One-pot fabrication of 2D/2D HCa2Nb3O10/g-C3N4 type II heterojunctions towards enhanced photocatalytic H2 evolution under visible-light irradiation†
Design of 2D/2D photocatalysts with strong interfacial interaction via abundant 2D coupling interfaces has been proved to be an efficient strategy to promote photocatalytic performance. Herein, colloidal suspensions containing HCa2Nb3O10 nanosheets (HCNO) and dicyandiamide were adopted as feed reagents, based on which 2D/2D HCa2Nb3O10 nanosheet/g-C3N4 composites (HCNO/CN) with efficient photocatalytic activities were synthesized by a facile one-pot method. By this way, the separation process of HCa2Nb3O10 nanosheets 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-C3N4 by the in situ pyrolysis 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-C3N4 nanosheets, by which the compositions and microstructures of the composites were optimized simultaneously during the pyrolysis process.