A Facile One-step Synthesis of Co9S8 Electrocatalyst for Oxygen Reduction Reaction

A Co-based chalcogenide electrocatalyst has been synthesized by a facile one-step reaction of dodecacarbonyltetracobalt [Co4(CO)12] and elemental sulfur in 1, 6-hexanediol solvent under refluxing conditions. The characterizations of the synthesized compound were performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD shows the formation of cubic structure Co9S8 and SEM micrograph displays cauliflower-like surface morphologies. The catalyst has an open circuit potential (OCP) of 0.75 V (vs. NHE) and shows a promising catalytic activity for the oxygen reduction. The transfer coefficient and Tafel slope are calculated to be 0.50 and 119 mV in the potential region limited by charge transfer kinetics, respectively. The catalytic activity and the electrochemical stability of the catalyst have also been compared with a commercial Pt catalyst.