Highly uniform and monodisperse carbon nanospheres enriched with cobalt–nitrogen active sites as a potential oxygen reduction electrocatalyst

Abstract

Abstract Uniform cobalt and nitrogen co-doped carbon nanospheres (CoN–CNS) with high specific surface area (865 m 2 g −1 ) have been prepared by a simple but efficient method. The prepared CoN–CNS catalyst exhibits outstanding catalytic performance for the oxygen reduction reaction (ORR) in both alkaline and acidic electrolytes. In alkaline electrolyte, the prepared CoN–CNS has more positive half-wave potential and larger kinetic current density than commercial Pt/C. In acidic electrolyte, CoN–CNS also shows good ORR activity with high electron transfer number, its onset and half-wave potentials are all close to those of commercial carbon supported platinum catalyst (Pt/C). CoN–CNS catalyst shows more superior stability and higher methanol-tolerance than commercial Pt/C both in alkaline and in acidic electrolytes. The potassium thiocyanate-poisoning test further confirms that the cobalt-nitrogen active sites exist in CoN–CNS, which are dominating to endow high ORR catalytic activity in acidic electrolyte. This study develops a new method to prepare non-precious metal catalyst with excellent ORR performances for direct methanol fuel cells.