Multiphase High‐Entropy Carbon Sphere: Defect Engineering and Multispectral Electromagnetic Response

Abstract Due to the excellent multifunctional compatibility of high‐entropy materials (HEM), the multispectral electromagnetic (EM) response of HEM and their potential multifunctional applications have received extensive attention. Herein, a “rare‐earth fixation + high‐voltage dispersion” strategy is developed to prepare carbon fiber self‐assembled carbon spheres (CS) simultaneously loaded with carbon‐defects and multiphase high‐entropy particles featuring high‐concentration oxygen vacancies (Ov) via flash Joule‐heating within 50 ms . The phase composition can be tuned by modulating the content of rare‐earth, thereby widely adjusting the imaginary part of permittivity ɛ ″ ( ɛ ″ _max : 7.97 ‐ 42.36 ), and ultimately obtaining a wide effective absorption bandwidth close to 7.0 GHz (frequency band with reflection loss < −10 dB) leveraging the synergistic effects of multiphase interfaces, Ov and carbon defects. Additionally, the Ov‐rich high‐entropy alloys/high‐entropy oxides interface imparts sunlight responsiveness to HEM, and under the condition of “1‐sun”, the increase in photocurrent can reach 0.326 µA cm ^{− 2} . With the excellent corrosion resistance of high‐entropy CS, this study offers novel insights into the integrated design and control of multispectral EM‐responsive materials, significantly promoting the development of multifunctional EM devices suitable for harsh corrosive environments.