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

Abstract

Carbon dots (CDs)/CoFe2O4 mesporous nanosphere composites were prepared. In comparison with CoFe2O4, the CDs/CoFe2O4 composites exhibited the enhanced photocatalytic activity in the degradation of methylene blue (MB) in the presence of H2O2 under the visible light irradiation. Specifically, the degradation rate attained using the CDs(4 wt %)/CoFe2O4 composite was about 3.65 times higher than that with neat CoFe2O4. Moreover, the CoFe2O4 paramagnetic nanospheres allowed facile repeatable use of CDs/CoFe2O4 composites after magnetic separation. After five runs, the reduction of degradation rate was less than 5%, reflecting favorable photostability and magnetic separability of CDs/CoFe2O4 composites. The CDs not only enhanced visible light utilization efficiency of CoFe2O4 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 H2O2.