Enhancing oxygen reduction on a bimetallic Ag-Fe-N-C electrocatalyst for a zinc-air battery

Abstract

Bi-metallic organic frameworks (MOFs) have been rarely reported to be functioned as non-platinum (Pt) electrocatalysts for oxygen reduction reaction (ORR). In this work, here we synthesize a carbon-based bimetallic Ag-Fe-N-C electrocatalyst for the ORR by jointly introducing Ag and Fe ions into the internal structure of MOFs derived from zinc acetate and 2-methylimidazole (2-MIM). The Ag-Fe-N-C catalyst possesses a porous carbon network structure with an specific surface area of 961.3 m2g−1, which is woven by carbon nanotubes/layers-encapsulated Fe3C or Ag nanoparticles. This catalyst has demonstrated a distinguished ORR catalytic activity with a half-wave potential of 0.883 V (vs. RHE) and an outstanding stability in an alkaline electrolyte. In addition, it gained a higher peak power density of 211 mWcm−2 and specific energy density of 875 Whkg−1Zn, a narrower charge-discharge potential gap of 77 mV and a better catalytic durability compared to the corresponding Pt/C-based zinc-air batteries. Our results may provide a facile strategy for activity enhancement of carbon-based ORR electrocatalysts via the controllable doping of bi-metallic ions.