Abstract: Graphitic carbon nitride (g-C₃N₄) has garnered significant attention due to its remarkable advantages such as lightweight, exceptional chemical stability and defect-rich surface. Nevertheless, its inadequate electrical conductivity and impedance matching hindered the practical implementation in the electromagnetic wave absorption (EMWA) field. To address these challenges, we developed a composites system of carbon spheres/g-C₃N₄ (CCN) through a supramolecular self-assembly strategy, subsequently integrated with reduced graphene oxide (RGO) via a water bath method. Systematic investigation revealed that the EMWA performance of CCN/RGO composites exhibited a distinct dependence (a trend of first increasing and then decreasing) on RGO content. Especially, when the mass ratio of RGO to CCN was 20 %, the CCN/RGO composite brought a minimum reflection loss value of -45.40 dB at 13.44 GHz and a broad effective absorbing bandwidth of 6.32 GHz at 2.19 mm. First-principles calculations based on density functional theory suggested that the constructed heterostructure effectively facilitated electron mobility and charge redistribution, boosting both conductive loss and polarization loss mechanisms. The exceptional absorption performance was ascribed to the synergistic effects of conductive loss, relaxation loss, and suitable impedance matching. As a results, this work provided a rational design strategy for high-performance g-C₃N₄-based EMWA materials.

Key words: Graphitic carbon nitride, Electromagnetic wave absorption, Conductivity, Impedance matching, Polarization loss