Cobalt-Based Multicomponent Oxygen Reduction Reaction Electrocatalysts Generated by Melamine Thermal Pyrolysis with High Performance in an Alkaline Hydrogen/Oxygen Microfuel Cell

A series of cobalt-based multicomponent electrocatalysts (Co-Cat-T) for the oxygen reduction reaction (ORR) were synthesized by thermal pyrolysis of activated carbon-supported cobalt and melamine mixture from 500 to 800 degrees C. Their corresponding electrocatalytic performance was systematically investigated toward ORR in an alkaline electrolyte. The electrocatalyst chemical composition and structure evolution (e.g., microstrain, crystallite size, and cell volume) were confirmed by X-ray diffraction Rietveld analyses. The material generated at 550 degrees C (Co-Cat-T550) showed the largest cell volume of the C3N4 phase with a crystallite size of 4.1 +/- 0.1 nm. Independent of the heat-treatment temperature, the cobalt atom was coordinated to nitrogen moieties. The following findings: cobalt inserted in the carbon nitride framework (Co-g-C3N4), abundant Co-N-x and pyridinic-N species, unique encapsulated cross-tubular structure, and disordered carbon domains performed better in the ORR with Co-Cat-T550 among the obtained electrocatalysts. In addition, Co-Cat-T550 showed performance comparable to Pt/C in an alkaline hydrogen/oxygen microfuel cell platform.