Facile synthesis and excellent microwave absorption performance of ultra-small ZnO-doped onion-like carbon nanoparticles

Ultra-small ZnO-doped onion-like carbon (ZnO-OLC) nanoparticles (NPs) were synthesized by metal organic chemical vapour deposition, and OLC NPs were subsequently obtained by HCl treatment of the as-synthesized ZnO-OLC NPs. For the ZnO-OLC NPs, an optimal reflection loss of −58.7 dB and a wide effective bandwidth of 7.0 GHz were achieved at a very low filler weight loading ratio of 5%; superior to those of OLC NPs. Experimental results and theoretical analyzes indicated that the ZnO dopant could degrade the permittivity and polarization loss of the OLC NPs due to interaction between Zn, O and C atoms, and thus improve their impedance matching and microwave absorption performance. This work provides a new insight into how the ZnO doping affects the microwave absorption performance of OLC NPs from a theoretical point of view, and is expected to be a useful reference for the future design of related microwave absorbers.