Metal ions induced dielectric and magnetic loss in Co3O4 for electromagnetic wave absorption

Despite Co3O4 has been widely applied in electromagnetic wave (EMW) absorbers, single Co3O4 doesn't have excellent EMW absorbing performance. Modification of Co3O4 with other metal ions addition is an effective way to improve its impedance matching and EMW attenuation. Herein, CuO/Cu0.3Co2.7O4/Co3O4 and NiCo2O4/Co3O4 composites have been obtained via a facile two-stage strategy, and the influence of Cu2+ and Ni2+ on the high-frequency and low-frequency EMW absorbing performance of the composites has been investigated as well. The electromagnetic parameters of samples are regulated by adding different metal ions to achieve optimum impedance matching. Dipole polarization and magnetic resonance are the main loss mechanisms. The composite with Cu2+ and Ni2+ additions exhibits the best EMW absorption with an effective absorption bandwidth (EAB) of 10.8–18.0 GHz for 2.1 mm thickness at high-frequency and 4.5–8.5 GHz for 4.9 mm thickness at low frequencies, respectively. This work offers an effective method for preparing composite materials with multicomponent broadband absorption of oxides.