Polarization-direction-controlled Z-scheme photocatalytic switch in Sc2CO2/Pt S2 heterostructures: A first-principles study

Constructing van der Waals (vdW) heterostructures is the most commonly used method for separating photogenerated carriers, which can effectively improve photocatalytic water-splitting efficiency. Although many vdW heterostructure photocatalysts have been proposed, there is still a lack of effective strategies to regulate the photocatalytic reaction ability. In this work, we propose a Sc2CO2/PtS2 heterostructure that can achieve the photocatalytic switch with different polarization directions (P ↑ and P ↓). Both the P ↑ and P ↓ Sc2CO2/PtS2 heterostructures are semiconductors with type-II band-edge distribution. Remarkably, through the analysis of band arrangement and the built-in electric field, we found two completely different carrier-migration mechanisms inside the two heterostructures. The Sc2CO2/PtS2 heterostructure with P ↑ can be used as a direct Z-scheme photocatalyst, showing great application prospect for water splitting. In contrast, the P ↓ Sc2CO2/PtS2 heterostructure cannot undergo photocatalytic reactions affected by the direction of the built-in electric field. Therefore, based on Sc2CO2/PtS2 heterostructure, the "on"and "off"of photocatalysis are successfully achieved in a single material. Additionally, Gibbs free-energy calculation, high light absorption, and strain tunable band gap indicate that the Sc2CO2/PtS2 heterostructure is a promising candidate for photocatalytic applications.