Exploration of Photocatalytic Overall Water Splitting Mechanisms in the Z-Scheme SnS2/β-As Heterostructure

The Z-scheme heterostructure photocatalysts have irreplaceable advantages over other heterostructures due to their ability to separate the spatial carriers and retain strong redox ability. In this study, we explored the SnS2/β-As (β-arsenene) van der Waals heterostructure with Z-scheme properties and suitable band edge positions as a potential photocatalyst for overall water splitting. Under appropriate conditions, the hydrogen evolution reaction (HER) barrier is much closer to 0. Based on the oxidation product criteria, the SnS2/β-As heterostructure photocatalyst may generate multiple end products, including •OH, H2O2, and O2. Moreover, we screen the optimal and most possible reaction pathway OER-III under irradiation among three underlying oxygen evolution reaction (OER) mechanisms, in which the intermediate species HOOH* acts as a bridge for subsequent reactions. The solar-to-hydrogen conversion efficiency of the heterostructure can reach 17.18%. This work provides new insights into designing superior photocatalysts for overall water splitting and recognizing the OER mechanism.