Wave absorption properties of $\mathrm{Co}$–$\mathrm{C}$ nanoparticles prepared by the gaseous detonation method

$\mathrm{Co}$–$\mathrm{C}$ nanoparticles are synthesized via the detonation of benzene and oxygen with cobalt(III) acetylacetonate as a precursor, and the influence of heat treatment on their physical performances is explored. The results indicate that the crystallinity and degree of graphitization of $\mathrm{Co}$–$\mathrm{C}$ nanoparticles are dramatically improved after heat treatment, and the impedance matching degree also increases significantly. The wave absorption property is enhanced by more than six times, and the minimum reflection loss is -17.5 dB at 16.98 GHz. The impedance mismatching is the main reason for the poor wave absorption of original $\mathrm{Co}$–$\mathrm{C}$ nanoparticles. The temperature plays an important role in the impedance matching degree and wave absorption performance, and a heat-treated process can be a useful way to solve impedance mismatching of $\mathrm{Co}$–$\mathrm{C}$ nanoparticles prepared by gaseous detonation.