In order to understand the redox properties of the latter set of compounds, their mechanisms of reduction reactions can be described by ET, proton transfer (PT), and proton coupled electron transfer (PCET) in the homogeneous solution phase, 61,62 independent of the electrode interactions. As there are no physical electrodes and explicit solvents in this approach, thus, one must assess the cost of proton and electron participation in the redox reactions. A constant of acid dissociation reaction and a redox reaction of an external electrode, such as the standard hydrogen electrode (SHE), serve as references for the electron and proton energy cost calculations, respectively. More technical information can be found in the supplementary materials. In this type of calculation, the traditional density functional theory (DFT) is used with an implicit solvation model, which is computationally more efficient than CDFT-AIMD. observations that measure the number of involved proton and electron at a certain pH. Furthermore, our results indicate that for a sequential double-ET, such as our CDFT-AIMD simulations, an increase in applied electrochemical potential is required for the second ET.