Reinforced Interfacial Polarization in Composited High‐Entropy‐Alloy Nanoparticles/Graphene for Efficient Microwave Absorption

Abstract High‐entropy alloys, particularly nanoparticles (HEANPs) composed of multiple magnetic elements, have shown promise as efficient agents to address electromagnetic challenges. However, their limited magnetic loss capabilities can be inadequate when confronted with dielectric loss requirements. Herein, using a carbothermal reduction strategy, a composite microwave absorber consisting of HEANPs (CoNiCuFeMnPbMgAl) and graphene sheets (HEANPs/G), in which the graphene sheets are incorporated to mitigate dielectric limitations, is synthesized. Benefiting from the natural resonance and electric dipole polarization induced by HEANPs and graphene defects respectively, an excellent reflection loss ( RL ) of less than −30 dB is achieved in all samples. Notably, both the experimental and first‐principles results indicate that the interface polarization can be reinforced by increasing the charge transfer at the interface to further improve the absorption behavior, which is attributed to the enhanced electrical resistivity caused by the composing element species gradually increasing to eight. Consequently, the optimized octonary HEANPs/G achieves an RL value of −62.30 dB (7.20 GHz, 3.13 mm) with a broad effective absorption bandwidth of 4.16 GHz. This study establishes a relationship between multiple loss behaviors and microwave absorption capabilities in high‐entropy composites, while also providing a pathway to compensate for the shortcomings of single magnetic loss materials.