ZnO@ZIF-8 core–shell heterostructures with improved photocatalytic activity

Abstract

ZnO semiconductors have been widely used as photocatalysts. However, the weak photodegradation under solar light restrains their further application. In this study, porous zeolitic imidazolate framework-8 (ZIF-8), which has a high specific surface, was combined with ZnO nanorods to fabricate ZnO@ZIF-8 core–shell heterostructures, with the ZnO nanorods and ZIF-8 as the core and the shell, respectively. Scanning electron microscopy and transmission electron microscopy measurements revealed that the ZnO nanorods were wrapped by a ZIF-8 shell. The pore size distribution of these ZnO@ZIF-8 nanocomposites included micropores, mesopores, and macropores. Moreover, a Brunauer–Emmett–Teller analysis showed an increase compared with the ZnO nanorods in the overall specific surface area. Due to a synergistic effect of ZnO and ZIF-8, the as-synthesized ZnO@ZIF-8 heterostructures exhibited high photocatalytic activity and completely degraded methylene blue in ∼4.5 min under solar light irradiation. Furthermore, stability experiments proved that the as-prepared ZnO@ZIF-8 nanocomposites retain over 95% of their photocatalytic activity after four cycles.