Ultralight multifunctional aerogels with in situ enhanced chitosan networks at micro-/macroscale for super-efficiency electromagnetic metastructure absorbers

Abstract

Concurrently achieving lightweight, multifunctionality, excellent environmental adaptability, and broadband microwave absorption represents the inevitable trend in the development of microwave absorbing materials. Herein, an ultralight, elastic, multifunctional chitosan-based aerogel enhanced by carbon nanotubes (CNTs) and carbon fibers (CF) at micro−/macroscale is reported, and its super-efficiency microwave absorption is realized by the electromagnetic metastructure absorbers (EMAs) design. The resulting CF-C/C aerogel demonstrates ultra-low shrinkage (6.3 %), low density (19.64 ± 1.06 mg/cm³), low thermal conductivity (27.43 ± 0.68 mW·m⁻¹·K⁻¹), as well as exhibits self-extinguishing properties, robust fatigue mechanical performance and good dielectric properties. In response to the challenge of low-frequency microwave absorption, laser etching technology was used to shape the CF-C/C aerogel into periodic metastructures, achieving ultra-wideband (37.9 GHz within S – Ka bands), wide-temperature range (−20–200 °C), and wide-angle (5–70° incidence angle) microwave absorption characteristics. These exceptional properties highlight the practical potential of aerogel metastructure absorbers in complex electromagnetic environment.