Engineering interconnected hierarchical porous carbon frameworks supported FeNi bimetallic sites for enhanced bifunctional oxygen electrocatalysis

Carbon-supported bimetallic sites show great potential in the field of oxygen reduction electrocatalysis, yet multi-scale structural engineering of carbon supports plays an important role in modulating the catalytic activity. Herein, we ingeniously synthesized an interconnected multi-dimensional porous carbon matrixs supported FeNi bimetallic catalyst (denoted by FeNi-NC/CNT) through pyrolyzing ZIF-8 precursors mixed with polystyrene (PS) microspheres as a pore-forming agent and carbon nanotubes. The optimized FeNi-NC/CNT catalyst exhibited exceptional bifunctional catalytic activity with high half-wave potential E 1/2  = 0.87 V in the oxygen reduction reaction (ORR) process and high activity in the oxygen evolution reaction (OER) with E j=10  = 1.60 V, leading to an ultralow potential difference (730 mV) that is much lower than that of control sample (843 mV) without PS perforation. In practical application, the FeNi-NC/CNT based zinc-air battery achieved a peak power density of 148.6 mW cm −2 and a steady operation time exceeding 150 h, with a low potential difference of only 950 mV. The enhanced bifunctional catalytic activity can be attributed to multi-dimensional frameworks composed of hierarchical porous carbons and conductive CNTs, provide adequate exposure to active sites and mass/electron transfer pathway, and the tuned interaction of FeNi that contributes to equilibrating the intrinsic ORR/OER bifunctional catalytic activity. Graphical abstract