Electronically asymmetric carbon nanojunctions as GHz-active polarization centers

Electronically asymmetric sp³/sp² carbon nanojunctions function as active polarization centers under gigahertz (GHz) electromagnetic fields. A three-dimensional (3D) aerogel composed of insulating nanodiamond (ND) and conductive reduced graphene oxide (rGO) is constructed to establish electronically asymmetric sp³/sp² interfaces. Frequency-dependent dielectric analysis reveals enhanced relaxation behavior and improved impedance matching, indicating a transition from conductivity-dominated response to interfacial polarization. The composite achieves a minimum reflection loss of -35.9 dB and an effective absorption bandwidth of 7.7 GHz at a thickness of 3.1 mm. Density functional theory (DFT) calculations show that electronic states near the Fermi level and the spatial distribution of frontier orbitals are markedly asymmetric across the sp³/sp² interface, providing a microscopic basis for dynamic interfacial polarization. The nanojunction network also exhibits thermal insulation behavior, indicating multi-channel energy dissipation. These findings identify electronically asymmetric carbon nanojunctions as discrete polarization centers governing high-frequency energy dissipation and offer a general design principle for interface-driven nanoelectronic functionality.