Heteroepitaxial growth of core-shell ZnO/CdS heterostructure for efficient and stable photocatalytic hydrogen generation

Abstract

Solar-driven water splitting provides a promising way to generate clean and renewable hydrogen. The efficiency and stability are of importance for practical application of this technology. Herein, colloidal ZnO/CdS heterostructure catalysts were obtained via a two-step heteroepitaxial growth strategy. It was discovered that the anion exchange step plays an important role in construction of core-shell ZnO/CdS heterostructure and photo-induced electron-hole separation is promoted by reducing the charge carriers transfer distance in prepared ultra-small heterostructure. By optimizing the molar ratio of the ZnO and CdS components, the highest hydrogen generation rate of 669.6 μmol/h (100 mg) was achieved without any cocatalyst loading in the presence of S2− and SO32− as sacrificial reagents. Furthermore, the heterostructure displayed excellent photocatalytic stability for ∼72 h. The photocatalytic performance of as-prepared nanoscale ZnO/CdS is superior than that of the well-studied bulk ZnO/CdS heterostructures, demonstrating its great potential in practical application of photocatalytic water splitting.