Nitrogen and Phosphorus Doping-Induced Surface Chemistry and Pore Structure Regulation for Electromagnetic Wave Absorption in Porous Carbon

Introducing heteroatoms into carbon materials to tailor their electronic structures has emerged as an effective strategy for enhancing electromagnetic wave absorption (EMA) properties. However, the synergistic effect of incorporating polar functional groups and crystal defects via heteroatom doping remains underexplored. In this study, a sodium chloride templating method combined with pyrolysis was employed to systematically optimize the nitrogen–phosphorus codoping ratio and calcination temperature, thereby modulating the surface chemistry and pore architecture of porous carbon matrices. The results demonstrate that polarization loss arising from polar groups and crystal defects, along with conductive and multiple scattering losses facilitated by the porous structure, collectively contribute to an enhanced dielectric loss mechanism. Consequently, the optimized material exhibits an effective absorption bandwidth of 5.53 GHz at a thickness of only 2.0 mm. This work highlights the role of N–P codoping in tailoring surface chemistry at the atomic scale, offering a valuable design strategy for next-generation electromagnetic wave absorbing materials.