Double heterojunction CQDs/CeO2/BaFe12O19 magnetic separation photocatalysts: Construction, structural characterization, dye and POPs removal, and the interrelationships between magnetism and photocatalysis

This novel double heterojunction carbon quantum dots (CQDs)/CeO₂/BaFe₁₂O₁₉ magnetic separation photocatalysts (CCBFOMSPs) were successfully prepared via a polyacrylamide gel method and low temperature sintering technology combined with a hydrothermal method. The CQDs components in CCBFOMSPs were identified by neutron powder diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The charge carriers could transfer and separation between the valence state components (CeO₂ and BaFe₁₂O₁₉) and CQDs facilely, inhibiting the recombination of electron-hole pairs significantly by Hall effect. The photocatalytic activity of CCBFOMSPs for the degradation of mixed dyes include methyl orange (MO), rhodamine B (RhB) and methylene blue (MB) and tetrabromobisphenol A (TBBPA) were remarkably improved by regulating the electromagnetic interaction between the BaFe₁₂O₁₉ contents and the photo-generated electrons. Capturing experiment showed that the active species of hole (h_VB⁺), hydroxyl radical (•OH) and superoxide radical (•O₂⁻) played dominant roles in mixed dyes degradation. Attractively, the effect shed new light on wide applications of the double heterojunction magnetic separation photocatalysts.