NiOOH/FeOOH Supported on Reduced Graphene Oxide Composite Electrodes for Ethanol Electrooxidation

In this work, nickel (Ni) and Ni-Fe bimetallic microparticles were electrosynthesized at reduction potentials in the range from −0.70 V to −1.20 V (50 mV s−1) by cyclic voltammetry (CV) onto graphite/paraffin electrode surface modified with nanosheets of reduced graphene oxide (RGO). Previously, the RGO was electrodeposited by CV from a suspension of 1 mg mL−1 of graphene oxide in PBS solution with pH 9.18, in the potential range from −1.50 V to 0.50 V (10 mV s−1). After electrodeposition of metals, the oxyhydroxides were formed by CV in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) with successive scans until stabilization of currents. In order to characterize the developed electrodes composites, the surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Electrochemical performance of the developed electrodes composites to ethanol electrooxidation was carried out in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) by CV. The electrodes were able to induce the electrooxidation of ethanol at a potential of 0.55 V for the electrode made of NiOOH/FeOOH and around of 0.60 V for the electrode modified with NiOOH.