AgFeO2 Nanoparticle/ZnIn2S4 Microsphere p–n Heterojunctions with Hierarchical Nanostructures for Efficient Visible-Light-Driven H2 Evolution

The main bottleneck of photocatalytic H2 evolution is the high recombination rate of photoexcited electrons and holes. Herein, a novel composite comprising p-type AgFeO2 nanoparticles loaded on the surface of n-type ZnIn2S4 microspheres was successfully synthesized via an ultrasound-assisted method. Because of the intimate interface between AgFeO2 and ZnIn2S4 and the formed internal electric field, the ZnIn2S4/AgFeO2 p–n heterojunction has more efficient separation and migration of photoexcited charge carriers, thereby significantly increasing the photocatalytic H2 evolution rate. Compared with pure ZnIn2S4, ZnIn2S4/AgFeO2-3 composite showed a 30-fold increase in H2 evolution rate (9.14 mmol h–1 g–1). Meanwhile, various characterization techniques provided powerful proof for the formation of the p–n heterojunction and the transport pathway of the charge carrier. The specific photocatalytic mechanism was discussed for the visible-light photocatalytic H2 evolution. This work offers a valuable guidance toward the design and fabricate other p–n heterojunctions having high photocatalytic performance for use in the energy and environment fields.