shows the most dramatic, exponential dependence coming from the competing reaction barriers ∆G ‡ rdx (U ), ∆G ‡ des , and ∆G ‡ ads , as well as from the electrode potential U (indirectly through ∆G ‡ rdx ). This exponential dependence follows that of the resulting reaction rates and can change the selectivity towards X(aq) from 100% to 0% within only few hundred millivolts of increasing overpotential (SI, Fig. ). In comparison, the effect from varying catalyst morphology is weaker and emerges as an asymptotic ∝ 1/ρ dependence in selectivity. This relation is founded in the competition between diffusion and re-adsorption: the probability of X ( * ) re-adsorption increases linearly with ρ, thus leading to more of the final product and less of the volatile intermediate product. Albeit weaker than the dramatic response to U , the role of ρ can still be crucial to catalytic performance as will be demonstrated in the following. Finally, when chosen within physically reasonable ranges (SI, Fig. ), the remaining transport-related parameters (D diff , L diff , and H s ) generally influence selectivity to a much lesser extent. For example, exchanging the D diff value of acetaldehyde (13.75 x 10 -10 m 2 • s -1 ) to that of CO (20.3 x 10 -10 m 2 • s -1 ) will typically only increase selectivity towards the diffusing intermediate product by <10%.