Synthesis and characterization of Ni grafted RGO—A nanocomposite with tunable magnetic properties

Abstract

This article reports one step synthesis of Ni nanoparticles grafted reduced graphene oxide (RGO) conjugate, prepared via wet-chemical pathways where ethylene glycol (C2H6O2) is used for simultaneous reduction of metal nanoparticle and RGO. Powder X-ray diffraction studies confirm absence of impurity phases in the nanocomposite; stable attachment of ∼24 nm Ni nanoparticles after being grafted on RGO is analysed from Electron Microscopy images. Raman spectroscopic studies clearly reveal creation of single layer RGO sheets and also determine the nature of defects in RGO after incorporation of Ni nanoparticles. Soft ferromagnetic (FM) behaviour with high saturation moment (MS=0.53μB/f.u.) is confirmed from magnetization measurements. A comparative study based on magnetic properties of three more composites with different volume fractions is performed. Composite with high Ni concentration shows ferromagnetic characteristics whereas the composite with dilute Ni concentration reveals superparamagnetic (SPM) behaviour. A composite with ambient Ni concentration exhibits memory effect and another mixed phase (Ni-NiO) nanoparticle grafted RGO nanocomposite depicts exchange bias (EB) effect. Grafting of metal (Ni) nanoparticles on RGO sheets with different volume fractions introduces tunable magnetic properties along with ferromagnetism at room temperature, suitable for possible spintronic applications.