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

Abstract

In this paper, 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 graphite/paraffin electrodes surface. After electrodeposition of the rGO, iron and nickel were electrodeposited by CV with successive scans. And finally, the formation of ironnickel 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 -0.20 V 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.