Ultrawideband Electromagnetic Wave Absorber Based on Bionic Wedge Structures

Owing to their exceptional electromagnetic attenuation capabilities and robust structural stability, porous carbon architectures have emerged as promising candidates for next-generation electromagnetic wave-absorbing materials. Although the implementation of classical gradient structural engineering enhances impedance matching in porous carbon, this approach inevitably sacrifices volumetric loss of material density. In contrast, the standard compensation strategy of increasing absorber thickness to amplify microwave dissipation capabilities creates a fundamental limitation in thickness-sensitive applications. Drawing inspiration from photosynthetic energy conversion mechanisms, a biomimetic windmill-wedge porous carbon architecture with multiscale porosity is prepared in this study through direct pyrolysis engineering of bun-derived biomass, and the structural parameters were optimized using a genetic algorithm to enhance its absorption bandwidth, establishing a sustainable paradigm for microwave attenuation material design. Demonstrating ultrabroadband microwave absorption (2–40 GHz) with reflection loss < −10 dB, this engineered porous carbon maintains tristable angle-polarization-temperature robustness, overcoming conventional performance-environmental sensitivity trade-offs in advanced electromagnetic stealth applications. The excellent electromagnetic wave absorption performance of this material is attributed to the increase in polarization loss caused by its microstructure and the gradient matching brought by its macroscopic structure. The increase in loss volume density has a scattering effect on electromagnetic waves. In addition, this material simultaneously features a compression performance of up to 1.6 MPa and a thermal conductivity of 0.122–0.168 W/(m·K) at temperatures ranging from 25 to 300 °C. This study provides a feasible pathway for environmentally friendly and high-performance multifunctional electromagnetic wave-absorbing materials.