Nanoporous Nitrogen-Doped Carbon Aerogels for Electromagnetic Wave Absorption

Carbon-based foam or aerogels show prominent potential as electromagnetic wave (EMW) absorption materials owing to their light weight, low density, abundant pore structure, and good electrical conductivity. In this work, a series of nitrogen-doped carbon aerogels with abundant micropore and nanosized pores, prepared based on carboxymethyl cellulose sodium (CMC) hydrogels and via freeze-drying and pyrolysis, exhibit good EMW absorption performances. Through simply adjusting the additive amount of dicyandiamide (DCD), nitrogen-doped CMC derived carbon aerogels (NCCAs) with various morphologies, pore structures, and chemical compositions are obtained. The synthesized NCCA10 and NCCA20 achieve a minimum reflection loss (RLmin) of -56.05 dB (2.8 mm) and -39.4 dB (1.7 mm) and effective absorption bandwidth (EAB) of 2.88 GHz at 2.7 mm and 4.88 GHz at 1.6 mm, respectively. The EMW absorption mechanism implies that the enhanced performance of NCCAs can be ascribed to the synergistic effect of dielectric loss, multiple reflection loss, conductive loss, and impedance adjustment. This study provides a good way to explore EMW adsorption materials with a broad bandwidth and good absorption behavior via nitrogen element doping.