Carbon oxidation reactions could misguide the evaluation of carbon black-based oxygen-evolution electrocatalysts.

A variety of carbon-based materials have been reported as electrocatalysts towards the oxygen evolution reaction. However, carbon oxidation during the OER was rarely considered or even neglected in most of the reports. Herein, using carbon black as a model material, we develop a method to estimate the contribution of carbon oxidation reactions (CORs) to the measured current during the OER test. It is shown that the CORs could result in significant overestimation of the OER activity of carbon black-based electrocatalysts.