Electrochemical properties of oxygen-enriched carbon-based nanomaterials
By Meirinho, S. G.; Ferraria, A. M.; Rego, A. M. Botelho do; Fernandes, A. J. S.; Viana, A. S.; Fernandes, J. C. S.; Oliveira, M. C.
Published in Journal of Electroanalytical Chemistry
Journal of Electroanalytical Chemistry
2020
Abstract
The introduction of oxygen moieties on a carbon-based material to enhance the electrode material activity for the oxygen reduction reaction (ORR) is a most unexplored experimental approach due to the risk of reducing the electron-transport ability of the electrode material. Herein, it is shown that carbon nanomaterials generated electrochemically from graphite can simultaneously show an anomalous high content of oxygen functionalities and a high heterogeneous electron transfer rate. This study was demonstrated with a set of four samples, prepared at different galvanostatic conditions. All the samples display a non-ordered carbon network dominated by aromatic rings, an O/C ratio greater than 0.4, but different amounts of various oxygen-containing functionalities. The electron-transport properties of the obtained films were appraised by cyclic voltammetry and electrochemical impedance spectroscopy. The application of these metal-free electrode materials to the ORR in the alkaline medium has shown a direct correlation between the materials catalytic activity (potential onset, kinetic current and number of electrons transferred) and the CO amount, whereas a negative correlation was found for CO. Their excellent ability for the H2O2 reduction was also demonstrated. This work opens a new perspective on the use of highly oxidized carbon nanomaterials in electrocatalysis.