Synthesis of N-doped carbon with embedded Fe/Fe3C particles for microwave absorption

Abstract

Carbon and iron composites have drawn much attention for their unique electromagnetic properties. In addition, nitrogen doping of carbon can effectively modulate the dielectric properties of carbon. Therefore, synthesis of N-doped carbon and iron composites is an alternative method for obtaining high-efficiency microwave absorption materials. In previous studies, the synthesis process was very complicated including multistep routes. In this work, N-doped carbon with embedded Fe/Fe3C was synthesized in-situ via pyrolysis of amino phenol formaldehyde resin (APF) scattered with Fe2O3 nanoparticles (APF/Fe2O3), which was obtained through a simple hydrothermal process. During the heat-treatment process, the APF resin was converted into N-doped carbon, and simultaneously, the Fe2O3 was reduced to iron nanoparticles. Then, inevitably, the iron nanoparticles reacted with carbon to form Fe3C at the interface between the iron particles and carbon. Taking advantage of multiple heterogenous interface, the interfacial polarization relaxation could be enhanced. Therefore, the N-doped carbon with embedded Fe/Fe3C particles displays microwave absorption with a maximum reflection loss of − 70 dB. Moreover, the effective absorption bandwidth (reflection loss of less than − 10 dB) reaches 6.02 GHz at a thickness of 2.13 mm. This study not only provides composites of N-doped carbon with embedded Fe/Fe3C particles with excellent stable microwave absorption but also offers a simple method for synthesizing N-doped carbon with embedded Fe/Fe3C particles.