Construction of type II ZnBi2O4/g-C3N4 heterojunction photocatalysts for efficient degradation of acid red B

Ultrasonic assisted hydrothermal and calcination methods were used to prepare type II heterojunction ZnBi2O4/g-C3N4 (ZBN) photocatalysts. The crystal structures, elemental compositions, morphologies and optical properties of the prepared monomer and heterojunction photocatalysts were characterized. The photocatalytic degradation efficiency of acid red B reached 95% in 180 min under UV irradiation, which was 1.82 and 1.44 times higher than that of g-C3N4 and ZnBi2O4, respectively, and the reaction rate constants were increased from 0.004 min−1 and 0.005 min−1 to 0.015 min−1. ZBN exhibited high photocatalytic activity, and the enhancement of activity can be attributed to the construction of the type II heterostructure and reduced carrier recombination. The degradation experiments of carmine, AO7, MO, MB and RhB showed that the composite ZBN had a better degradation effect on different dyes. The results of radical trapping experiments and EPR tests showed that ˙O2− plays a crucial role in the photocatalytic degradation of acid red B. Finally, the mechanism of the photocatalytic degradation of acid red B by ZBN was investigated by combining EPR, VB-XPS and radical trapping experiments.