Efficient electromagnetic wave absorption and Joule heating via ultra-light carbon composite aerogels derived from bimetal-organic frameworks

Lightweight carbon-based aerogels with fast heat dissipation capability are promising electromagnetic wave absorber materials for developing integrated electronics, artificial intelligence, and human-interaction equipment under harsh thermal environments. Herein, the bimetallic (cobalt (Co) and nickel (Ni)) metal–organic frameworks (CoNi-MOFs), cellulose nanofibrils (CNFs), and aramid nanofibers (ANFs) were assembled into a conductive and magnetic CoNi@carbon/ANF/CNF carbon composite aerogel (CoNi@C/ACA) with an ultra-low density of 6.15 mg/cm³ using freeze-drying and subsequent carbonization treatment. Owing to the synergistic effects of multiple reflections inside the three-dimensional interconnected structures, abundant interfacial/dipolar polarizations, and coordinated dielectric and magnetic losses, the CoNi@C/ACA achieved a fascinating minimum reflection loss value of −66.57 dB and broad effective absorption bandwidth up to 6.3 GHz, which were characterized with an ultra-low loading of 1.8 wt%. In addition, it displayed good thermal stability with a super-fast Joule heating (cooling) rate at low driving voltages. These unique characteristics of the ultra-light CoNi@C/ACA make it a promising material for demanding applications, e.g., electromagnetic pollution elimination and thermal management.