Synergistic dual sites of Zn–Mg on hierarchical porous carbon as an advanced oxygen reduction electrocatalyst for Zn–air batteries

Abstract

The development of cost-effective and high-performance non-noble metal catalysts for the oxygen reduction reaction (ORR) holds substantial promise for real-world applications. Introducing a secondary metal to design bimetallic sites enables effective modulation of a metal–nitrogen–carbon (M–N–C) catalyst's electronic structure, providing new opportunities for enhancing ORR activity and stability. Here, we successfully synthesized an innovative hierarchical porous carbon material with dual sites of Zn and Mg (Zn/Mg–N–C) using polymeric ionic liquids (PILs) as precursors and SBA-15 as a template through a bottom-up approach. The hierarchical porous structure and optimized Zn–Mg bimetallic catalytic centers enable Zn/Mg–N–C to exhibit a half-wave potential of 0.89 V, excellent stability, and good methanol tolerance in 0.1 M KOH solution. Theoretical calculations indicated that the Zn–Mg bimetallic sites in Zn/Mg–N–C effectively lowered the ORR energy barrier. Furthermore, the Zn–air batteries assembled based on Zn/Mg–N–C demonstrated an outstanding peak power density (298.7 mW cm⁻²) and superior cycling stability. This work provides a method for designing and synthesizing bimetallic site catalysts for advanced catalysis.