Electrocatalysis of Ethanol and Methanol Electrooxidation by Composite Electrodes with NiOOH/FeOOH Supported on Reduced Graphene Oxide onto Composite Electrodes

Abstract

This paper presents graphite/paraffin composite electrodes modified with microparticles of nickel (Ni) and Ni-Fe alloy anchored in reduced graphene oxide (rGO); these electrodes were made by electrosynthesis. Firstly, the electrodeposition of reduced graphene oxide was made by cyclic voltammetry (CV) onto the graphite/paraffin electrodes’ surface. After electrodeposition of the rGO, iron and nickel were electrodeposited by CV with successive scans. Finally, the formation of iron-nickel oxyhydroxide on the electrode surface was performed by cyclic voltammetry in alkaline medium. The composites were investigated by field emission gun scanning electron microscopy (FEG-SEM); it was observed that the Ni microparticles had spherical shapes, while the Ni-Fe alloy did not present a defined shape. The composite electrodes were used to analysis ethanol and methanol electrooxidation in an alkaline medium of 0.10 mol L−1 of NaOH in a potential range of from −0.20 to 1.0 V (vs. Ag/AgCl) at 50 mV s−1 by CV. The electrodes were able to make the electrooxidation of ethanol at a potential of around 0.57 V for the electrode constituted by the Ni-Fe alloy and around 0.61 V for the electrode modified with Ni, and for methanol in a potential around 0.57 V for the Ni-Fe alloy and around 0.66 V for the Ni electrode. The Ni-Fe alloy electrodes showed the electrocatalysis of the alcohols in relation to Ni electrodes.