How reliable are the overpotentials reported in energy conversion electrocatalysis?

Abstract

Redox reactions of small molecules catalyzed electrochemically by more energy efficient materials are the future of sustainable energy conversion and storage. When these reactions are an electrocatalytic process, the markers used to determine activity are always expressed as a function of applied electrochemical potential and this can be expressed in more than one form and against more than one reference electrode. However, to make a rational comparison between different studies, converting this potential to the reversible hydrogen electrode (RHE) scale is the commonly followed practice. This perspective article teaches the basics of the idea of representing activity and other markers of electrocatalysts used in various energy conversion and storage reactions and the need for converting them all to the RHE scale. While most researchers are well aware of this need for conversion, a lack of awareness about the unintentional errors made during the conversion of potential to the RHE scale is truly concerning as the errors may exceed more than 140 mV in some cases if the source of error is not taken into account. Hence, this article is dedicated to discussing the sources of error and their influence on results while also providing remedial actions to avoid them by giving best practices.