Development of highly active and stable non-precious oxygen reduction catalysts for PEM fuel cells using polypyrrole and a chelating agent

Nitrogen-modified carbon nanofibers to be used as catalysts in the oxygen reduction reaction (ORR) were synthesized by pyrolysis in the presence of cobalt with PPy and a chelating agent, such as ethylenediamine (ED). It has been found that the type of nitrogen source has a remarkable impact on the catalytic activity and stability of ORR catalysts. XPS and elemental analysis indicated that the combination of ED and PPy as nitrogen sources provided a synergistic effect toward increasing the total nitrogen content of the catalysts and the content of useful nitrogen functional groups such as pyridinic-N and graphitic-N that are responsible for high ORR activity and stability in acidic environments. (C) 2011 Elsevier B.V. All rights reserved.