Insight into the kinetics and mechanism of visible-light photocatalytic degradation of dyes onto the P doped mesoporous graphitic carbon nitride

In this study, Phosphorus-doped mesoporous graphitic carbon nitride (P-mpg-C3N4) was successfully prepared by a facile simple thermal method. Microstructure and chemical properties of catalyst were studied by a series of characterization methods, the results showed that the P atoms were successfully doped on the structure of graphitic carbon nitride and uniformly distributed on the whole mesoporous nanostructure. And specific surface area of P-mpg-C3N4 can reach 198.3 m2/g, which is almost 10.7 times more than that of g-C3N4 (18.6 m2/g), pore diameter of P-mpg-C3N4 is mainly distributed in 2–20 nm and the average pore size is 11.3 nm. Photocatalytic degradation performance of the catalyst for brilliant ponceau 5R (BP-5R) in solution were studied under dark and visible light irradiation. The photocatalytic activity of P-mpg-C3N4 is about 31.1 times higher compared with that of g-C3N4, and about 3.9 times and 2.4 times than that of mpg-C3N4 and P-g-C3N4, respectively. Mechanism of its enhanced photocatalytic performance was mainly attributed to the synergistic effect of P-doping and fragmented mesoporous structure, on the one hand, which can extend visible light absorption range. On the other hand, it's can also promote the separation of photo-generated electron-hole pairs and accelerate the transfer of photo-generated electrons.