Preparation of a High-Performance Fe–N–C Electrocatalyst from an MOF Precursor for ORR Toward Zinc–Air Batteries

Metal–air batteries can be developed on a large scale using suitable nonprecious metal catalysts to replace Pt/C in the cathode electrode. The production of an iron-based N-doped carbon electrocatalyst (Fe–NC) from a metal–organic framework precursor through the pyrolysis process was successfully achieved in this work. Brunauer–Emmett–Teller analysis of the Fe–NC electrocatalyst showed a large surface area (621 m² g^–1). X-ray photoelectron spectroscopy and Raman results confirmed the existence and variety of nitrogen species in the structure of the electrocatalyst as defect agents, and active sites induced astounding oxygen reduction reactions as efficient cathodes for zinc–air batteries. The electrochemical test in the 0.1 M KOH solution displayed that the oxygen reduction cathodic peak appeared at 0.897 V_RHE. The linear sweep voltammetry revealed excellent onset potential (E_onset = 1.02 V_RHE), half-wave potential (E_1/2 = 0.892 V_RHE), and limiting current density (4.87 mA cm^–2). The durability test of the Fe-NC electrocatalyst indicated only a 22 mV negative shift in the E_1/2 after 10,000 continuous potential cycles. The open circuit voltage and specific capacity of Fe–NC were 1.47 V and 749 mA h g^–1 in a Zn–air battery system, respectively. Due to the acceptable oxygen reduction activity of the synthesized electrocatalyst, the Fe–NC electrocatalyst can be used in a wide range of energy applications.