Electrochemical analysis of charge mediator product composition through transient model and experimental validation

Charge carriers have been studied for use in applications such as fuel cells, redox flow batteries, and electrochemical CO₂ reactors for conversion to value-added products. Here, transient-based equilibrium models are developed for two well-known charge carriers: methyl viologen (MV) and ethyl viologen (EV). The models are simulated using Butler-Volmer kinetics until steady-state is reached. EV is favored over MV due to lower dimerization, and enabling over 2 × production of reduced EV⁺ over MV⁺. MV and EV products do not appear to significantly change, except only under sufficiently acidic conditions (pH < 4). Charge and energy input requirement are used to assess total system efficiency and potential for system scale-up via chronoamperometry. The charge and energy analysis performed with EV as the charge carrier reveals that optimal charging voltage is around − 0.8 to − 0.85 V vs. Ag/AgCl, which is above the minimum reduction voltage (around − 0.6 to − 0.7 V vs. Ag/AgCl) and suggest more favorable conditions for performing such charge carrier reductions. Graphical abstract: [Figure not available: see fulltext.]