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

Abstract

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 Bi2O3 as the constituent materials. Upon AM 1.5 G irradiation, the optimal ZnO/Bi2O3(Zn/BO) photocatalysts achieved a remarkable H2-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 Bi2O3, 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 Bi2O3, 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.