Ultralight N‐Doped Interconnected Porous Carbon From Lignin: Synergistic Structural and Doping Engineering for High‐Performance Electromagnetic Wave Absorption

ABSTRACT The development of lightweight, high‐attenuation, and broadband carbon‐based electromagnetic wave absorbers is hindered by the intrinsic trade‐off between impedance matching and dielectric dissipation. Herein, we report a facile and scalable synthesis of N‐doped lignin‐derived interconnected porous carbon (N x ‐LIPC) via hydrogen‐bond self‐assembly and subsequent pyrolysis. The synergistic integration of the interconnected porous architecture with multi‐configurational N doping substantially boosts the absorption performance. At an exceptionally low filler loading of 3 wt%, the optimized N 0.5 ‐LIPC achieves a minimum reflection loss of −48.07 dB with a thin matching thickness of 1.9 mm. This performance represents a 350% and 130% enhancement in attenuation intensity compared with the counterparts with only nitrogen doping (N 0.5 ‐LC) or only structural regulation (N 0 ‐LIPC), respectively. Furthermore, N 0.5 ‐LIPC exhibits a broad effective absorption bandwidth of 6.17 GHz at a thickness of 1.7 mm. Mechanistic studies reveal that the three‐dimensional (3D) interconnected network not only facilitates multiple internal reflections and optimizes impedance matching but also strengthens conductive and interfacial polarization losses. Critically, density functional theory calculations corroborate that N incorporation, particularly pyrrolic and pyridinic N, generates strong localized dipoles, introducing additional dipolar polarization loss. This work offers an innovative and sustainable strategy for fabricating high‐performance carbon‐based absorbers from biomass resources.