Clathrate-like porous graphene/TiO2 composite with strong dielectric polarization for electromagnetic microwave absorption

Abstract

Porous carbon frameworks functionalized with multi-scale particles are an important approach in highly efficient microwave absorbent design since impedance matching and polarization/conductivity loss are well balanced. The absorbent with a versatile structure that is not easily deformed within application is still in need. In this work, open-cell porous graphene (PG) functionalized with TiO2 nanorods is synthesized by the solvothermal method, creating a high specific surface area structure. Complex electromagnetic parameters indicate that the introduction of TiO2 nanorods improves the microwave absorption (MA) performance by optimizing the impedance matching and enhancing the polarization relaxation due to the large numbers of PG@TiO2 interfaces. Polarization loss plays a dominant role in microwave attenuation. In addition, the designed clathrate-like structure is anticipated to further attenuate the MA wave by multiple reflections and scatterings. Interface polarization and dipole polarization can be identified with frequencies in Cole–Cole plotting. The optimized PG@TiO2 composite with a thickness of 1.92 mm exhibits a minimum reflection loss of −55.10 dB at 14.29 GHz with a low filler ratio of 10 wt. %. This work is heuristic in the absorbent structure design and is helpful in enhancing and identification of polarization relaxation loss.