Biomass-derived Co@crystalline carbon@carbon aerogel composite with enhanced thermal stability and strong microwave absorption performance

A novel Co@crystalline carbon@carbon aerogel composite with yolk-shell structure was fabricated via a green and facile method using biomass-based alginate aerogels as precursor. In the resultant composite, a large amount of highly crystallized Co nanoparticles (∼41.5 wt%) with a diameter of 5–20 nm was coated with crystalline carbon layer and evenly embedded in the porous carbon aerogel matrix. Due to core-shell Co@crystalline carbon structure, the thermal oxidation stability of the composite can be significantly improved. The porous composite also had the high surface area (425 cm 3  g −1 ) and showed considerable magnetization. Benefitting from the well-designed constitution and structure, the Co@crystalline carbon@carbon aerogel composite showed great microwave absorption performances. When the filler loading of the composite in wax was only 10 wt% and the thickness of the absorber was as thin as 1.5 mm, the maximum RL reached −43 dB. The excellent microwave absorption performances with low filler loading and ultrathin thickness make the aerogel composite show great potential application in the microwave absorption field.