The development of Ti₃C₂T_x MXene-based electromagnetic wave-absorbing materials faces a persistent challenge in balancing conductivity loss and polarization relaxation. To resolve this conflict, we propose an “interface engineering–human–computer interaction (HCI)” strategy to regulate the evolution of permittivity and decouple the interdependency between conductivity (σ) and relaxation time (τ). First, by integrating the Debye relaxation model and transmission line theory into Python-based interactive modules, an HCI framework is established that quantitatively guides the optimization of permittivity trends and provides feedback on intrinsic Debye-parameter variations. Guided by these theoretical optimizations, nitrogen-doped SiO₂-coated Ti₃C₂Cl_x MXene (SMX) composites were subsequently prepared via interface engineering. The insulating SiO₂ layer suppresses excessive σ while introducing heterogeneous interfaces that prolong τ. Meanwhile, the surface heterogeneous dipole generated by nitrogen doping induces a hysteresis of τ. Consequently, this theory-guided design enables the optimized SMX-S2-N1 to achieve a 5.2 GHz effective absorption bandwidth, overcoming the inherent limitation of narrow absorption bandwidth in MXene single-component materials. This study not only addresses the restricted absorption bandwidth of monolithic MXenes but also offers a mechanistic understanding of dielectric loss through Debye model analysis, bridging semiempirical design principles with theoretical frameworks.

With the development of the miniaturization of electronic equipment and lightweight weapon equipment, there are new requirements for electromagnetic wave absorption material (EMWAM). EMWAM has outstanding electromagnetic wave absorption properties and lightweight characteristics become an important direction of research. In this study, graphene/g-C₃N₄ (GGCN) EMWAM was first synthesized in situ by simple heat treatment, in which the g-C₃N₄ had a porous structure and dispersed on the surface of graphene. The impedance matching of the GGCN was well adjusted by decreasing the dielectric constant and attenuation constant due to the g-C₃N₄ semiconductor property and the graphite-like structure. The EMW loss mechanism of GGCN was also analyzed by simulating GGCN’s electric field mode distribution and resistance loss power density. The analysis result shows that the distribution of g-C₃N₄ among GGCN sheets can produce more polarization effects and relaxation effects by increasing the lamellar spacing. Furthermore, the polarization loss of GGCN could be increased successfully by porous g-C₃N₄. Ultimately, the EMW absorption property of GGCN is optimized significantly, and GGCN exhibits excellent EMW absorption performance. When the thickness is 2 mm, the effective absorption bandwidth (EAB) can reach 4.6 GHz, and when the thickness is 4.5 mm, the minimum reflection loss (RL_min) at 4.56 GHz can reach −34.69 dB. Moreover, the practical application of EMWAM was studied by radar cross-section (RCS) simulation, showing that GGCN has a good application prospect.