Nitrogen Configuration‐Driven Modulation of Built‐in Electric Field Toward Synchronously Boosted Anti‐Corrosion and Electromagnetic Wave Absorption

Built‐in electric field (BIEF) engineering has emerged as a promising strategy for regulating interface electron structure and tailoring multifunctional performance; however, constructing strong BIEF to achieve multifunctionality remains a challenge. Herein, an intensified‐BIEF strategy through nitrogen configuration regulation is proposed in CoNi/Mo 2 C@N‐doped carbon (NC) composites to simultaneously enhance electromagnetic wave (EMW) absorption and anti‐corrosion. By tailoring pyrolysis temperature, the nitrogen configuration and electronic structure of the NC matrix are systematically regulated, enlarging the work function difference and strengthening BIEF at the CoNi/NC and NC/Mo 2 C heterointerfaces. The intensified BIEF induces directional charge migration, generating oriented interface dipole arrays that enhance the dipole‐array polarization relaxation and boost conductive loss. Meanwhile, the strong BIEF facilitates electron accumulation at the CoNi surface, suppressing charge delocalization that inhibits anodic dissolution and promotes passivation. The optimized CoNi/Mo 2 C@NC achieves an effective absorption bandwidth of 6 GHz at a thickness of 1.8 mm. Meanwhile, compared with commercial absorbers, the corrosion potential is increased by 94.9%, while the corrosion current is reduced by 74.5%, demonstrating exceptional durability and ultralow corrosion kinetics in marine environments. This work reveals the mechanistic role of strong BIEF in simultaneously optimizing EMW absorption and anti‐corrosion, and provides a novel strategy for designing multifunctional materials.