Carbon Dots/CoFe2O4 Mesoporous Nanosphere Composites As a Magnetically Separable Visible Light Photocatalyst

Abstract Carbon dots (CDs)/CoFe 2 O 4 mesporous nanosphere composites were prepared. In comparison with CoFe 2 O 4 , the CDs/CoFe 2 O 4 composites exhibited the enhanced photocatalytic activity in the degradation of methylene blue (MB) in the presence of H 2 O 2 under the visible light irradiation. Specifically, the degradation rate attained using the CDs(4 wt %)/CoFe 2 O 4 composite was about 3.65 times higher than that with neat CoFe 2 O 4 . Moreover, the CoFe 2 O 4 paramagnetic nanospheres allowed facile repeatable use of CDs/CoFe 2 O 4 composites after magnetic separation. After five runs, the reduction of degradation rate was less than 5%, reflecting favorable photostability and magnetic separability of CDs/CoFe 2 O 4 composites. The CDs not only enhanced visible light utilization efficiency of CoFe 2 O 4 due to up-conversion photoluminesence, but also promoted the transfer and separation of electron-hole pairs as a result of their outstanding charge transfer characteristics, which collectively accelerate the generation of reactive species (such as • \({\text{O}}_{2}^{ - }\) , • OH, and h + ) in the presence of H 2 O 2 .