Synthesis of reduced graphene oxide-conducting polymers-Co ₃O₄ composites and their excellent microwave absorption properties

In this work, novel ternary composites consisting of reduced graphene oxide, conducting polymers (polyaniline, polypyrrole and poly (3,4-ethylenedioxythiophene)) and Co₃O₄ nanoparticles were successfully fabricated by a three-step method. The structure and morphology of the composites were characterized by FT-IR, XRD, XPS, TEM and Raman spectroscopy. The results showed that uniform Co₃O₄ nanoparticles with a diameter in the range of 5-10 nm were distributed on the surface of reduced graphene oxide-conducting polymers (RGO-CPs). The excellent microwave absorption properties of the ternary composites mainly originated from the dipole polarization, electronic spin and charge polarization of Co ₃O₄ nanoparticles, the efficient complementarities between RGO-CPs and Co₃O₄ nanoparticles and the solid-state charge-transfer complex between RGO and CPs. The maximum reflection losses of reduced graphene oxide-polyaniline-Co₃O₄, reduced graphene oxide-polypyrrole-Co₃O₄ and reduced graphene oxide-poly (3,4-ethylenedioxythiophene)-Co₃O₄ are -44.5 dB, -43.5 dB and -46.5 dB, the absorption bandwidths with the reflection losses below -10 dB are 4.3 GHz, 6.4 GHz and 2.1 GHz with a thickness of 3.3 mm, 3.2 mm and 3.1 mm, respectively. Such excellent microwave absorption composites could be used as a new kind of candidate for the new types of microwave absorbing materials.