Covalent Organic Framework‐Amplified Polarization Loss in Ultralight Schottky Heterojunction Aerogels for Low‐Frequency Electromagnetic Wave Absorption

Abstract Constructing heterostructured materials offers a promising strategy for enhancing electromagnetic wave (EW) absorption. However, rationally designing heterostructures with dielectric‐rich interfaces to achieve low‐frequency (2–8 GHz) EW absorption remains a formidable challenge. Herein, ultralight covalent organic framework/graphene (COFG) Schottky‐heterojunction aerogels are fabricated via an in situ confined assembly strategy. By precisely tailoring the thickness and coverage of the COF nanolayer on graphene sheets, the key dielectric genes governing polarization and conduction losses are effectively regulated. Driven by built‐in electric fields and space‐charge regions at the COF‐graphene heterointerface, significant charge transfer and redistribution endow the aerogels with exceptional low‐frequency EW absorption performance. The optimized aerogel achieves a minimum reflection loss of −79.8 dB (corresponding to 99.99999895% absorption efficiency) at 6.12 GHz (C band) and a wide effective absorption bandwidth of 6.96 GHz at a thickness of 2.35 mm and a low filling content of 7 wt.%. This work pioneers the use of COFs to precisely engineer dielectric genes in Schottky‐heterojunction aerogels, establishing an innovative strategy for designing advanced lightweight absorbers targeting the critical low‐frequency spectrum.