Impact of Metal Source Structure on the Electrocatalytic Properties of Polyacrylonitrile-Derived Co-N-Doped Oxygen Reduction Reaction Catalysts.

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The oxygen reduction reaction (ORR) plays a central role in energy conversion and storage technologies. A promising alternative to precious metal catalysts are non-precious metal doped carbons. Considerable efforts have been devoted to cobalt-doped carbonized polyacrylonitrile catalysts, but the optimization of their catalytic performance remains a key challenge. We have proposed a multifunctional active metal source strategy based on the cobalt complex with the ligand containing pyridine and azo-fragments. This complex simultaneously provides the nitrogenous environment for the Co atoms and acts as a blowing agent due to N2 extrusion, thus increasing the surface area and porosity of the material. This strategy provided the catalysts with a high surface area and pore volume, combined with the greater fraction of Co-N clusters, and a lesser amount and smaller size of Co metal particles compared to conventionally prepared catalysts, resulting in improved catalytic performance. In addition to strict 4-electron ORR kinetics and 383 mV overpotential, the novel catalysts exhibit limiting current values close to the Pt/C benchmark and greatly overcome the Pt in methanol tolerance. These results demonstrate the critical role of metal source structure and carbonization parameters in tailoring the structural and electrochemical properties of the catalysts.