Magnetic‐Dielectric Synergetic Strategy for Broadband Microwave Absorption via the Coupling of Flower‐Shaped Fe ₃ O ₄ and Conductive Cu/AgHT‐NH ₂

ABSTRACT Achieving broadband microwave absorption requires an optimal balance between conductive loss and magnetic loss. Here, the electrical conductivity of semiconductive MOFs (Cu/AgHT‐X, X = –NH 2 , –NO 2 , and –COOH, HT = benzenethiol) is tuned with different electrophilic substituents via a Schlenk reaction, allowing for effective magnetoelectric coupling and impedance matching, thereby enhancing microwave absorption. Compared to the –COOH and –NO 2 induced semiconductive CuHT–COOH (minimum reflection loss, RL min = −4.75 dB, 5.0 mm) and CuHT‐NO 2 (RL min = −8.19 dB, 2.8 mm), an enhancement of RL min of –NH 2 (−37.72 dB, 4.5 mm) facilitates the microwave absorption. The Fe 3 O 4 /CuHT‐NH 2 composite is prepared with coupling flower‐shaped Fe 3 O 4 nanoparticles (<2 µm) and CuHT‐NH 2 . The Fe 3 O 4 /CuHT‐NH 2 ‐50% exhibits an effective absorption bandwidth (EAB) of 4.46 GHz at 1.9 mm and a RL min of −45.73 dB at a thickness of 3.8 mm at room temperature, which is higher than that of the unadulterated CuHT‐NH 2 (EAB = 2.71 GHz). By combining the magnetic losses from Fe 3 O 4 particles with the resistance losses from Cu─S bonds, the broadband microwave absorption of the composites is enhanced. This work provides fundamental material insights for developing next‐generation materials aimed at electromagnetic pollution mitigation.