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

In this work, graphite/paraffin composite electrodes with microparticles nickel (Ni) and Ni-Fe alloy anchored in reduced graphene oxide (RGO) were confection by the electrosynthesis of the microparticles at reduction potentials from -0.7V to -1.2V (v= 50 mV/s) onto RGO nanosheets, reduced by cyclic voltammetry from a solution of 1 mg/mL of GO in PBS solution with pH 9.18, in potential range from -1.5V to 0.5V (v= 10 mV/s). After electrodeposition of metals, oxyhydroxides were formed by cyclic voltammetry in an alkaline medium of 0.1 mol/L of NaOH in a potential range of -0.2V to 1.0V (v= 100 mV/s) with successive scans until stabilization of currents. The composites were investigated by scanning electron microscopy (SEM), it was observed that the Ni microparticles had spherical shapes, while the Ni-Fe alloy did not present a defined shape. In order to evaluate the electrochemical performance of the developed composite electrodes, ethanol and methanol electrooxidation was carried out in an alkaline medium of 0.1 mol/L of NaOH in a potential range of -0.2V to 1.0V (v= 50 mV/s) by cyclic voltammetry and chronoamperometry. The electrodes were able to induce the electrooxidation of ethanol at a potential of around 0.55V for the electrode constituted by the Ni-Fe alloy and around 0.6V for the electrode modified with Ni, and for methanol in a potential around 0.55V for the Ni-Fe alloy and around 0.65V for the Ni electrode. The Ni-Fe alloy electrodes showed the electrocatalysis of the alcohols in relation to Ni electrodes.