Functionalized Co3O4 graphitic nanoparticles: A high performance electrocatalyst for the oxygen evolution reaction

We describe a novel synthesis technique for the production of graphitic carbon functionalized Co3O4 (G/Co3O4), which involves the rapid decomposition of cobalt nitrate in the presence of citric acid. Upon immobilization of the G/Co3O4 upon Screen-Printed macro-Electrodes (G/Co3O4-SPEs) the G/Co3O4-SPEs were found to exhibit remarkable electro-catalytic properties towards the Oxygen Reduction Reaction (OER). A detailed investigation has been carried out on the influence that the graphitization of the citric acid has, during the course of preparation of Co3O4, upon the ability of the G/Co3O4 to catalyse the OER within alkaline conditions (1.0 M KOH). The graphitization of citric acid ensures the uni-form distribution of Co3O4 and enhanced conductivity with maximal exposure of active sites, which are the key parameters to delivering enhanced electrochemical activity. The G/Co3O4-SPEs exhibits an overpotential of 304 mV (recorded at 10 mA cm(-2)), a Tafel slope of 110 mV dec(-1) and remain stable in its signal output (achievable current density) at varying temperatures (5-50 degrees C), and after 10 h of chronoamperometry in 1.0 M KOH. The G/Co3O4 SPE's OER activity was found to be superior to that of bulk and nano Co3O4. The results exhibited within this study will enable production of high-performance and environmentally benign electrocatalysts towards the OER for use within water splitting devices. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.