Dual function of rhodium photodeposition on ZnO/ZnS: Enhanced H₂ production and photocorrosion suppression in water

It is widely known that semiconductors such as ZnO and ZnS tend to be unstable in water-splitting photocatalysis due to self-corrosion by the photogenerated charges under prolonged light irradiation. In this work, we demonstrate that proper engineering of photodeposition of Rh species on ZnO–ZnS heterostructure (ZnO/ZnS) can enhance their photocatalytic activity and secure their stability at the same time. During the Rh photodeposition, both electrons and holes generated on the surface of ZnO/ZnS contributed to the formation of Rh⁰ metal and Rh-oxides on its surface. Our results have shown that as little as 0.02 at.% of Rh photodeposition can dramatically increase the activity and reduce self-corrosion of ZnO/ZnS during photocatalytic H₂ production from pure water. The average H₂ production rate of our optimal catalyst was 0.05 at.%. Rh-loaded ZnO/ZnS was ∼5.31 mmol⁻¹ g⁻¹ h⁻¹, reaching a maximum quantum efficiency of 22.9% at 365 nm.