Synthesis and characterization of graphene based nickel ferrite nanocomposites
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Date
2018-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Nickel ferrite (NiFe2O4) is an electrically insulating material, whereas reduced graphene oxide (rGO) possesses electrical and thermal conductivity, mechanical strength and chemical stability. The inclusion of rGO with NiFe2O4 leads to formation of chemically stable and magnetic nanocomposites, which can conduct electricity. Graphene based magnetic nanocomposites are frequently used in supercapacitors, MRI and absorption removal of pollutants from water. Nickel ferrite nanoparticles were synthesized with an average crystallite size of ~23 nm by sol-gel auto combustion method and annealed at 500oC and 1000oC for 2 hours. Graphene oxide (GO) was synthesized by oxidation of graphite using modified Hummers method. Reduction of GO using hydrazine hydrate yields reduced graphene oxide. The rGO/NiFe2O4 nanocomposites were fabricated by mixing of NiFe2O4 nanoparticles and reduced graphene oxide into DI water followed by thermal drying. XRD, UV-Vis spectroscopy, FTIR, EDX and VSM techniques were used to characterize the nanosamples. Crystallite size and lattice parameter of nickel ferrite nanoparticles were found to increase with increase in annealing temperature. The addition of rGO induced a surprising reduction in the crystallite size of nickel ferrite nanoparticles from 65 nm to 49 nm with retaining spinel structure. The co-existence of both phases of rGO and NiFe2O4 nanoparticles in nanocomposites were confirmed by XRD, FTIR and elemental analysis. Band gap increased while saturation magnetization and magnetic moment per mole of NiFe2O4 decreased with decrease in crystallite size. The XRD and optical analysis validated the formation of GO and rGO. Band gap of rGO showed inverse proportionality with reduction time. Elemental analysis revealed that C/O atomic ratio increased from 0.70 to 6.98 after reduction of GO into rGO. Through VSM analysis, it was observed that the saturation magnetization is reduced, whereas coercivity increased by the addition of rGO into NiFe2O4 nanoparticles. The obtained results from present investigation suggest that the electrical and magnetic properties of rGO and NiFe2O4 can be tuned according to the desired applications.
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