Importantly, this work shows that the experimental Tafel slope is only captured here by explicitly including CO 2 dipole-field interactions when modeling the electrochemical kinetics. Another situation which requires the detailed accuracy of a 1p-mkm is the senstitive kinetic competition that often arises in questions of electrocatalytic selectivity. For example, one of us recently discussed such a competition within a "desorption-re-adsorption-reaction" mechanism to explain the selectivity towards acetate during CO electro-reduction over Cu . The mechanism focuses on a specific surface-bound reaction intermediate and competing routes forward: continued conversion at the surface vs desorption and a subsequent solution reaction to form an early partially-converted product. This competition can only be resolved via a diffusioncoupled 1p-mkm which, in the case of acetate, yielded an intricate dependence upon potential, pH, and catalyst roughness ρ. The simulated selectivity is plotted in Fig-