Dispersible graphene/FeNi-N-C heterojunctions with dipole polarization for electromagnetic absorption and heat dissipation from vapor-induced graphite exfoliation

A facile vapor-phase strategy for exfoliate graphite into high-performance bifunctional graphene heterojunctions. • Strong electromagnetic wave absorption with a minimum RL of −75.3 dB and a broad EAB of 6.08 GHz. • High in-plane thermal conductivity combined with low electrical conductivity. • Surfactant-like dispersibility in solvents, enabling the fabrication of versatile coatings and composites for practical applications. The growing integration and power density of electronics require materials that combine efficient electromagnetic wave absorption with thermal management. However, synthesizing lightweight, processable 2D materials that exhibit strong electromagnetic attenuation alongside high thermal conductivity yet electrical insulation remains a challenge. Here, we present a vapor intercalation-deposition approach of merging graphite exfoliation and metal‑nitrogen‑carbon atomic-layer growth to synthesize a graphene bonded dual-atom FeNi-N-C heterojunction. FeCl 3 in the graphite interlayer can coordinate with 2-methylimidazole and catalyze the formation of C C bonds between graphene and the FeNi-N-C layer during heating. The solution-processable heterojunction exhibits outstanding electromagnetic attenuation of a low reflection loss of −75.3 dB, a broad absorption bandwidth of 6.08 GHz at 1.75 mm, a radar cross-section reduction of 51.4 dB·m 2 . It also shows low electrical conductivity (0.775 S/cm) and high thermal conductivities (10.57 W·m −1 ·K −1 in-plane, 4.03 W·m −1 ·K −1 out-plane). Mechanistic studies demonstrate that interfacial coupling between graphene and Fe(Ni)-N 4 -C atomic layers synergistically boosts dipole polarization and dielectric loss for enhanced electromagnetic attenuation, and atomic-layer design enables the decoupling of electrical and thermal transport. This work offers a low-cost, scalable route to adaptable two-dimensional heterojunctions for integrated electromagnetic wave absorption and heat dissipation in next-generation electronics. Download: Download high-res image (489KB) Download: Download full-size image