Synthesis of Cobalt Complex Using Pyrrole Derivative with Basic Ligand and Application to Cathodic Catalyst for Oxygen Reduction

A ligand compound with strong coordinating property, 2-(1H-pyrrole-3-yl) pyrazine (pz-Py), was synthesized to increase the density of active sites for oxygen reduction. The obtained compound was coordinated with cobalt (II) ions strongly. It was revealed that the metal complex could be used as a cathode catalyst in fuel cells. The potential for oxygen reduction was positive (Ep=0.27 V vs SCE) for the catalyst prepared by refluxing the corresponding compound, cobalt acetate tetrahydrate, and the carbon particles. This activity was superior to CoPy/C which was synthesized by refluxing pyrrole, cobalt acetate tetrahydrate, and the carbon particles, and it was shown that nitrogen atoms of pyrazine type contribute accumulation of cobalt ions. The activity of the catalyst was improved after heat treatment under Ar gas. These results show the potential use of the present catalyst as a novel cathode catalyst in fuel cells.