Dual transfer channels of photo-carriers in 2D/2D/2D sandwich-like ZnIn2S4/g-C3N4/Ti3C2 MXene S-scheme/Schottky heterojunction for boosting photocatalytic H2 evolution

Construction of multi-channels of photo-carrier migration in photocatalysts is favor to boost conversion efficiency of solar energy by promoting the charge separation and transfer. Herein, a ternary ZnIn2S4/g-C3N4/Ti3C2 MXene hybrid composed of S-scheme junction integrated Schottky-junction was fabricated using a simple hydrothermal approach. All the components (g-C3N4, ZnIn2S4 and Ti3C2 MXene) demonstrated two-dimensional (2D) nanosheets structure, leading to the formation of a 2D/2D/2D sandwich-like structure with intimate large interface for carrier migration. Furthermore, the photogenerated carriers on the g-C3N4 possessed dual transfer channels, including one route in S-scheme transfer mode between the g-C3N4 and ZnIn2S4 and the other route in Schottky-junction between g-C3N4 and Ti3C2 MXene. Consequently, a highly efficient carrier separation and transport was realized in the ZnIn2S4/g-C3N4/Ti3C2 MXene heterojunction. This ternary sample exhibited wide light response from 200 to 1400 nm and excellent photocatalytic H2 evolution of 2452.1 μmol·g–1·h–1, which was 200, 3, 1.5 and 1.6 times of g-C3N4, ZnIn2S4, ZnIn2S4/Ti3C2 MXene and g-C3N4/ZnIn2S4 binary composites. This work offers a paradigm for the rational construction of multi-electron pathways to regulate the charge separation and migration via the introduction of dual-junctions in catalytic system.