Stability enhancement of an integrated ZnO/Zn3As2/SrTiO3 photocatalyst for photocatalytic overall water splitting†

Visible and infrared radiation account for approximately 95% of the solar energy input to the Earth. However, only a few long-wavelength responding catalysts have been reported thus far. In order to achieve the goal of solar hydrogen scale-up generation, it is essential to develop a novel catalyst that can work in the main visible region (400–700 nm) or beyond. Zn₃As₂, a potential candidate that is sensitive to this light region, suffers from serious photo-corrosion and low stability in photocatalytic overall water-splitting (OWS) reactions. In this study, a stable ZnO/Zn₃As₂/SrTiO₃ heterojunction photocatalyst was developed, which exhibited remarkably enhanced stability and operated for over 5 cycles in 15 hours without significant activity decay. In contrast, the naked Zn₃As₂ only presented a few minutes of activity. The pronounced stability and activity enhancement were due to the faster charge separation facilitated by the heterojunction of SrTiO₃ and ZnO/Zn₃As₂ and the protection of Zn₃As₂ from photo-corrosion from oxygen and water oxidation by the ZnO layer. This work provides valuable insights into a new strategy for developing stable OWS photocatalysts for solar hydrogen production and energy storage.