Broadband microwave-absorbing and energy-storing composite foam with pomegranate-like microstructure created from Pickering emulsion method

Rational design and construction on the microstructure of multifunctional microwave absorbing materials are significant strategy for upgrading their performances. Here, multifunctional hybrid foam with pomegranate-like microstructure are fabricated, which based on paraffin wax (PW)-in-water Pickering emulsion stabilized by cellulose nanofibrils (CNF). The in-situ polymerization of pyrrole monomer induced the creation of CNF/Fe 3 O 4 /PW/polypyrrole (PPy) hybrid foam, wherein PW microspheres were covered with CNF/Fe 3 O 4 /PPy nanocomposite shells. The obtained foam exhibited excellent microwave absorption performance with a reflection value (RL) of −55.6 dB and broadband bandwidth of 10.0 GHz (8.0–18.0 GHz). Owing to the specificity in the structure of hybrid foams with embedded PW microspheres, the maicrowave performance can be adjusted by regulating the amount of PW microspheres in composite foam. Moreover, pomegranate-like microwave-absorbing foams also show excellent photo-thermal conversion and energy storage, meaning this multifunctional composite foam has potential applications in microwave absorption, thermal energy storage systems, and smart buildings.