One-pot fabrication of 2D/2D HCa₂Nb₃O₁₀/g-C₃N₄type II heterojunctions towards enhanced photocatalytic H₂evolution under visible-light irradiation

Design of 2D/2D photocatalysts with strong interfacial interactionviaabundant 2D coupling interfaces has been proved to be an efficient strategy to promote photocatalytic performance. Herein, colloidal suspensions containing HCa₂Nb₃O₁₀nanosheets (HCNO) and dicyandiamide were adopted as feed reagents, based on which 2D/2D HCa₂Nb₃O₁₀nanosheet/g-C₃N₄composites (HCNO/CN) with efficient photocatalytic activities were synthesized by a facile one-pot method. By this way, the separation process of HCa₂Nb₃O₁₀nanosheets was eliminated and the effective heterojunction formed simultaneously. The optimal visible light-driven photocatalytic H₂-evolution activity of the composite photocatalysts was 4.5 times that of pristine g-C₃N₄(CN), and the enhanced photocatalytic activities were attributed to the following aspects. On the one hand, the large 2D contact interfaces and the matched energy bands resulted in an efficient type II heterojunction and it thus could accelerate the separation and transfer of photo-generated electron-hole pairs. On the other hand, the residual tetrabutylammonium hydroxide on HCNO obviously changed the structure of g-C₃N₄by thein situpyrolysis strategy, thus enhancing the light absorption, narrowing the bandgap and enlarging the specific surface area and pore volume of g-C₃N₄. This work presents an effective and convenient route to construct 2D/2D composite photocatalysts based on layered perovskite nanosheets and/or g-C₃N₄nanosheets, by which the compositions and microstructures of the composites were optimized simultaneously during the pyrolysis process.