Electrochemical Degradation of Multiwall Carbon Nanotubes at High Anodic Potential for Oxygen Evolution in Acidic Media

There is great interest in electrochemical water splitting for the efficient utilization of sustainable energy. As an alternative to high-priced materials, carbon offers considerable potential. However, carbon is limited as an electrode material for the oxygen evolution reaction (OER), owing to its thermodynamic instability against electrochemical oxidation. In this study, we investigated the electrochemical degradation of multiwall carbon nanotubes (MWCNTs) under the acidic OER environment. Electrochemical oxidation of MWCNTs induces structural changes and the formation of oxygen-containing functional groups on the carbon surface. As a consequence, the electrochemical and physicochemical properties of the MWCNTs are changed during electrochemical oxidation. We carried out electrochemical, microstructural, and spectroscopic analysis to investigate the degradation of MWCNTs. By changing of the electrochemical properties of MWCNTs during the oxidation process, the carbon electrode is initially activated and can then be kinetically stabilized with prolonged oxidation under the OER conditions.