Enhanced separation performance of g-C3N4/Ag3PO4 heterojunction photocatalyst for efficient degradation of methylene blue and bisphenol A

Type Ⅱ g-C ₃N ₄/Ag ₃PO ₄ photocatalysts were prepared by an in situ chemical precipitation method used to investigate the photocatalytic degradation performance. In this work, the g-C ₃N ₄/Ag ₃PO ₄(1:1) composite catalyst exhibited superior photocatalytic performance for MB and BPA degradation, the degradation rate of MB reached 100 % within 80 min, and the degradation rate of BPA reached 98.5 % within 100 min, which were 1.8 and 8.7 times higher than that of g-C ₃N ₄, respectively. Its reaction rate abided by the pseudo-first-order kinetics, kinetic rate constants (κ) were 0.0626 min ⁻¹ and 0.0419 min ⁻¹, respectively. Through a series of characterizations, it was found that the intimate interface contact between g-C ₃N ₄ and Ag ₃PO ₄ formed type Ⅱ heterojunction, not only shortening photogenerated carriers transfer distance and accelerating the separation of photogenerated carriers, but also enhancing the stability and reusability of the g-C ₃N ₄/Ag ₃PO ₄ composite catalyst. Meanwhile, the h ⁺ radicals and ·O ₂ ^- radicals were main active species of photocatalytic degradation reactions by the free radical trapping experiments and ESR tests further were confirmation. A possible photocatalytic mechanism was studied by UV–vis DRS, Mott-Schottky curves, the free radical trapping experiment and ESR. This aim of this paper is to improve the efficiency of photocatalytic degradation of MB and BPA by synthesizing type Ⅱ g-C ₃N ₄/Ag ₃PO ₄ photocatalysts .