Carbon nanofiber coated ionic crystal architecture withconfinement effect for high-performance microwave absorption along with high-efficiency water harvesting from air.

Water is considered an effective microwave absorber due to its high transmittance and frequency-dispersive dielectric constant, yet it is challenging to form it into a stable state as an absorber. Herein, we developed a water-containing microwave absorber using chemical vapor deposition (CVD), namely, the bifunctional carbon/NaCl multi-interfaces hybrid with excellent water harvesting and microwave absorption performance. Carbon/NaCl exhibits remarkable water harvesting abilities from air, exceeding 210 % of its weight in 12 h. The development of the hydrophilic/hydrophobic heterojunction interface is responsible for this outstanding performance. Additionally, the interfacial polarization provided by carbon/NaCl, along with the dipole polarization induced by the internally captured water and defects, enhances its microwave absorption. The carbon/NaCl hybrid achieved a minimum reflection loss (RL) of -69.62 dB at 17.1 GHz with a thickness of 2.13 mm, and a maximum effective absorption bandwidth (EAB) of 6.74 GHz at a thickness of 2.5 mm. Compared with raw NaCl (RL of -24.5 dB, EAB of 3.88 GHz), the RL and EAB values of the absorber increased by approximately 2.85 and 1.74 times. These results highlight the potential for bifunctional carbon/NaCl hybrid in applications within extreme environments, presenting a promising avenue for further research and development.