We have also shown that structural and functional group modifications have a limited, although not entirely negligible, capacity to break scaling relations between the first and last step of ORR for GCCs. Intriguingly, the epoxide intermediate we observed does creates a much stronger deviation from the observed trends for the R -O # H + H ! + e " ⇄ R -O + H # O and R -O + H ! + e " ⇄ R -OH steps in the catalytic cycle. Although these steps are not rate limiting for these catalysts, this epoxide intermediate could appear in other nitrogen-doped carbon materials where it could affect catalytic activity. In general, functional group substitutions that caused deviations from the intermediate energy correlations occurred when the modification has a significant effect on the active site. To improve catalytic activity by modifying a known catalyst, one may therefore either take advantage of the predictability of substitutions far from the active site to shift the catalyst along the known scale between strongly and weakly binding active sites, or instead make structural modifications near or directly on the active site to cause more significant changes to activity. This latter method, especially when it changes the way oxygen species bind, seems likely to be the most promising path to breaking scaling relations. This principle is illustrated by the epoxide intermediate at C-2 that binds more strongly than the singly-bound oxyl species in C-1. This epoxide structure's increased binding strength significantly deviates from the expected strength based on scaling relations relative to other oxygen intermediates. While DFT does not predict this specific deviation will lead to an increased activity for this active site, this does suggest the possibility of engineering future GCCs that can be tuned at multiple active sites, designed to specifically break the other scaling relations that are necessary to improve catalytic activity. Future work could consider catalysts designed using Clar structures to place active sites at the correct spacing to bind both oxygen atoms in O2 simultaneously. This intermediate could potentially skip the peroxide intermediate entirely and could increase the binding strength of the initial intermediate without increasing the binding strength of the final hydroxide intermediate, definitively deviating from the known scaling relations. Such a catalyst could then be tuned using derivative modifications predicted by DFT to shift intermediate energies without disrupting binding at the active sites.