Green Approach To Prepare Graphene-Based Composites with High Microwave Absorption Capacity

Chemically reduced graphene (CR-G)/poly(ethylene oxide) (PEO) composites are prepared by a simple aqueous mixing method. Graphite oxide (GO) is prepared by a modified Hummers method and further dispersed in water to form graphene oxide (G-O). The as prepared G-O is mixed with PEO and in situ reduced by L-ascorbic acid. CR-G monolayers are similar to 1 nm in thickness and similar to 1.5 mu m in both length and width as confirmed by AFM, indicating their large aspect ratio of about 1500. G-O is dispersed in PEO at the molecular level due to hydrogen bonding, and PEO acts as a barrier for CR-G layers to prevent agglomeration during the process of reduction. CR-G/PEO composites have high permittivity, resulting from the uniform dispersion of electrically conductive CR-G with high aspect ratio. CRG/PEO composite (2.6 vol %) shows high microwave absorbing capacity as its minimum reflection loss is -38.8 dB. CR-G sheets form a huge number of electrical pathways which can dissipate microwave energy into heat effectively as well as dielectric relaxation and interface scattering induced by large CR-G/PEO interfaces.