Z-Scheme Core–Shell meso-TiO2@ZnIn2S4/Ti3C2 MXene Enhances Visible Light-Driven CO2-to-CH4 Selectivity

Solar photocatalysis has long relied on the rational design of semiconductor photocatalysts. Herein, a ternary meso-TiO2@ZnIn2S4/Ti3C2 MXene photocatalyst is prepared and demonstrated with a core–shell structure accompanied by few-layered Ti3C2 Mxene on the ZnIn2S4 shell. The success of the synthesis depends on a two-step method consisting of hydrothermal and electrostatic self-assembly procedures. The ternary heterojunction exhibits a good behavior for photocatalytic CO2 reduction. A mechanism study of the photocatalytic reaction indicates that the photogenerated charges transfer in a Z-scheme pathway. Moreover, the construction of the Schottky junction between metallic Ti3C2 and TiO2@ZnIn2S4 is extremely effective for the reduction reaction. Consequently, the photocatalytic rates toward CO and CH4 production are up to 30.5 and 34.0 μmol/g within 3 h of illumination by simulated sunlight, respectively, while the CH4 selectivity reaches 52.7%. This work provides a good strategy to achieve highly efficient photocatalytic CO2 reduction.