Heterogeneous photo-Fenton degradation of rhodamine B dye via a high visible-light responsive Bi2WO6 and BiFeO3 heterojunction composites

A novel Bi2WO6 and BiFeO3 heterojunction composites with enhanced visible-light response ability have been successfully synthesized via a facile solvothermal route, which possessed high heterogeneous photo-Fenton for degrading rhodamine B dye. The results of characterizations suggested that the composites of Bi2WO6 and BiFeO3 not only have been synthesized, but also the heterojunction structure have been formed. It was found that the stepped construction of Bi2WO6/BiFeO3 heterojunction can minify the band gap to promote the separation and migration of the photogenerated electron–hole pairs, thus Bi2WO6/BiFeO3 exhibited better visible-light response and photocatalytic activity than that of pure Bi2WO6, degrading Rhodamine B (RhB) 98.07% within 75 min. BiFeO3 did not exhibited the visible photocatalytic activity as same as Bi2WO6, however, it was illustrated that the heterogeneous photo-Fenton reaction can be facilitated through coupling BiFeO3. Moreover, the enhanced photocatalytic activity of Bi2WO6/BiFeO3 could further promote the Fe2+/Fe3+ cycling to form an excellent photo-Fenton system. Hence, photo-Fenton system of Bi2WO6/BiFeO3 could generate more free radicals to more efficiently degrade RhB, achieving nearly 100% after 20 min of treatment.