Fe-based electrocatalysts are elegant due to their better performance towards the oxygen reduction reaction. Nevertheless, they commonly contain different moieties, for example Fe-Nx , Fe, Fe3 C and N-doped carbon, primarily the debatable assistance of these components towards ORR electrocatalysis, specifically for intermediate peroxide reduction reactions (PRR). In this paper, to explore the role of Fe-Nx centres for PRR, a Fe-N-C electrocatalyst rooted in nitrogen-doped carbon nanotubes with mesoporous structures was synthesized from a Fe/Zn-dicyanoimidazolate framework. The use of dicyanoimidazole coordinated with iron can introduce the Fe-Nx active sites as well as directional N-doped carbon nanotubes, which is good for enhancing electronic conductance of the catalyst. The attained electrocatalyst shows tremendous enactment to ORR, being comparable to the activity of Pt/C in acidic and better in alkaline electrolytes. This study also reveals that Fe-Nx active centres are responsible for less H2 O2 production. Though the Fe-Nx moieties and Fe3 C/Fe particles encapsulated N-doped carbon, both are active centres for ORR, however, Fe-Nx sites are more active than others for peroxide reduction reaction. These perceptions suggest rational methodologies for more active and consequently further durable Fe-N-C catalysts.
Keywords: electrocatalysis; fuel cells; mesoporous carbon; metal-organic framework; oxygen reduction reaction.
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