Synthesis and magnetic properties of crystalline mesoporous CoFe2O4 with large specific surface area

Abstract

Based on the nanocasting strategy, highly crystalline mesoporous CoFe₂O₄ were synthesized for the first time through the pyrolysis of hybrid metal nitrates within the pores of two kinds of mesoporous silica, SBA-15 and KIT-6, respectively. The Brunauer–Emmet–Teller (BET) surface areas of the samples could be as high as 155.7 m² g⁻¹ (templated by SBA-15) and 129.4 m² g⁻¹ (templated by KIT-6). Characterization results revealed that the mesoporous structures of the templates can be negatively replicated by the crystals of CoFe₂O₄, and the probable phase formation mechanism was also proposed initially. Magnetic test showed that both samples had rather low coercivity (106.5 and 212.1 Oe, respectively) due to the presence of a prominent proportion of superparamagnetic particles. It has also been found that the impregnation steps had a great influence on the stucture and properties of the products.