Facile preparation of a ZnS/ZnO nanocomposite for robust sunlight photocatalytic H2 evolution from water

Abstract

A ZnS/ZnO nanocomposite was facilely and cost-effectively prepared for visible light photocatalytic H₂ evolution. ZnS/ZnO showed good H₂ evolution activity (187 μmol g⁻¹ h⁻¹) and stability (nearly linear H₂ production rate even after 16 h) without any co-catalyst. Furthermore, ZnS/ZnO revealed superior catalytic performance in sunlight-driven H₂ evolution (1807 μmol g⁻¹ h⁻¹). Due to the electronic hybridization of ZnO band structures with ZnS-surface-states, the band bending and surface dipole moment of ZnO could occur. Under visible-light irradiation, the electrons at the ZnO/ZnS interfaces can be excited from the bent valence band level to the conduction bend of ZnO for water reduction, while the holes trapped by ZnS-surface-states can be quenched by the sacrificial reagent (S²⁻/SO₃²⁻). The created ZnS/ZnO interfaces with ZnS-surface-states led to a lower band gap energy and enabled the visible light response.