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Electrocatalysis of Ethanol and Methanol Electrooxidation by Composite Electrodes with NiOOH/FeOOH Supported on Reduced Graphene Oxide onto Composite Electrodes
* 1, 2 , 3, 4 , 5
1  Engineering of Energy, Campus of Rosana, São Paulo State University (UNESP), 192740-000 Rosana, São Paulo, Brazil.
2  Sensors and Biosensors Group, Department of Chemistry, Universitat Autònoma de Barcelona, Edifici Cn, 08193 Bellaterra, Barcelona, Spain.
3  Department of Physics and Materials Science, University of São Paulo, 13566-590 São Carlos, São Paulo, Brazil.
4  CEFITEC, Physics Department, Faculty of Science and Technology, Universidade Nova de Lisboa, Campus de Caparica, 2829-516, Caparica, Portugal.
5  Engineering of Energy, Campus of Rosana, São Paulo State University (UNESP), 192740-000 Rosana, São Paulo, Brazil;

Abstract:

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.

Keywords: Composite; RGO; Oxyhydroxide; Ethanol; Methanol; Electrocatalysis
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