Conducting polymers-NiFe2O4 coated on reduced graphene oxide sheets as electromagnetic (EM) wave absorption materials

- The RGO-CPs-NiFe2O4 composites are synthesized via a simple two-step method.
- The average diameter of NiFe2O4 particles is in the range of 5-20 nm.
- The maximum reflection loss of RGO-PANI-NiFe2O4 is −49.7 dB at 12.4 GHz.
- The maximum reflection loss of RGO-PPy-NiFe2O4 is −44.8 dB at 14.9 GHz.
- The maximum reflection loss of RGO-PEDOT-NiFe2O4 is −45.4 dB at 15.6 GHz.

In this work, conducting polymers (polyaniline, polypyrrole and poly (3,4-ethylenedioxythiophene)) and NiFe2O4 coated on Reduced Graphene Oxide Sheets were successfully fabricated by a two-step method. The structure and morphology were characterized by several analytical techniques, including XRD, XPS, Raman, TEM and VSM. The microwave-absorbing properties of the composites were measured by a vector network analyzer. TEM photographs reveal that many NiFe2O4 nanoparticles with the sizes in the range of 5-20 nm firmly attached on the surface of RGO-CPs. The ternary composites have superparamagnetic character due to the presence of NiFe2O4 nanoparticles. The electromagnetic data demonstrates that the combination of graphene with conducting polymers and NiFe2O4 nanoparticles can improve the impedance matching, the 2D-structure RGO with large specific surface area improve the dielectric loss, the presence of CPs coating layer enhances the Debye dipole and dipole polarization enhances the dielectric loss. The maximum reflection loss of RGO-PANI-NiFe2O4, RGO-PPy-NiFe2O4 and RGO-PEDOT-NiFe2O4 are −49.7 dB, −44.8 dB and −45.4 dB, the absorption bandwidths with the reflection losses below −10 dB are 5.3 GHz, 5.3 GHz and 3.7 GHz with a thickness of 2.4 mm, 1.7 mm and 2.0 mm, respectively. Such excellent microwave absorption composites could be used as a new kind of candidate for the new types of microwave absorbing materials.