Hierarchically periodic macroporous ZnS-ZnO alternating heterojunctions with a double Z-scheme for enhanced hydrogen evolution

Heterostructure construction, particularly concerning optimal band arrangement and efficient charge separation characteristics, is a critical factor influencing photocatalytic performance. In this study, the preparation of hierarchically periodic macroporous (HPM) architecture by pyrolytic restructuring of ZnS is demonstrated, thereby yielding a series of heterojunctions composed alternately of ZnS and ZnO. The HPM architecture effectively shortens the carrier transport distance and elevates the charge transport efficiency. The alternating bridge connections of ZnS and ZnO constrained by the HPM architecture, facilitate the presence of quantum wells under the double Z-scheme mechanism. The effective separation of photogenerated carriers is enabled by this configuration, and their recombination rates are reduced, and the redox capacity of the heterojunctions is enhanced. Through synergistic influences of quantum wells and HPM architectures, the HPM ZnS-ZnO heterojunctions showcase remarkable photocatalytic hydrogen evolution performance. This work demonstrates that quantum wells represent a powerful strategy for energy band engineering, when combined synergistically with HPM nanoarchitectures, they can significantly enhance photocatalytic performance.