𝜐 𝑅,𝑖 and 𝜐 𝑃,𝑖 , and of the electrochemical steps as reductants and oxidants (subscripts Red and Ox) with stoichiometric coefficients 𝜐 𝑅𝑒𝑑,𝑖 and 𝜐 𝑂𝑥,𝑖 , and the number of transferred electrons 𝑧 𝑘 . 𝑖 is used here as a universal numerator over the various components of a reaction. The forward (subscript 𝑓) direction in this analysis will always point towards oxidation, also known as the anodic direction, and the backward (subscript 𝑏) direction towards reduction, also referred to as the cathodic direction.