where 𝐺 a,𝑖 0 is the activation energy of step 𝑖 under standard conditions (1 bar pressure, pH = 0) for chemical steps, and at equilibrium potential under the standard conditions for electrochemical steps, 𝛽 𝑖 the transfer coefficient, and ∆𝐺 𝑖 the reaction Gibbs free energy. For the electrochemical steps, ∆𝐺 𝑖 shifts with potential in the following way,