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 H-2 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 H-2 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.