Modulated band structure in 2D/2D ZnIn2S4/B-C3N4 S-scheme heterojunction for photocatalytic hydrogen evolution

Modification of photocatalysts through band structure design and defect engineering holds significant importance to a remarkable hydrogen evolution activity. Herein, a 2D/2D S-scheme heterojunction photocatalyst (ZnIn2S4/B-C3N4) with nitrogen vacancy was rationally designed and fabricated for hydrogen evolution. Strong electrostatic interactions between negatively charged ZnIn2S4 nanosheets and positively charged B-C3N4 nanosheets resulted in the formation of 2D/2D intimate contact interfaces, which facilitate the rapid separation and transfer of carriers. By effectively doping g-C3N4 with B at various temperatures, not only the N vacancy was introduced, but also the controllable adjustment of g-C3N4 bandgap was achieved, which promotes the construction of ZnIn2S4/B-C3N4 S-scheme heterojunction. The resulting photocatalysts exhibited enhanced hydrogen evolution performance under visible light. Specifically, the optimized ZIS/BCN-450 sample demonstrated a hydrogen production rate of up to 0.876 mmol g−1 h−1, which is approximately 4.25 times that of ZnIn2S4 (0.206 mmol g−1 h−1). The significantly enhanced performances could be ascribed to the formation of 2D/2D S-scheme heterojunctions, which effectively promote interfacial photogenerated charges separation and transfer. In addition, recycling experiments revealed that the catalyst was highly stable. Finally, the photocatalytic mechanism for this composite was proposed and studied systematically. This research provides an innovative perspective for the development of novel photocatalysts.