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.
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This work was supported by the Priority Research Centers Program through the National Research Foundation of Korea ( 2009-0093823 ) and by the Energy & Resource Recycling Program of the KETEP grant funded by the Korean Ministry of Knowledge Economy ( 2008k01600 ).
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