Synthesis and excellent electromagnetic absorption properties of polypyrrole-reduced graphene oxide–Co3O4 nanocomposites

•PPy-RGO-Co3O4 nanocomposites were firstly synthesized by a three-step method.•The size of Co3O4 nanoparticles is in the range of 10-30 nm.•The maximum RL of PPy-RGO-Co3O4 is −33.5 dB at 15.8 GHz at a thickness of 2.5 mm.•The absorption bandwidth of PPy-RGO-Co3O4 with RL below −10 dB is up to 11.4 GHz.

A novel kind of polypyrrole-reduced graphene oxide–Co3O4 (PPy–RGO–Co3O4) nanocomposites was firstly synthesized by a three-step method. The results indicate that small Co3O4 nanoparticles with the sizes in the range of 10–30 nm are anchored on the surface of PPy-RGO. The results demonstrate that the maximum reflection loss of PPy–RGO–Co3O4 is −33.5 dB at 15.8 GHz with a thickness of 2.5 mm and the absorption bandwidth with the reflection loss below −10 dB is up to 11.4 GHz (from 6.6 to 18.0 GHz) with a thickness in the range of 2–4 mm, suggesting that the microwave absorption properties and the absorption bandwidth are obviously enhanced by adding Co3O4 nanoparticles. Such strong microwave absorption materials could be used as a kind of candidate for the new types of microwave absorbing materials.