Dual-Template-Assisted Pyrolysis Strategy to Construct Iron-Nitrogen Co-Doped Porous Carbon Catalysts for High-Performance Zn–Air Batteries

Abstract

Zinc–air batteries (ZABs) have attracted much attention because of their high energy density, low cost, and excellent safety. However, developing inexpensive oxygen electrocatalysts with stable performance and fast reaction kinetics remains challenging. Herein, a simple and versatile dual-template-assisted pyrolysis strategy to prepare iron-nitrogen co-doped porous carbon (R-Fe-N-C) catalysts using magnesium carbonate hydroxide (Mg₂(OH)₂CO₃) as a self-generated template, ferrocene as an iron source, ethylenediaminetetraacetic acid disodium zinc salt (EDTA-Na₂Zn) as a carbon source, and 1,10-phenanthroline as a nitrogen source is proposed. During the pyrolysis process, Mg₂(OH)₂CO₃ can be decomposed to generate MgO nanoparticles as self-generated hard template embedded in the carbon skeleton, and finally removed by acid etching to form a rich mesoporous structure. Meanwhile, the Zn species in EDTA-Na₂Zn can form rich micropores after high-temperature evaporation. Thus, the R-Fe-N-C catalyst reaches a high half-wave potential of 0.874 V and good stability, which is better than commercial Pt/C. In addition, ZABs with R-Fe-N-C as air cathode exhibit high open circuit voltage of 1.52 V and a maximum power density of 122.9 mW cm⁻², as well as good cycle stability over 110 hr. The proposed synthesis strategy provides an effective way for designing metal-heteroatomic-doped porous carbon materials.