Electrochemical reactions that involve the transfer of multiple electrons, such as the oxygen evolution or reduction reaction (OER/ORR), and the hydrogen evolution or oxidation reaction (HER/HOR) are essential for a wide range of energy conversion and storage applications, including fuel cells, electrolyzers, and batteries, as well as in the electroplating, water treatment, and chemical synthesis industries e.g., the chlor-alkali process. Since the transfer of multiple electrons in one elementary step is very unlikely, as discussed by Guidelli et. al. , the transfer of multiple electrons implies that multiple electrochemically active elementary steps take place sequentially. The Butler-Volmer (BV) expression that describes the kinetics of a single electron transfer reaction was developed about 100 years ago conceptually by Butler and formalized by Erdey-Grúz, Volmer, and Wick , forming the basis for the discussion of multi-step multi-electron reactions.