TiO2 protection layer and well-matched interfaces enhance the stability of Cu2ZnSnS4/CdS/TiO2 for visible light driven water splitting

Cu2ZnSnS4-Based heterostructure materials present broad spectral absorption and a high absorption coefficient in the visible region; however, their photocatalytic activity and stability are still impeded due to photochemical corrosion. In this paper, Cu2ZnSnS4/CdS/TiO2, a double-heterojunction photocatalyst fabricated with a TiO2 protection layer and well-matched interface architecture, has been prepared by a multi-step liquid phase process. The chemically inert TiO2 protective layer on the catalyst surface restrained the catalyst photocorrosion induced by formed nascent O2 and remarkably enhanced the catalyst stability during photocatalytic water splitting. Structural characterization and theoretical simulation indicated that both interfaces between Cu2ZnSnS4–CdS and CdS–TiO2 showed highly well-matched type-II alignment, which was beneficial to the separation and transfer of photoinduced charge pairs. The Cu2ZnSnS4/CdS/TiO2/Pt catalyst under visible light achieved photocatalytic water splitting and the H2 evolution rate of the catalyst reached 8.76 μmol g−1 h−1. The catalyst activity has been maintained in multi-cycle experiments without significant decay, and its stability has been confirmed by measuring the Cd2+ concentration in the catalyst dispersion using the ICP-OES method. This work can offer a new route to design more stable and efficient Cu2ZnSnS4-based heterostructure materials for solar-driven photocatalytic water splitting to produce H2.