Carbon aerogels with chiral dielectric heterostructures for efficient microwave absorption and photothermal conversion

Carbon nanocoils (CNCs) have emerged as promising electromagnetic wave absorbers due to their typical chiral structure which can provide an additional dissipation mechanism by inducing cross-polarization loss. However, their high conductivity often leads to impedance mismatch, making it challenging to achieve broad absorption bandwidth and strong absorption intensity. Herein, the chiral CNC aerogels are first synthesized and then the N-doped carbon/ZnO (C@ZnO) coating is uniformly anchored on the surface of the CNC skeleton. The porous aerogel structure can effectively enhance the impedance matching of CNCs. The C/ZnO coatings synthesized via an atomic layer deposition (ALD) assisted method exhibit high uniformity, significantly enhancing polarization loss capacity. By leveraging the synergistic interplay between dielectric properties and chiral structures, the C/ZnO@CNC aerogels demonstrate excellent microwave absorption performance. At an ultrathin thickness of 1.8 mm, the composite achieves a minimum reflection loss of −57.35 dB, while a maximum effective absorption bandwidth of 6.08 GHz is attained at 2.1 mm. Furthermore, the aerogels also possess strong hydrophobicity (water contact angle of up to 136.1°) and remarkable photothermal conversion efficiency (surface temperature up to 77.4 °C at 300 mW cm−2 irradiation). This study provides a rational microstructure design strategy for chiral-dielectric aerogels, achieving synergistic enhancement of microwave absorption and photothermal conversion efficiency.