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ZrO2-embedded N-enriched carbon catalyst for alkaline oxygen reduction reaction

The use of transition metal oxides is a promising strategy for accelerating the sluggish kinetics of the oxygen reduction reaction (ORR) in zinc–air batteries. Herein, we propose a facile and cost-effective strategy to synthesize a ZrO2/doped-N carbon (ZrO2/NC) catalyst with high N and Zr contents (8.78 and 4.4 atom%, respectively). The ZrO2/NC catalyst exhibits comparable electrocatalytic activity with a half-wave potential of 0.815 V and better durability in the ORR compared to the commercial Pt/C catalyst. The ORR proceeds via a 4e− transfer pathway under alkaline conditions in the presence of this catalyst. The excellent catalytic performance is attributed to the high densities of the active sites, namely, pyridinic-N, graphitic-N, and Zr. The high Brunner–Emmett–Teller surface area (787.4 m2/g) and an amorphous-crystal morphology of the ZrO2/NC catalyst favored the rapid mass transfer and exposed the active sites of the electrolyte and reactants. The strategy presented herein can be used for the large-scale production of metal–air batteries.