The rise in electromagnetic radiation has created a dire need for the development of sheer absorbing composites with tunable dielectric and magnetic responses. With interfacial engineering in carbonaceous systems, high absorption efficiency and sheerness can be obtained in the X-band region. In this work, acid-functionalized carbon nanotube/ZnO (f-MWNT/ZnO) composites have been developed and investigated to understand the effect of functionalization on electromagnetic response. Permittivity data revealed a stronger frequency-dependent response in f-MWNT/ZnO, ascribed to polarization losses induced by oxygen-containing functional groups. Furthermore, dielectric loss and Cole–Cole plots indicated numerous Debye relaxation processes in combination with Maxwell–Wagner–Sillars polarizations. Permeability measurements signify distinct peaks for f-MWNT/ZnO attributed to exchange and natural resonance; however, the pristine carbon nanotube-derived (MWNT/ZnO) composite exhibits a weaker response. Stemming from the synergy of dielectric–magnetic interactions and improved impedance matching, the f-MWNT/ZnO composite with a thickness of 1.9 mm achieved an RL of −12.7 dB, corresponding to a ~94% absorption efficiency at 12.3 GHz. Additionally, the composite exhibited autonomous self-healing, enabling the reintegration of two separated segments at 70 °C for 40 min. The findings highlight the critical role of functionalization in tailoring interfacial characteristics and enhancing absorption performance.
Kaushik et al. (Mon,) studied this question.