Preparation of flower-like CoFe2O4@graphene composites and their microwave absorbing properties

Novel flower-like CoFe2O4@graphene composites were prepared using a spray drying technique in combination with a solvothermal method, followed by calcination. Hundreds of uniform CoFe2O4 microspheres are encapsulated with gauzy graphene to form large flower-like composites. This unique structure effectively reduces agglomeration of graphene and enhances microwave absorption performances. The minimum reflection loss of as-obtained flower-like CoFe2O4@graphene composites reaches −42 dB at 12.9 GHz with a thickness of 2 mm, and the effective absorption frequency (RL < −10 dB) is 4.59 GHz from 11.2 to 15.79 GHz. Flower-like CoFe2O4@graphene composites show better microwave absorbing performance than pure CoFe2O4 microspheres. These CoFe2O4@graphene composites are promising as light weight, broad frequency bandwidth and strong absorption microwave absorbers.