Boosting Photocatalytic Overall Water Splitting on Direct Z-Scheme BiOBr/ZnIn₂S₄ Heterostructure by Atomic-Level Interfacial Charge Transport Modulation

It is charming to develop direct Z-scheme heterostructure catalysts for efficiently boosting photocatalytic overall water splitting, but it is challenging for the interface to realize tight connection at the atomic level. Herein, a BiOBr/ZnIn2S4 direct Z-scheme heterostructure with a Bi–S bonded interface is designed and constructed by in situ growing ZnIn2S4 nanosheets on BiOBr nanosheets. The BiOBr subtrates extremely inhibit the aggregation of ZnIn2S4 nanosheets and enhance their stability. The designed BiOBr/ZnIn2S4 direct Z-scheme heterojunctions thermodynamically favor photocatalytic overall water splitting for simultaneous H2 and O2 production owing to their suitable band edge levels. Direct Z-scheme heterostructure and atomic-level interface connection synergistically promote the photogenerated carrier separation and transfer. As a result, the optimized BiOBr/ZnIn2S4 hybrid structure exhibits extraordinary photocalytic activity and superior cycling stability in the absence of any sacrificial agents. It achieves photocatalytic H2 and O2 production rates up to 628 and 304 μmol g–1 h–1 under sunlight irradiation, with 11.6-fold and 12.9-fold improvement compared to pristine ZnIn2S4 and BiOBr, respectively. Furthermore, the excellent photocalytic activity can remain unchanged for 24 h. This interfacial modulation will guide further developments to fabricating direct Z-scheme heterostructure.