Bimetallic ZIF derived Co nanoparticle anchored N-doped porous carbons for an efficient oxygen reduction reaction

Abstract

Five isostructural, new bimetallic ZIF precursors with various Zn/Co ratios were successfully synthesized to derive a series of N-doped porous carbons embedded with Co nanoparticles. We systematically investigated the effect of different bimetal ratios in ZIF precursors on the electrocatalytic properties of the obtained porous carbon catalysts. The optimised material Zn₂Co₁-NPs@NC sample demonstrated excellent oxygen reduction reaction performance with a half-wave potential (E_1/2) of 0.849 V, superior to that of commercial Pt/C, and the electron transfer number was 3.98 at 0.2 V to 0.5 V, exhibiting a nearly four-electron selectivity. Furthermore, by exploring the current–time chronoamperometric response over 40 000 s, it is shown that the long-term stability of Zn₂Co₁-NPs@NC was much better than that of the commercial Pt/C.