Preparation of NiFe2O4 nanorod–graphene composites via an ionic liquid assisted one-step hydrothermal approach and their microwave absorbing properties

Abstract

Novel NiFe2O4 nanorod–graphene composites were synthesized by a facile one-step hydrothermal process in the presence of 1-propyl-3-hexadecylimidazolium bromide ([PHeIm][Br]). The structure and morphology of as-prepared hybrid materials were characterized by FESEM, TEM, HRTEM, AFM, XRD, FTIR, XPS and Raman spectroscopy. The results showed that uniform NiFe2O4 nanorods with a typical length of about 400 nm and a diameter of about 50 nm were well distributed on graphene sheets. The magnetic and electromagnetic parameters were measured using a vibrating sample magnetometer and a vector network analyzer, respectively. The obtained composites exhibited a saturation magnetization of 22.5 emu g−1 and a coercivity of 48.67 Oe at room temperature. A minimum reflection loss of −29.2 dB was observed at 16.1 GHz with a thickness of 2.0 mm, and the effective absorption frequency (RL < −10 dB) ranged from 13.6 to 18 GHz, indicating the excellent microwave absorption performance of the novel composites in the range of 13.6–18 GHz. The absorbing performance of the NiFe2O4 nanorod–graphene composites was better than that of the NiFe2O4 nanoparticle–graphene composites.