Regulating conduction and polarization losses by adjusting bonded N in N-doped Cu/CuO/C composites.

[Display omitted] • A layer-stacked N-doped Cu/C composite with tunable microstructure was prepared. • A strategy to balance the regulation of conduction loss and polarization loss is proposed. • Its showed RL min value of −39.0 dB and the widest effective bandwidth of 5.5 GHz when the thickness is 1.56 mm. • The enhanced electromagnetic wave absorption mechanism was investigated in detail. Conduction and polarization losses are the main forms of dielectric loss, and regulating these mechanisms is key to obtaining favorable electromagnetic wave absorption performance. In this study, the conversion of graphite N and pyridine N in Cu-based metal–organic framework (MOF)-derived composites was adopted to modulate conduction and polarization losses by tuning the pyrolysis temperature and Cu salt concentration. The results show that increasing the pyrolysis temperature facilitates the conversion of pyridine N to graphite N, which is beneficial for conduction loss. Moreover, increasing the Cu concentration promotes the transformation of pyridine N to graphite N as well as, and then promotes the reverse conversion of graphite N to pyridine N, which is conducive to defect-induced polarization. The unique layered Cu/CuO/C composite obtained at 700 °C with a moderate Cu content exhibited the optimal performance with an effective absorption bandwidth of 5.5 GHz (11.6 ∼ 17.1 GHz) at an ultra-thin thickness of 1.56 mm. This is owed to its favorable impedance matching, significant conduction loss, and polarization loss (defect-induced polarization and interfacial polarization). This study provides a novel strategy for regulating conduction and polarization losses. [ABSTRACT FROM AUTHOR]