A facile template synthesis of phosphorus-doped graphitic carbon nitride hollow structures with high photocatalytic hydrogen production activity

Synthesis of graphitic carbon nitride (g-C₃N₄) is a simple, fast, metal-free, cost-effective with potential photocatalytic hydrogen evolution activity in solving energy crisis and environmental pollution. However, the low separation efficiency of electron-hole pairs of pure g-C₃N₄ is still limited the real applications. In this work, we synthesized a g-C₃N₄ photocatalyst with hollow porous worm-like structure morphology as well as phosphorus (P) doping through simple thermal polymerization with NaH₂PO₄·2H₂O as both P source and template. The results show that the synthesized g-C₃N₄ photocatalysts with hollow porous worm-like structure. The specific surface area of modified photocatalysts can be enlarged from 39.29 m²/g to 51.36 m²/g, and the photochemical test show that the as-prepared photocatalysts has better visible light response and more highly separation efficiency of photogeneration electron-hole than that of pristine g-C₃N₄. As expected, the photocatalytic hydrogen measurements reveal that the obtained P-doped hollow porous worm-like structured g-C₃N₄ has highly efficient activity than pure g-C₃N₄ under visible light irradiation. The photocatalytic hydrogen production capacity can reach up to 10.985 mmol/g for 5 h, which is about 7.6 times that of the pure g-C₃N₄. Finally, based on the above analysis, we further proposed a reasonable photocatalytic mechanism. This work provides an idea for synthesis of an efficient g-C₃N₄ based photocatalysts.