Heterogeneous interface engineering of N–doped carbon onion nanotube chains toward prominent microwave absorption

Abstract

Synthesizing lightweight, thin–profile, and high–performance microwave absorbers has emerged as an urgent research topic. A promising strategy for carbon–based materials to achieve these attributes is to rationally construct heterostructures. Herein, 0.89–1.54 at.% nitrogen(N)–doped carbon onion nanotube chains (NCONCs) were produced by blending CONCs harvested from candle combustion with HH4Cl and subjecting them to heating at 300–400 °C for 3 h. The hinge–like NCONCs revealed numerous electron transport paths, facilitating the formation of multi–tiered conduction networks. The N–doping introduced C–N groups and interfaces into the CONCs, which yielded extensive dipole and interfacial polarization. Simultaneously, the 1.14 at.% N–doping endowed NCONC–400 with suitable conductivity, thereby ensuring excellent impedance matching. The resulting synergistic effect of impedance matching and electromagnetic wave attenuation was clearly observed. Specifically, NCONC–400 exhibited exceptional performance with a maximum effective absorption bandwidth of 4.71 GHz and a peak reflection loss of –35.47 dB at 1.4 mm. The radar cross–section reduction demonstrated by NCONC–400 composites reached 21.43 dB cm2. These impressive results prove the distinctive advantages of CONCs in tailoring performance and optimizing impedance matching, which are appealing for lightweight and efficient microwave absorbers.