this study, a p-n heterojunction of Z-scheme was developed by employing an in-situ annealing strategy following the electrostatic self-assembled chemistry, with n-type ZnO and p-type Bi 2 O 3 as the constituent materials. Upon AM 1.5 G irradiation, the optimal ZnO/Bi 2 O 3 (Zn/BO) photocatalysts achieved a remarkable H 2 -evolution reaction (HER) rate of 458.3 μmol∙h −1 , which was 10.5 times higher than that of the original ZnO and 5 times higher than that of Bi 2 O 3 , respectively. Moreover, its efficiency in degrading 100 mg∙L −1 rhodamine B (RhB) reached 100% within a 60-minute period. Its rate constant was 24.70 and 11.71 times higher compared to ZnO and Bi 2 O 3 , respectively. The proposed Z-scheme mechanism of electron transfer was put forward to explain the observed enhancement in photocatalytic performance, as determined by in-situ XPS experiments. Furthermore, the Zn/BO photocatalyst exhibited exceptional catalytic activity when exposed to visible light (λ > 420 nm). The remarkable cycle stability of the hollow Z-scheme catalyst further suggests its potential for facilitating the industrialization of photocatalytic technology.