Pyrolyzed CoN4-chelate as an electrocatalyst for oxygen reduction reaction in acid media

Abstract

A novel platinum-free electrocatalyst CoTETA/C for oxygen reduction reaction (ORR) was prepared from pyrolysis of carbon-supported cobalt triethylenetetramine chelate under an inert atmosphere. X-ray diffraction (XRD) measurement showed that nanometallic face-centered cubic (fcc) crystalline a-Co phase embedded in graphitic carbon was present on the pore surface of this catalyst. Cyclic voltammogram experiment showed that the ORR peak potential appears at 710 mV (vs. NHE) in oxygen-saturated acidic media (0.5 M H2SO4). The Koutecky-Levich analysis indicated that the ORR follows the first-order kinetic reaction and the ORR proceeds via both the two-electron reduction and the four-electron reduction, while the latter is the main process. The actual performance of a single cell with the obtained CoTETA/C electrocatalyst was examined under a hydrogen-oxygen fuel cell system, and the maximal output power density reached 135 mW cm-2 at 25 °C. © 2009 Professor T. Nejat Veziroglu.