Facile synthesis of ellipsoid-like MgCo₂O₄/Co₃O₄ composites for strong wideband microwave absorption application

As the high-speed advance of electronics industry, the facile synthesis of electromagnetic wave (EMW) absorbing materials with strong absorption capability, wide bandwidth, and thin thickness are urgently needed but remain challenging. Herein, hierarchical ellipsoid-like MgCo₂O₄/Co₃O₄ composites have been effectively synthesized by a facile hydrothermal method followed by calcination process. Meanwhile, by tuning the calcination temperature not only the morphology but also the crystalline structure (CoCO₃+MgCo₂(OH)₆ → MgCo₂O₄+Co₃O₄) of the samples were attained. Especially, profiting from the distinctive anisotropic structure and the synergistic effect of dielectric and magnetic loss as well as good impedance matching, the hierarchical MgCo₂O₄/Co₃O₄ composites calcined at 450 °C exhibited excellent EMW absorption property. The minimum reflection loss (RL_min) of −48.54 dB at 12.96 GHz with the thickness of 2.6 mm as well as the broad effective bandwidth (RL < −10 dB) of 5.08 GHz (from 10.58 to 15.66 GHz) could be obtained. Moreover, the broader effective bandwidth of 5.16 GHz (from 11.66 to 16.82 GHz) was achieved at the thickness of 2.3 mm. It is expected that the extremely strong EMW absorbing capability, broad bandwidth as well as thin thickness of the MgCo₂O₄/Co₃O₄ composites will make it a great potential for attractive EMW absorber.