ZnSnO3-derived ZnSnO3/ZIF-8 composites with enhanced adsorption and photocatalytic activity in RhB degradation and CO2 reduction.

This study aims to increase the photoactivity of ZnSnO3 by modifying it with zeolitic imidazolate framework-8 (ZIF-8). The composite catalyst was prepared by a straightforward hydrothermal method using ZnSnO3 as the zinc source. The in-situ generated ZnSnO3/ZIF-8 composite exhibits a strong interaction between ZnSnO3 and ZIF-8, which benefits electron transfer. Band structure analysis shows that ZIF-8 has a higher conduction band and a lower valence band than ZnSnO3, and cannot form a typical heterojunction. However, defects in ZIF-8 may act as electron traps, accepting electrons from the conduction band of ZnSnO3. This atypical heterojunction results in the spatial separation of charge carriers within the composite. The transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence analysis confirmed this hypothesis. Meanwhile, ZIF-8 also plays a role in adsorbing dyes and concentrating reactants due to its extremely high specific surface area. Therefore, the ZnSnO3/ZIF-8 composite exhibits significantly improved photocatalytic performance in Rhodamine B degradation. The degradation rate of the best sample was 10.4 times that of ZnSnO3. Active species capture experiments showed that holes and superoxide radicals were the main active species. Additionally, the ZnSnO3/ZIF-8 composite showed enhanced photocatalytic activity in CO2 reduction. This study may show new insights into the design of efficient photocatalytic materials using metal-organic framework materials.