Study on surface modification of g-C3N4 photocatalyst

g-C 3 N 4 powders with different morphology and surface charged property were obtained by acidification, oxidation and exfoliation treatment of melamine. Acid treatment converts -NH 2 group in melamine into -NH 3 NO 3 group, and further oxidation reduces the existing C N H bond, promotes the formation of C N C and N (C) 3 bond in g C 3 N 4 , and ensures the formation of layered g-C 3 N 4 structure; acid treatment and exfoliation were beneficial to increase the pore volume of g-C 3 N 4 and enhance the redox ability of g-C 3 N 4 . The degradation rate of acid treated g-C 3 N 4 to Rhodamine B in visible light was 3.13 times that of untreated g-C 3 N 4 , and the degradation rate of acid treated g-C 3 N 4 to ciprofloxacin was 5.04 times that of untreated g-C 3 N 4 , further indicating that acid treated-oxidation-exfoliated treatment can improve the photocatalytic degradation effect of g-C 3 N 4 and expand the application range of g-C 3 N 4 . The layered g-C 3 N 4 with different surface charges can be selectively loaded onto the semiconductor materials with exposed active crystal surfaces, providing conditions for controllable preparation of Z-type heterojunction with enhanced redox ability. • g-C 3 N 4 powders with different redox ability and surface charges was prepared. • Acid treatment promotes the formation of CNC and N-(C) 3 bonds in g-C 3 N 4 . • Acid-oxidation-exfoliation can improve the photocatalytic degradation of g-C 3 N 4 .