Visible Light Photocatalysis: Efficient S-Scheme γ-Bi2O3/BiOBr Photocatalyst for Phenol Degradation

Abstract

The development of heterostructures with stabilized heterogeneous structures is crucial for the improvement of photocatalytic activity and practical applications. In this study, a S-type heterojunction of γ-Bi₂O₃/BiOBr was synthesized by a simple hydrothermal method. Under simulated sunlight, the degradation ratio of phenol can attain nearly 91.75% for 17%-γ-Bi₂O₃/BiOBr heterojunction after 120 min, while only 2.8% and 52.86% for pure γ-Bi₂O₃ and BiOBr, respectively. Meanwhile, its first-order reaction rate is 3.46 and 22.81 times more than those of pure BiOBr and γ-Bi₂O₃, respectively. In addition, the 17%-γ-Bi₂O₃/BiOBr heterojunction exhibits the excellent cycle stability, as its phenol degradation ratio can retain nearly 86% after five cycle experiments. The heterojunction was analyzed as an S-type heterojunction based on XPS, EPR and free radical trapping experiments. The performance enhancement of the catalyst is thus due to the formation of an S-type heterojunction, which reduces the recombination rate of photogenerated electrons and photogenerated holes and promotes the formation of active species, thus dramatically increasing the efficiency of photocatalytic degradation of phenol.