Thermodynamic potentials for the reduction of CO to various products is given in the following table versus NHE at pH = 7. Single electron reduction of CO to CO radical occurs at E° = −1.90 V versus NHE at pH = 7 in an aqueous solution at 25 °C under 1 atm gas pressure. The reason behind the high negative thermodynamically unfavorable single electron reduction potential of CO is the large reorganization energy between the linear molecule and bent radical anion. Proton-coupled multi-electron steps for CO reductions are generally more favorable than single electron reductions, as thermodynamically more stable molecules are produced.