Abstract
Novel Co-N-S/C catalysts supported on carbon were obtained using a two-step procedure. The procedure consisted of the synthesis of a carbon-supported Co-2-mercaptobenzothiazole (denoted as Co-MBT/C) complex using a solvent-milling method and the pyrolysis of the Co-MBT/C complex. 2-Mercaptobenzothiazole (MBT) was used as the nitrogen and sulfur ligand for Co-MBT complex formation. X-ray diffraction (XRD), TEM, EDS and elemental mappings were used to characterize the structure changes in these catalysts before and after the heat-treatment. Several catalysts were synthesized by varying the amount of cobalt salt and pyrolysis temperature. The results showed that the optimal cobalt salt content and pyrolysis temperature were around 25 wt% and 800°C. Under the optimal conditions, an onset potential of 0.20 V and a half-wave potential of 0.05 V were reached in an alkaline electrolyte, and the Co-N-S/C catalyst possessed high catalytic activity and catalytic stability towards an oxygen reduction reaction (ORR). These results indicated that Co-N-S/C is a promising catalyst for the ORR.
