Iron phthalocyanine coupled with Co-Nx sites in carbon nanostraws for Zn-Air batteries

The energy crisis heightens interest in proton exchange membrane fuel cells (PEMFCs), where the oxygen reduction reaction (ORR) is a critical cathodic process hindered by its intrinsic sluggish kinetics. Single-atom catalysts (SACs) at the molecular level, notably those featuring an Fe-N 4 structure derived from iron phthalocyanine (FePc), exhibit significant potential but confront the challenges of aggregation and inadequate electrical conductivity. Herein, we present a novel FePc coupled with defect-rich CoN x -doped hollow carbon nanostraw derived from cobalt-doped indium-based metal–organic frameworks (MOFs). This enhancement is attributed to the CoN x structure’s effective modulation of the Fe-N 4 active sites, further complemented by the hollow nanostraw structure, which significantly increases the accessibility of active sites, thereby promoting enhanced catalytic performance. FePc@HCoNC demonstrates exceptional ORR performance with an oxygen reduction potential of 0.903 V, half-wave potential of 0.914 V, and limiting current density of 5.18 mA cm −2 . For zinc-air batteries (ZABs), FePc@HCoNC achieves an open-circuit voltage of 1.524 V, peak power density of 153.06 mW cm −2 , specific capacity of 758.10 mAh g −1 , and stable cycling for 150 h. These findings underscore its potential as a superior alternative to precious metal-based catalysts, offering a pathway to more sustainable and efficient energy conversion technologies.