Graphitic Carbon Nitride-Fe₂O₃ Nanocomposite as Ultra-Wideband Electromagnetic Microwave Absorber

It is still an urgent problem to develop multifunctional, economical, efficient, and expanding electromagnetic microwave (EMW) absorbers. Our study introduces composites derived from pyrolytic graphene-like C3N4 (g-C3N4), where Fe2O3 magnetic nanoparticles are grown in situ and exhibit excellent absorption characteristics. The g-C3N4/Fe2O3 composite boasts an ultrawide effective absorption bandwidth within the X and Ku frequency bands, where a minimum reflection loss (RLmin) of −52.4 dB and a maximum bandwidth of 10.56 GHz were achieved. Through the analysis of the Cole–Cole curve, five obvious uniform arc length relaxation peaks are observed, signifying that the dielectric loss performance is excellent, and the total polarization relaxation time is calculated to be 0.389 ns. Intriguingly, the RLmin values correspond to thicknesses consistently higher than the 1/4 wavelength criterion, implying that the composite’s superior EMW absorption capacity is due to destructive interference and the prominent polarization loss mechanism. This finding highlights the potential of the g-C3N4/Fe2O3 composite in the study of ultra-wideband EMW absorption, providing valuable insights for future researchers in this field.