Dually inner-porous composites with Co@C prismatic rods anchored into graphene aerogel toward superior electromagnetic wave absorbing materials

For electromagnetic wave absorbing materials, integration of excellent electromagnetic wave absorbing property in view of strong electromagnetic wave absorbing intensity and wide effective absorption bandwidth with a very low usage, and a ultralight weight into one material is still challenging. Herein, composites of Co@C@GA (CCGA: CCGA-1, CCGA-2, CCGA-3 and CCGA-4) with a dually three-dimensional (3D) and porous structure were obtained through introducing a prismatic rod shaped Co@C prepared by calcining Co-MOF-74–3D graphene aerogel (GA). At a loading of only 12 wt%, all the CCGA with a wide weight ratio of graphene oxide to Co@C (2:1, 4:3, 1:1 and 4:5) exhibit excellent electromagnetic wave absorption properties. A minimum reflection loss (RLmin) of − 70.28 dB at 12.28 GHz with the thickness of 2.913 mm for CCGA-3 and the maximum effective absorption bandwidth (EAB) of 7.12 GHz at a thickness of 2.520 mm for CCGA-4 are achieved. The low filling ratio, the high RLmin intensity, the wide EAB and the compatibility of the two components in a broad compositional range for losing electromagnetic waves are impressive. Co@C with inner-porous and prismatic rod bundles like unique morphology is confirmed to be very important and can endow CCGA with greatly enlarged interface, enhanced conductivity and proper magnetic property, leading to the effective tuning of electromagnetic property and impedance matching condition.