Hydrothermally synthesized graphene and Fe3O4 nanocomposites for high performance capacitive deionization

Abstract

Capacitive deionization (CDI) devices with low energy consumption and high salt removal efficiencies have attracted much attention. Recently, graphene has been proved to be one of the most promising materials for CDI electrodes. However, pristine graphene is far from desirable due to its low removal efficiency and unavoidable decays in performance. In this study, a reduced graphene oxide/Fe₃O₄ nanoparticle (RGO@Fe₃O₄) hybrid is proposed and synthesized via a hydrothermal approach for enhanced CDI. Electrochemical analysis of this nanocomposite material has revealed typical electrical double layer capacitive behaviour and an improved specific capacitance. Furthermore, the electrosorption capacity and current efficiency of RGO@Fe₃O₄ were found to be nearly two folds higher than that of RGO. This huge improvement is attributed to the hydroxylation of the Fe₃O₄ surface. In addition, the maximum electrosorption capacity predicted from the Langmuir isotherm was ∼8.33 and ∼4.63 mg g⁻¹, corresponding to the RGO@Fe₃O₄ and RGO electrode, respectively.