Investigation on the structure and physical properties of Fe3O4/RGO nanocomposites and their photocatalytic application

Abstract

In the present work, we have investigated the structural, optical, photocatalytic activity, electrical transport and magnetic properties of Fe3O4 nanoparticles and its composite with reduced graphene oxide (Fe3O4/RGO) by varying the ratio of reduced graphene oxide (RGO: 2% and 4%). Fe3O4 nanoparticles and RGO were synthesized by the modified sol-gel and Hummers methods respectively. The as-prepared samples were examined by various analytical techniques to investigate their functional properties and possible applications. Rietveld refinement analysis of the XRD data reveals face-centered cubic (fcc) structure of the Fe3O4 nanoparticles and confirms the characteristic planes of magnetite phase. The average crystallite size of the Fe3O4, Fe3O4/RGO (2%) and Fe3O4/RGO (4%) samples was estimated using Scherrer's equation and found to be ∼10, 15 and 19 nm respectively. TEM/HRTEM micrographs establish spherical shapes of the magnetite nanoparticles with an average diameter of ∼12 nm for Fe3O4, while 17 and 20 nm in the nanocomposites respectively. The low temperature resistivity measurements exhibit semiconducting nature of all the samples and follow variable range hopping (VRH) mechanism. The magnetic measurements demonstrate typical superparamagnetic behavior of the samples at room temperature. The photocatalytic performance of the samples has been investigated for the decolorization of methylene blue (MB) organic dye under visible light irradiation. The Fe3O4/RGO nanocomposites display better adsorption behaviour and excellent photocatalytic activity than RGO and Fe3O4 nanoparticles. This may be due to strong interactions between Fe3O4 nanoparticles and graphene sheets.