A sustainable construction of an efficient lightweight microwave absorber from polymeric sponge

A sustainable method is proposed to prepare carbon-sponge/CoNi composites from sponge to sponge/CoNi followed by sintering. All CoNi nanoparticles (NPs) are uniformly anchored on the carbon-sponge, and the as-prepared products are stable under ultrasound treatment, implying the CoNi NPs are grown in situ on the carbon-sponge with a strong interaction. The electromagnetic microwave absorption (EMWA) performances of the carbon-sponge/CoNi are properly adjusted by controlling the calcination temperature. The carbon-sponge/CoNi obtained at 800 degrees C (C800) displayed excellent EMWA performances; the minimum reflection loss (RLmin) was -39.7 dB, and the effective absorption bandwidth (EAB, RL <= -10 dB) was more than 5.12 GHz (>= 12.88 GHz) with a thin layer thickness of 1.5 mm. The superior EMWA performances of carbon-sponge/CoNi composites benefit from the synergistic effect of magnetic CoNi and the dielectric carbon-sponge. This work can pave a new road for designing lightweight and high-performance carbon composites from sustainable materials.