Stability Enhancement of Integrated ZnO/Zn3As2/SrTiO3 Photocatalyst for Photocatalytic Over-all water Splitting†

Abstract

Visible and infrared radiation counts about 95% of the solar energy input on the Earth. Only a few long-wavelength responded catalysts have been reported so far. In order to achieve the goal of solar hydrogen scale-up generation, it is necessary to develop a novel catalyst that can work under main visible region longer (400-700 nm) or beyond. Nevertheless, Zn3As2, as one of the potential candidates sensitive to this light region, suffers serious photo-corrosion and low stability in photocatalytic overall water-splitting reaction (OWS). In this study, a stable ZnO/Zn3As2/SrTiO3 heterojunction photocatalyst was developed, which presented a remarkable enhanced stability and could operate in 5 cycles in 15 hours without significant activity decay. By contrast, the naked Zn3As2 only presented minutes activity. The pronounced stability and activity enhancement are due to the faster charge separation of heterojunction of SrTiO3 and ZnO/Zn3As2, and protection Zn3As2 from photo-corrosion from oxygen and water oxidation by ZnO layer. This work provides insights into a new strategy to develop stable OWS photocatalysts for solar hydrogen production and energy storage.