Abstract
Spinel cobalt ferrite is one of the promising electrocatalysts for the ORR, but the poor electrical conductivity limits its application. Herein, we report a simple and efficient method to synthesize the N-doped carbon-shielding CoFe-rich CoFe2O4 catalyst which exhibits superior ORR catalytic activity under alkaline conditions due to the improved conductivity and high electrochemically active surface area. The NC@CoFe–CoFe2O4 catalyst shows a positive onset potential (1.0 V), half-wave potential (0.89 V) and maximum limiting current density (−5.0 mA cm−2), which are similar to commercial Pt/C, while significantly higher than those of all other controls and most of the previously reported catalysts. The Koutecky-Levich equation and rotating ring-disk electrode test prove a direct four-electron reduction process. Moreover, the NC@CoFe–CoFe2O4 catalyst also demonstrates superior methanol tolerance and long-term stability compared to Pt/C. The proposed catalytic mechanism analysis illustrates that the excellent ORR electrocatalytic activities and durability are the combined effect of highly conductive CoFe alloy, abundant Co–N/Fe–N sites along with the hydrophilic nature of CoFe2O4 clusters.
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•A novel N-doped carbon shielding CoFe-rich CoFe2O4 catalyst is fabricated by a facile method.•The NC@CoFe–CoFe2O4 catalyst exhibits a positive onset potential, half-wave potential and high limiting current density.•The NC@CoFe–CoFe2O4 catalyst also demonstrates superior anti-poisoning capacity and long-term stability.•The superior ORR activity is attributed to the synergy of high conductivity, abundant active sites and good hydrophilicity.