The effect of phosphate modification on the photocatalytic H2O2 production ability of g-C3N4 catalyst prepared via acid-hydrothermal post-treatment

Protonation of graphitic carbon nitride (g-C3N4) based catalyst by acid treatment is proved to benefit for its photocatalytic performance. However, acid-hydrothermal method to synthesize g-C3N4 was seldom reported. In this work, phosphate-modified g-C3N4 as efficient photocatalyst for H2O2 production was prepared via acid-hydrothermal method. XRD, N-2 adsorption, UV-Vis, FT-IR, SEM, XPS, TPD, EIS, and PL were used to characterize the obtained catalysts. Phosphate modification not only influences the morphology, structure property and optical property, but also promotes the O-2 adsorption ability, leading to the improved separation rate of electrons-holes. Phosphate modified g-C3N4 catalyst shows the H2O2 concentration of 5.4 mmol L-1, more than 13.5 times higher than that of neat g-C3N4. The possible reaction mechanism is proposed.