Carbon-coated Cu nanocapsules (Cu@C NCs) with controllable graphite-like shells were designed and synthesized for applications in wireless communication, military stealth or electronic devices. A modified arc plasma method was employed to prepare the NCs, where a solid carbon source was used to provide a carbon-saturated atmosphere, resulting in the constitution of core-shell nanostructures with thickness-controllable carbon shells. Formation mechanisms were involved in the nucleation and growth, adsorption-diffusion or secondary growth process. The Cu@C NCs with thicker graphite-like shells demonstrated the enhanced oxidation resistance, thermal stability and excellent electromagnetic absorption performance ranging between 2 and 18 GHz. A mass of hetero-interfaces and defects inside them strengthened dielectric polarizations and achieved impedance matching. The Cu@C NCs exhibited a minimum reflection loss of - 38.4 dB at 4.88 GHz. Benefiting from the structurally controllable core-shell nanostructure, the Cu@C NCs would become a potential candidate material for electromagnetic wave absorption applications.
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