KCa2Nb3O10/ZnIn2S4 nanosheet heterojunctions with improved charge separation efficiency for efficient photocatalytic CO2 reduction

•ZnIn2S4/KCa2Nb3O10 nanosheet heterojunctions are constructed by in-situ solution-processed method.•The optimal sample shows significantly enhanced photocatalytic CO2 reduction activity than bare ZnIn2S4 and KCa2Nb3O10.•The enhanced photocatalytic activity is ascribed to the improved charge separation efficiency of heterojunctions. [Display omitted] Construction of heterojunctions with face-to-face contact is an excellent strategy for highly efficient photocatalytic CO2 reduction system. Herein, ZnIn2S4/KCa2Nb3O10 (ZnIn2S4/KCNO) 2D/2D nanosheet heterojunctions are fabricated via an in-situ solution-processed method, and the optimal 20%-ZnIn2S4/KCNO heterojunction shows a significantly enhanced photocatalytic activity with the CO production rate of 4.69 μmol g−1 h−1, which is about 12.31 and 1.95 times higher than that of bare ZnIn2S4 and KCa2Nb3O10 under simulated sunlight irradiation. The as-prepared ZnIn2S4/KCNO nanosheet heterojunctions exhibit tremendously improved charge transfer and separation efficiency. The ultrathin structure KCNO is conducive to the rapid transmission of photogenerated electrons, while the nanoflower-like structure ZnIn2S4 is conducive to the full contact with the reactants to produce more protons, resulting in significantly boosted CO production performance. This work gives a new strategy to construct 2D/2D nanosheet heterojunctions for photocatalytic CO2 conversion, which can offer significant inspirations for other 2D hybrid systems.