Porous graphitic carbon nitride nanosheets by pre-polymerization for enhanced photocatalysis

A facile and green method was developed to fabricate porous graphitic carbon nitride (g-C₃N₄) nanosheets by simply pre-polymerizing melamine at 350 °C for 2 h. A porous structure was formed in the resulted g-C₃N₄ (CN-350). Consequently, the specific surface area and pore volume of CN-350 was greatly enhanced, resulting in superior performance in photocatalytic hydrogen evolution and dye degradation. The hydrogen evolution rate and degradation constant of CN-350 were 11.2 and 8.8 times higher than that of bulk g-C₃N₄ under visible light irradiation. The porous structure not only provided CN-350 with abundant active catalytic sites and cross-plane diffusion channels to facilitate the charge and mass transportation, but also promoted the charge separation in the photocatalytic reaction. This work provided a promising method for mass-production of highly active and stable g-C₃N₄-based photocatalysts for environmental and energetic applications.