Having observed the notable differences between catalysts A, B, and C in ORR intermediate energies, we considered next the effects of functional group modifications.Figure : Left: Functional groups used to modify catalysts In order to understand how these catalysts differ in their ORR scaling relations, we generated a pair plot to visualize the correlations between all intermediate reaction steps in the catalytic cycle (Figure ). The subplots along the diagonal of Figure show the density of catalysts spread across intermediate step reaction energies, whereas the off-diagonal subplots show how correlated the energies of two different reaction steps are for a given catalyst. This representation of the data is useful for visualizing correlations between all reaction energies in the catalytic cycle. Figure depicts two scaling relations that hold across all three of the catalysts: the steps 𝑅 → 𝑅 -𝑂 # vs 𝑅 -𝑂𝐻 → 𝑅 with a correlation coefficient of 0.82, and 𝑅 -𝑂 # 𝐻 → 𝑅 -𝑂 vs 𝑅 -𝑂 → 𝑅 -𝑂𝐻 with a correlation coefficient of 0.92. The former is analogous to the well-known tradeoff between strong and weak oxygen binding catalysts, whereas the latter has received less attention because neither step is typically a thermodynamic barrier in the catalytic cycle. This second correlation is nonetheless important because it depicts why the unnecessarily exothermic oxygen-oxygen bond breaking is difficult to optimize: as 𝑅 -𝑂 # 𝐻 → 𝑅 -𝑂 moves closer to the optimal -1.23 eV, 𝑅 -𝑂 → 𝑅 -𝑂𝐻 is already below -1.23 eV. Similar to other known scaling relations, this one must also be broken to obtain the optimal catalyst. Although the epoxide intermediate for catalyst C-1 does not break the scaling relation involving 𝑅 -𝑂 # 𝐻 → 𝑅 -𝑂 vs 𝑅 -𝑂 → 𝑅 -𝑂𝐻, it does create a bimodal distribution visible on the diagonals of Figure for each of the reactants where the epoxide is present as either the initial or final state.