Hollow porous nitrogen-doped carbon formed by fe-modified bimetallic organic framework for rechargeable liquid/solid Zn-air batteries

Abstract

The rational design of non-precious metal-carbon materials for Zn-air batteries (ZABs) has gained immense attention in the recent decade. In this report, a Fe-Co-hollow porous nanocarbon material derived from Fe-modified bimetallic zeolitic-imidazole frameworks (ZIFs) has been demonstrated. Owing to the unique 3-dimensional interconnected hollow porous carbon structure of the developed material and the synergetic effect of the corresponding bimetallic system, it shows good bifunctional oxygen electrocatalytic properties. Compare to the commercial 20% Pt/C and IrO2 or RuO2, the half-wave potential of oxygen reduction reaction (ORR) of the developed catalyst reaches 0.81 V (vs. RHE) (Pt/C is 0.84 V vs. RHE), and the overpotential of oxygen evolution reaction (OER) at 10 mA/cm2 is 0.43 V vs. RHE (the overpotential of RuO2 of 0.4 V vs. RHE). When the rechargeable liquid Zn-air batteries are assembled with the catalysts as the cathode, it shows a power density of 100.2 mW/cm2 and cycling stability of 2500 min, which are better compare to the commercial Pt/C-RuO2 (the power density and cycling stability of Pt/C-RuO2 is 99.2 mW/cm2 and cycling stability of 2200 min, respectively). In addition, the open-circuit potential (OCP) of the produced rechargeable liquid and flexible solid-state ZABs reach up to 1.47 V and 1.45 V, respectively; also, the material exhibits good bending flexibility and stability. Overall, this development provides a new method for solid-state ZABs systems of MOF-derived carbon materials.