Investigation of Carbon Materials as Supports for Metalloporphyrins Used for Cathode Catalyst in Fuel Cells

Abstract

meso-Substituted cobalt porphyrins adsorbed on carbon materials were prepared by using a homogenizer in mixing cobalt tetraethylporphyrin and various carbon materials. These electrocatalysts gave rise to electroreduction of O₂ at a remarkably positive potential (E_p = 0.44 V versus saturated calomel electrode (SCE)) and showed a high selectivity for the four-electron reduction (n = 3.9). The catalyst heat-treated at 600°C showed higher potential (E_p = 0.44 V vs. SCE). Electrochemical study and X-ray photo spectroscopy (XPS) analysis revealed that the adsorbed amount of cobalt-porphyrin molecules caused highly effective catalysts for electroreduction of O₂.