Decoration of Reduced Graphene Oxide with Magnesium Oxide during Reflux Reaction and Assessment of Its Antioxidant Properties

The aim of this work is the reduction and decoration of graphene oxide (GO) with magnesium oxide (MgO). In this work, GO was synthesized using modified Hummers’ protocol with (1:2), (1:3) and (1:4) graphite:potassium permanganate mass ratios. Subsequently, all GO samples (GO1:2, GO1:3, GO1:4) were reduced and decorated with magnesium oxide nanoparticles using a reflux technique at 100 °C for 2 h. Sample characterization using X-ray diffraction (XRD) reveals the presence of peaks relative to two different magnesium (Mg) phases: magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)₂). The presence of these spectral features, although characterized by a remarkable broadening, confirms the successful synthesis of Mg(OH)₂-rGO-MgO nanocomposites. X-ray photoelectron spectroscopy (XPS) spectra indicate the presence of peaks assigned to C, O and Mg. The analysis of the high-resolution XPS spectra of these elements confirms once again the presence of Mg(OH)₂-rGO-MgO compounds. The low temperature synthesis of Mg(OH)₂-rGO-MgO nanocomposite exhibiting superior catalytic properties compared to MgO–rGO nanoparticles is an important step forward with respect to the current state of the art. The antioxidant activity of six nanocomposites, namely GO1:2, GO1:3, GO1:4, MgO–rGO1:2, MgO–rGO1:3 and MgO–rGO1:4, was determined using standard protocols based on a DPPH radicals scavenging assay, an H₂O₂ scavenging assay, and a phosphomolybdate assay. All our samples exhibited dose-dependent antioxidant activity. Interestingly, among the different synthesized nanoparticles, GO1:4 and MgO–rGO1:4 showed the best performances.