Exploring Scaling Relations and Active Site Specificity of Graphite-Conjugated Catalysts Using Density Functional Theory

Graphite-conjugated catalysts (GCC) are a class of highly synthetically tunable materials with properties of both homogeneous and heterogeneous catalysts. GCCs have proven especially promising for catalyzing the oxygen reduction reaction (ORR). In this study, we applied density functional theory (DFT) to explore how functional group and aromatic scaffold modifications affect catalytic activity of GCCs for ORR. We found that both kinds of modifications can have a significant enough effect on catalytic activity to tune the ORR rate determining step between the strong and weak oxygen binding regimes. Further, we found that DFT predicts certain GCC scaffolds could have an epoxide intermediate during the catalytic cycle instead of the more usually predicted atomic oxygen bound to a single site. We also investigated patterns in the effects of functional group modifications, and under what conditions it is possible to break scaling relations for these catalysts. Our findings provide a deeper understanding of why ORR activity is limited to specific aromatic carbon active sites in GCCs, elucidating general principles for designing ORR catalysts with nitrogen-doped aromatic carbon materials.