Continuum simulations were then used to assess the accuracy of the traditional Tafel analysis (see Section S7.1 of the SI) for simulated polarization curves where mass transport or competitive reactions were relevant. Figure -b depict the results of performing traditional Tafel analysis to extract the kinetic parameters from CO polarization curves generated by the simulation, all of which possess a constant CO Tafel slope but different values of 𝐿 () (Figure ), or 𝑖 ",. ! (Figure ). As can easily be seen, even though the CO Tafel slope should be identical for all plotted polarization curves, the apparent Tafel slope as measured by a traditional approach is different for every curve, revealing the extent to which mass transport affects the apparent Tafel slope. Therefore, the continuum model is necessary to deconvolute the effects of mass transport from the intrinsic kinetics of the surface reactions. Intriguingly, when the apparent CO Tafel slope (Figure ) and 𝑖 ",+, (Figure ) are plotted against 𝐿 () , they approach their intrinsic values as 𝐿 () approaches zero. In other words, in the limit of no mass-transport losses of CO2, traditional Tafel fitting is sufficient and accurate.