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

Highlights: • 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. -- Abstract: 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.