More re-adsorption favors continued surface reaction and lowers the selectivity towards the partially-converted product. Considering its simplicity, our kinetic model captures this effect with almost remarkable agreement to experiment. The theoretical predictions (using model parameters listed in SI, Table ) are represented by the solid red lines in Fig. and show the anticipated ∝ 1/ρ dependence discussed in the previous section. These curves largely reproduce the experimental trends. Deviation is most noticeable only under conditions of ultra-low catalyst loading (ρ < 0.2) in Fig. (a). The model's over-estimation of the experimental H 2 O 2 selectivity may be attributed to an inhomogeneous distribution of catalyst particles that cannot be described by our effective, one-dimensional ρ descriptor. The experiment-theory comparison is likely further skewed here by a more complex dependence on the applied electrode potential than that predicted by the "desorption-re-adsorptionreaction" mechanism (SI, Sec. S3.1). This potential dependence has been previously discussed for the Pt-based eORR as the result of multiple competing reaction paths (that do not go through the volatile H 2 O 2 intermediate), but such mechanistic intricacies go well beyond the scope of our simple model and are not further discussed.