Nanoparticle heterojunctions in ZnS–ZnO hybrid nanowires for visible-light-driven photocatalytic hydrogen generation

We report one-step hydrothermal preparation of ZnS–ZnO hybrid nanowires consisting of well-distributed nanoparticle-heterojunctions that induce high activity for visible-light-driven H2 evolution even without any noble metal co-catalysts. During the growth process, the nanoparticulated ZnS nanowires formed first, followed by ZnO nanocrystal growth with intercalation inside the ZnS nanowires. This growth mode could result in enriched ZnS-surface-states on the ZnO nanocrystal surfaces, as evidenced by the weakened absorption features and quenched band gap emission of ZnO in the ZnS–ZnO hybrid nanowires. Further studies by varying the ZnS to ZnO ratio in the ZnS–ZnO hybrids also proved that the population of ZnS-surface-states is crucial to the visible-light activity for photocatalytic H2 evolution. This work provides a meaningful way to develop heterostructured composites as visible-light-active photocatalysts by using wide band gap semiconductors for solar fuel production.