Constructing Co/Fe-Nx dual-site catalyst based on Co0.72Fe0.28 alloy nanoparticles anchored on hollow hierarchical porous carbon framework for enhanced oxygen reduction reaction and ZABs

Hollow hierarchical porous nitrogen-doped carbon (HNC) derived from ZIF-8@ZIF-67 (ZIF: zeolitic-imidazolate framework) is a promising nanocomposite electrocatalyst rich in active sites. However, the single active species (Co-Nx) constrains its application. By introducing Fe in the precursor preparation, this work increased the active species of the catalyst to Co/Fe-Nx species and Co0.72Fe0.28 nanoparticles. Due to the advantages of abundant active sites and the synergy of multiple active species, Co,Fe-HNC-1 exhibited excellent oxygen reduction reaction (ORR) performance in 0.1 M KOH electrolyte with an onset potential (Eonset = 0.92 V vs. RHE) and a half-wave potential (E1/2 = 0.85 V vs. RHE) comparable to those of commercial Pt/C, as well as better long-term stability and methanol resistance. Meanwhile, Co,Fe-HNC-1 additionally demonstrated oxygen evolution reaction (OER) activity. Co,Fe-HNC-1 also performed well as an air cathode in a zinc-air battery (ZAB) with a peak power density of 85.00 mW cm-2 and outstanding stability with only 1.8 % loss after more than 200 galvanostatic cycles at 10 mA cm-2. This work provides a new perspective for the rational design and preparation of electrocatalysts based on HNC nanocomposites.