Interface engineered fabrication of Bi₄O₇/BiOCl 1D/2D p-n heterojunction for enhanced visible light driven photocatalysis

Herein, Bi₄O₇ was firstly synthesized by KBiO₃ via a one-step hydrothermal method and Bi₄O₇/BiOCl was successfully prepared by in-situ etching as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Compared with single-phase materials, Bi₄O₇/BiOCl composites revealed more efficient performance for degradation of Rhodamine B (RhB) and phenol under visible light irradiation. The apparent rate constant of RhB degradation by the composite was approximately 2.1, 2.5 and 4.9 times that of BiOCl, Bi₄O₇ and P25, respectively. The enhanced photocatalytic activity was ascribed to p-n heterojunctions at the interface of the composite, promoting the efficient transfer of photo-generated carriers. Bi₄O₇/BiOCl exhibited high stability in cycling runs, which is demonstrated by XRD patterns of fresh and recycled samples. In addition, trapping agent experiments confirmed the main active species in photodegradation reactions were holes. A possible degradation mechanism of Bi₄O₇/BiOCl composite photocatalyst was also proposed in this work, which may lay the foundation for the study of new photocatalyst of Bi₄O₇-based heterojunction.