Magnetically separatable CoFe2O4/BiOCl: Controllable synthesis, superior photocatalytic performance and mechanism towards decomposing RhB, NOR and Cr(VI) under visible light

Abstract

Magnetically separatable CoFe2O4/BiOCl (CFO/BOC) fibers were facilely prepared by solvothermal growth of BiOCl on hollow electrospun CoFe2O4 nanofibers in a weak reduction ethylene glycol (EG) solvent for visible light photocatalytic degradation of various contaminants. Due to the defect level resulted from the oxygen vacancies (OVs), evident visible light response and enhanced charge transfer are achieved both for the solo BiOCl spheres and nanosheets on the CoFe2O4 fibrous support. The optimum CFO/BOC synthesized at 160 °C with a precursor concentration of 50 mM shows outstanding photocatalytic activity to degrade different pollutants of Rhodamine B (RhB, 92.9%), Norfloxacin (NOR, 75.5%), and Cr(VI) (78.0%) within 2 h under visible light. The CoFe2O4 nanofibers are not pivotal for the photocatalytic process, but mainly contribute to the photocatalysis as magnetic support, ensuring the CFO/BOC no aggregation and easy collection under an external magnet. In contrast, the OVs play an important role in the visible light absorption, reactive oxygen species generation and redox process during the photocatalytic process. In detail, both photosensitization of RhB and species of h+ and·O2- contribute to the degradation of RhB, while NOR decomposition is accomplished by three species (h+,·O2-,·OH). In addition, electrons are the main reactive species for the photoreduction of Cr(VI). Compared to current reported CoFe2O4/BiOI photocatalysts, significant advances for the CFO/BOC are obtained not only for the cheap BiOCl with OVs for the photocatalytic application, but also much clearer investigation of more details of CFO/BOC photocatalysts such as light absorption, charge transfer and active species for the degradation of various pollutants.