Graphite-Conjugated Pyrazines as Molecularly Tunable Heterogeneous Electrocatalysts

Condensation of ortho-phenylenediamine derivatives with ortho-quinone moieties at edge planes of graphitic carbon generates graphite-conjugated pyrazines (GCPs) that are active for oxygen reduction electro-catalysis in alkaline aqueous electrolyte. Catalytic rates of oxygen reduction are positively correlated with the electrophilicity of the active site pyrazine unit and can be tuned by over 70-fold by appending electron-withdrawing substituents to the phenylenediamine precursors. Discrete molecular analogs containing pyrazine moieties display no activity above background under identical conditions. This simple bottom up method for constructing molecularly well-defined active sites on ubiquitous graphitic solids enables the rational design of tunable heterogeneous catalysts.