Folded nano-porous graphene-like carbon nitride with significantly improved visible-light photocatalytic activity for dye degradation

Graphitic carbon nitride (g-C3N4) prepared by traditional methods has various disadvantages, e.g., small specific surface area, low band gap, high photo-generated carriers recombination and low exfoliation efficiency, which limits its practical application. In this study, folded nano-porous graphene-like g-C3N4 (abbreviated as FNPGLCN) was prepared by a simple but quite effective method of calcining urea in water. The effects of calcination temperature on crystal structure, energy band and microstructure of g-C3N4 were investigated. The photocatalytic activity for methylene blue (MB) degradation under visible-light was evaluated. The results revealed that the FNPGLCN had higher specific surface area (197 m(2)/g) and larger band gap (2.87 eV) than bulk g-C3N4. With calcination temperature rising from 450 to 500 degrees C, the pore size and specific surface area of FNPGLCN increased. However, the pore structure almost disappeared and the thickness of g-C3N4 became thinner at 550 degrees C. Compared with bulk g-C3N4, the photocatalytic degradation rate of FNPGLCN for MB increased from 0.131 to 1.298 h(-1). The significant enhancement of visible photocatalytic activity was mainly attributed to folded nano-porous structure, which simultaneously improved visible-light absorption range and strength, and enlarged the band gap and specific surface area of g-C3N4.