Facile preparation and excellent microwave absorption properties of an RGO/Co0.33Ni0.67 lightweight absorber

Abstract

Novel microwave absorbers combining Co_0.33Ni_0.67 alloy and reduced graphene oxide (RGO) are fabricated and their excellent microwave absorption properties demonstrated. Co_0.33Ni_0.67 alloy particles are prepared by a one-pot solvent-thermal method from CoCl₂·6H₂O and NiCl₂·6H₂O. The prepared Co_0.33Ni_0.67 alloy particles are confirmed from SEM observation, EDS analysis and XRD measurements. RGO/Co_0.33Ni_0.67 composites are then fabricated by adding the Co_0.33Ni_0.67 alloy particles into a colloidal dispersion of GO and thermally reducing at 210 °C. The composition of RGO/Co_0.33Ni_0.67 is characterized by Raman, XPS, VSM, XRD and FTIR measurements. An SEM micrograph indicates the sandwich-like structure of RGO/Co_0.33Ni_0.67 with Co_0.33Ni_0.67 alloy particles intercalated into the RGO sheets. By suitably adjusting the dielectric loss and magnetic loss derived from different contents of the RGO and Co_0.33Ni_0.67, an RGO/Co_0.33Ni_0.67 composite with excellent microwave absorption properties is obtained. The maximum reflection loss is up to −50 dB at a thickness of only 1.8 mm. In addition, the absorption bandwidth exceeding −10 dB reaches up to 14.0 GHz with matching thicknesses of 5.0–1.4 mm and covers the whole Ku band at a thickness of only 2.0 mm.