Three-dimensional macroassembly of hybrid C@CoFe nanoparticles/reduced graphene oxide nanosheets towards multifunctional foam

Many efforts have been focused on developing the three-dimensional (3D) foams with enhanced absorption performance, improved mechanical behavior and excellent environmental stability. 3D graphene (or reduced graphene oxide) architecture with interconnected conductive network and ultralow density make it the most promising candidate for high-performance microwave absorption application. Unfortunately, they are extremely delicate to handle for the weak van der Waals interactions between neighboring nanosheets. Here, we show a simple approach via three-dimensional macroassembly of hybrid C@CoFe nanoparticles (NPs)/reduced graphene oxide (rGO) nanosheets to fabricate multifunctional foam. Firstly, hybrid hydrogels by in situ sol-gel polymerization form directly in the framework of GO aerogel. And decomposition of metal-citric acid complexes occurs during the heat treatment and formation of metal oxides is followed. RF-derived (RF-resorcinol-formaldehyde) rich carbon source can reduce CoFe2O4 to CoFe alloy via thermal treatment. Such hybrid magnetic carbon spheres not only can absorb electromagnetic (EM) wave, but also act as fillers to support stresses transferred from the reduced graphene oxide nanosheets. The compression modulus of C@CoFe/rGO (CCR) foam can reach 26 MPa. Three-Dimensional macroassembly of C@CoFe NPs/rGO nanosheets generates efficient channels for multiple reflections and scatterings in the framework, which is advantageous for electromagnetic attenuation. (C) 2019 Published by Elsevier Ltd.