Facile synthesis and superior photocatalytic and electrocatalytic performances of porous B-doped g-C3N4 nanosheets

As a low-cost visible-light-driven metal-free catalyst, graphitic carbon nitride (g-C₃N₄) has attracted increasing attention due to its wide applications for solar energy conversion, environmental purification, and organic photosynthesis. In particular, the catalytic performance of g-C₃N₄ can be easily modulated by modifying morphology, doping, and copolymerization. Simultaneous optimization, however, has little been achieved. Herein, a facile one-pot strategy is developed to synthesize porous B-doped g-C₃N₄ nanosheets by using H₃BO₃ and urea as the precursor during thermal polymerization. The resultant B-doped g-C₃N₄ nanosheets retain the original framework of bulk g-C₃N₄, while induce prominently enhanced visible light harvesting and narrowing band gap by 0.32 eV compared to pure g-C₃N₄. Moreover, the adsorption capacity and photodegradation kinetics of methylene blue (MB) under visible light irradiation over B-doped g-C₃N₄ nanosheets can be improved by 20.5 and 17 times, respectively. The synthesized porous B-doped g-C₃N₄ nanosheets also exhibit higher activities than pure g-C₃N₄ as bifunctional electrocatalyst for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The enhanced catalyst performance of porous B-doped g-C₃N₄ nanosheets stems from the strong synergistic effect originating from the larger exposed active sites generated by the exfoliation of g-C₃N₄ into nanosheets and the porous structure, as well as the better conductivity owing to B-doping. This work provides a simple, effective, and robust method for the synthesis of g-C₃N₄-based nanomaterial with superior properties to meet the needs of various applications.