In order to predict the ORR activity of the catalysts in this study, we initially had to find the location of their active sites. Ricke et al. observed in a previous study that localized spin density of the oxidized species indicated the active site on a GCC very similar to catalyst A in this study, so we plotted the spin density on each of the more novel catalysts B and C (Figure ). For catalyst B, the highest spin density is localized on a single carbon atom, whereas for catalyst C there are two carbon atoms that have relatively similar spin densities. We placed O2 near each sp 2 carbon atom in the catalytic region of these molecules and found that the only atoms that bound O2 favorably were the very same carbons indicated by the spin density localization (Figure ).