Molten salt-assisted synthesis of special open-cell Fe, N co-doped porous carbon as an efficient electrocatalyst for zinc–air batteries

Abstract

Fe, N co-doped carbon electrocatalyst is one of the most attractive alternatives to Pt/C catalysts due to its high catalytic activity, excellent stability and low cost. However, obtaining stable and efficient Fe, N co-doped carbon oxygen reduction reaction (ORR) catalysts based on simple processes is still a challenge. Herein, Fe, N co-doped porous carbon (Fe–N–C) with an open macroporous frame structure is prepared by using inorganic molten salts (FeCl₃·6H₂O and ZnCl₂) and ethylenediaminetetraacetic acid as the template and nitrogen-containing carbon precursor, respectively. The open pore structure of the Fe–N–C material precisely tailored with the inorganic molten salt template exhibits high specific surface area (676.5 m² g⁻¹) and appropriate pore size, which can promote oxygen adsorption and expand the oxygen reduction interface, resulting in the acceleration of the electron/charge transfer processes and an improved electrocatalytic performance. The optimized Fe₃–N–C-800 electrocatalyst exhibits good catalytic activity for ORR, such as high onset potential of 0.998 V and half wave potential of 0.84 V in alkaline media, as well as high stability and methanol tolerance. Furthermore, a novel Zn–air battery assembled with carbon paper containing Fe₃–N–C-800 electrocatalyst as air cathode shows high open-circuit voltage (1.485 V), high specific capacity (870 mA h g⁻¹ at 10 mA cm⁻²), excellent reversibility and stability. The proposed synthetic strategy provides new opportunities to design and construct carbon frame materials with the desired open macroporous structure to improve their electrocatalytic performance.