Nanosheet assembled hierarchical Co3O4/Co9S8 microspheres for low-frequency electromagnetic wave absorption

In this work, Co3O4/Co9S8 composite microspheres were prepared to eliminate electromagnetic wave (EMW) radiation and interference problems especially toward low-frequency EMW.The results show that with 20 wt% loading ratio of Co3O4/Co9S8 in 2.5 mm paraffin matrix, the minimum reflection loss (RLmin) can be -44.3 dB at 11.84 GHz. The analysis of EMW attenuation mechanism suggests that the outstanding EMW absorption efficiency is due to the large specific surface area and the improved impedance matching and interfacial polarizations between Co3O4 and Co9S8 components. Specially, as the loading ratio of Co3O4/Co9S8 component is 40 wt%, the sample presents optimal RLmin of -52 dB at 2.72 GHz. Apparently, the Co3O4/Co9S8 composite has better EMW absorption performance at low frequency. The excellent EMW abortion property at low frequency is attributed to the good matching between permittivity and impedance of the Co3O4/Co9S8 composite.