Significant enhancement of photocatalytic performance by constructing porous g-C3N4 composed of nanosheets

Porous g-C 3 N 4 composed of nanosheets (p-gCN-NS) was synthesized through firstly grinding the hydrochloric acid-treated melamine with ammonium chloride (NH 4 Cl) and then calcining the mixture at 550° C for 2 h. The photocatalytic properties were determined by degrading Rhodamine B (RhB) and tetracycline (TC) aqueous solution (10 mg/L, 100 mL). Results show that the crystallinity, size and thickness of g-C 3 N 4 in p-gCN-NS reduced dramatically compared with those in g-C 3 N 4 sample synthesized without the addition of NH 4 Cl (gCN). Specific surface area of p-gCN-NS was 63.65 m 2 ·g −1 , which was 6.7 times that of gCN. After photocatalysis for 50 min, the degradation rate of RhB achieved 99.32% by p-gCN-NS (100 mg), whose reaction rate constant ( k  = 0.09317 min −1 ) was 10.6 times higher than that of gCN. p-gCN-NS also exhibited excellent photocatalytic activity for degrading colorless tetracycline aqueous solution. The significant improvement of photocatalytic performance can be credited to the reduced sized and thickness of g-C 3 N 4 , higher specific surface area and pore structure, as well as the weakened recombination rate of photogenerated electron–hole pairs in p-gCN-NS. This work provides a feasible and facile method for synthesis porous g-C 3 N 4 composed of nanosheets with excellent photocatalytic performance.