Enhanced electromagnetic wave absorption by optimized impedance matching: covalently bonded polyaniline nanorods over graphene nanoplates

Abstract

Absorbers based on graphene nanoplates (GNPs) are a promising and low-cost solution to electromagnetic (EM) wave pollution; however, it is well known that GNPs by themselves cannot effectively attenuate an EM wave. To elucidate the limiting factors of GNPs and their mechanism of EM wave absorption, a series of GNP-polyaniline composites (GNPs-PANI) were fabricated by growing polyaniline (PANI) nanorods in situ over GNPs with various concentrations of perchloric acid (HClO4) as a dopant. The correlation between HClO4 doping concentration and microstructures as well as conductivity were investigated. The microwave absorbing performance (MAP) was examined, and it was found that when the doping concentration of HClO4 was 1 M, the effective absorption bandwidth (i.e., the range where the reflection loss (RL) < − 10 dB) was as wide as 5.81 GHz and covered the entire X-band. By investigating the effects of impedance matching and attenuation characteristics, we were able to demonstrate that impedance matching is the limiting factor, and that it can be optimized by coating the GNPs with PANI nanorods. To facilitate practical applications, a coating of phenol–formaldehyde resin (PF) filled with GNPs-PANI (PF/GNPs-PANI) was fabricated by spraying, and the effective absorption bandwidth was 3.5 GHz (14.5–18 GHz).