Ternary nanocomposites of graphene@SiO2@NiO nanoflowers: synthesis and their microwave electromagnetic properties

The ternary composites of graphene@SiO2@NiO nanoflowers were fabricated by a multi-step route. Graphene oxide (GO)@SiO2 sheets were formed by a layer of silica nanosheets coated on the surface of GO. Then, GO@SiO2 sheets were introduced as substrates for the growth of NiO nanoflowers. The microwave absorption property of the ternary composites was studied in the frequency ranging from 2 to 18 GHz, and the effect of the thickness of the ternary composites on microwave absorption was also investigated. The results indicate that graphene@SiO2@NiO nanoflowers composites exhibit enhanced microwave absorption compared with graphene@SiO2. The reflection loss of graphene@SiO2@NiO nanoflowers below -10 dB is 5 GHz (from 10 to 15 GHz) and the maximum absorption is -20.5 dB at 11.3 GHz with a thickness of 3 mm.