Polymer-bubbling for one-step synthesis of three-dimensional cobalt/carbon foams against electromagnetic pollution

Constructing three-dimensional (3D) foam-like structure in magnetic metal/carbon composites is regarded as a promising pathway to reinforce their electromagnetic (EM) functions. Herein, a nitrate assisted polymer-bubbling strategy is reported for the synthesis of Co/carbon foams, which is simply accomplished by direct pyrolyzing the mixture of polyvinylpyrrolidone (PVP) and cobalt nitrate hexahydrate (Co(NO3)(2)center dot 6H(2)O). Co(NO3)2 center dot 6H(2)O not only plays as the source of Co nanoparticles, but also accounts for the formation of 3D microstructure through releasing gas. By manipulating the weight ratio of Co(NO3)(2)center dot 6H(2)O to PVP, the chemical composition, microstructure, and EM properties of these composites can be easily regulated. When the weight ratio reaches 1.5, the resultant composite displays good microwave absorption performance, whose reflection loss intensity and effective absorption bandwidth are superior to those of many common Co/C composites. EM analysis reveals that such architecture is greatly helpful to establish cross-linked conductive networks in the wax matrix, resulting in powerful dielectric loss under low absorber loading. Meanwhile, 3D microstructure is also beneficial for multiple reflections that equal to extend the transmission path of incident EM waves. Simple synthesis strategy and desirable properties of these magnetic carbon foams may render them as the low-cost substitute of 3D graphene for the application against EM pollution. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.

Automated summary

Constructing three-dimensional foam-like structures in magnetic metal/carbon composites through a nitrate assisted polymer-bubbling strategy allows for the regulation of properties and microstructure. By manipulating the weight ratio of cobalt nitrate and polymer, the electromagnetic properties of the composites can be easily controlled to achieve superior microwave absorption performance.