Plasma‐Induced Geometry Engineering in High‐Entropy Oxide Composites for Superior Electromagnetic Absorption

Abstract The dielectric and magnetic coexistence behavior of high entropy oxides (HEOs) injects infinite dynamism in promoting electromagnetic wave (EMW) absorption, but precisely constructing their regular geometries at the nanoscale remains challenging. Herein, the controlled preparation of reduced graphite oxide loaded (CoFeNiCuMn)O with various geometries by a rapid plasma process is reported. Modifying only the metal content of the precursor can effectively influence the morphology and dielectric properties of the resulting derivatives, achieving well‐matched impedance and ensuring outstanding absorption performance. The results show that the truncated octahedral HEO/RGO composite exhibits the strongest absorbing capacity, with a minimum reflection loss of −57 dB at 14.1 GHz and the corresponding effective absorption bandwidth covering 4.13 GHz. Moreover, the constitutive relationship between the multi‐element synergies of high entropy oxides and the microwave absorption characteristics is systematically explored, and the absorbing mechanism is proposed. Delayed wireless charging time and the simulated values of RCS less than −10 dBm² at the whole detection angles further demonstrate its dissipation capability in practical application scenarios. This study not only enriches the variety of lightweight and efficient absorbing materials but also guides for the new configuration design of HEOs.