Synergy between Heterobimetallic Active Sites in Hybrid Bilayer Membranes Enhances the Electrocatalytic Activity and Product Selectivity of O2 Reduction

The development of proton exchange membrane fuel cells is hindered by the sluggish O2 reduction reaction (ORR) kinetics. At present, precious metal catalysts are unable to enhance the ORR kinetics efficiently. To address this challenge, hybrid bilayer membranes (HBMs) with non-precious catalytic sites have been developed to independently control proton and electron transfer kinetics in ORR. Inspired by the structural properties of oxidases, a biomimetic CuFe active center was examined as an ORR electrocatalyst. This bimetallic HBM displayed an ORR activity that is 1.4 times higher than the monometallic systems and the highest Faradaic efficiency for H2O (~94%) among Cu-, Fe-, Ni-, and Co-based HBMs. Further investigation into H2O2 reduction revealed a parallel 2e–+2e– mechanism, highlighting the synergistic effect of the CuFe site in catalyzing ORR. These findings are envisioned to spark future rational design and optimization of catalysts for more efficient electrochemical processes.