Construction of BiOBr/α-Bi2O3 p-n heterojunction as a highly efficacious visible-light-induced photocatalyst for phenol removal

Abstract

The low charge separation efficiency of synthesized photocatalyst still remains the greatest barrier to enhancing photocatalytic property. Normally, the construction of p-n heterojunction is an efficacious and ideal means to resolve this problem. Herein, a series of visible-light-induced BiOBr/α-Bi2O3 p-n heterojunctions were fabricated by incorporating a parallel flow precipitation process with a in-situ transformation method. The morphological structure, optical properties and interfacial interactions of the as-fabricated photocatalysts were systematically explored, demonstrating that p-n heterojunction generated at the interface between α-Bi2O3 and BiOBr, which remarkablely improved the photocatalytic activity. The optimized BiOBr/α-Bi2O3 (SBiBr-70) exhibited the highest photoactivity towards eliminating phenol, with the removal efficiency of 92.32% ± 2.01% after visible light illumination for 60 min, and the reaction rate constant (k) was 4.44 and 3.83 times than that of sole α-Bi2O3 and BiOBr, respectively. Such enhancement mechanism could be put down to the efficacious interfacial separation and transport of photoexcited charge pairs in BiOBr/α-Bi2O3. In addition, the SBiBr-70 hybrid displayed splendid mineralization capability and catalytical stability in degrading phenol. The quenching experiments affirmed that the photoexcited h+ and ·O2− were the principal reactive species. The photodegradation pathway of phenol was also been elucidated in accordance with the identification of intermediate products.