Improved visible-light photocatalytic degradation of pollutants under the synergistic effect of BiOI/BiFeWO6 p-n heterojunction and oxygen vacancies

The construction of p-n heterojunctions has become an effective way to develop high performance photocatalysts to remove pollutants from water. Herein, the BiOI/BiFeWO6 composites abundant in oxygen vacancies (OVs) was rationally designed by combining calcination and solvothermal methods to remove different kinds of pollutants, including rhodamine B (RhB), tetracycline (TC), ciprofloxacin (CIP) and hexavalent chromium (Cr(VI)). The surface properties, structural characterizations and photocatalytic activity of BiOI/BiFeWO6 were investigated. Scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the morphology of BiOI/BiFeWO6 was BiFeWO6 nanoparticles loaded on BiOI sheet structure. The formation of BiOI/BiFeWO6 heterojunction was demonstrated by the shift of the peaks of Bi and I elements in X-ray photoelectron spec-troscopy (XPS). Moreover, the existence of OVs was confirmed by the O 1 s spectrum and electron spin resonance (ESR). By comparison with neat BiOI and BiFeWO6, the BiOI/BiFeWO6 composite showed excellent photo -catalytic properties under visible light. The strategy that the p-n heterojunction and OVs work together opens up new avenues to fabricate future high-efficiency photocatalysts.

Automated summary

The BiOI/BiFeWO6 composites with abundant oxygen vacancies were prepared by combining calcination and solvothermal methods for the removal of different pollutants in water. The morphology of BiOI/BiFeWO6 was characterized by SEM and TEM, and the heterojunction and oxygen vacancies were confirmed by XPS, O 1s spectrum and ESR. Compared with neat BiOI and BiFeWO6, the BiOI/BiFeWO6 composite exhibited excellent photocatalytic properties under visible light. The combination of p-n heterojunction and oxygen vacancies provides a new avenue for the fabrication of high-efficiency photocatalysts.