Macro-to-micro level modulation of MOF-derived Fe single-atom catalysts with CNT for high-performance Zn–air batteries

Single-atom catalysts (SACs) have attracted considerable attention as promising substitutes for noble metal catalysts in the oxygen reduction reaction (ORR) due to their exceptional atom utilization efficiency and tunable coordination environments. SACs are typically supported on conductive materials to enhance electron transport , with carbon nanotubes (CNTs) commonly used for this purpose. However, this study revealed that CNTs play a dual role: improving conductivity and modulating the coordination structure of SACs. Using advanced X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations, we demonstrated that CNTs alter the Fe N bond length and increase the structural instability, resulting in enhanced intrinsic catalytic properties of MOF-derived Fe N 3 SACs (FeSA@NC/CNT). Correspondingly, electrochemical analyses confirm that the ORR performance of FeSA@NC/CNT is comparable to that of commercial Pt/C catalyst, achieving a half-wave potential of 0.87 V and a kinetic current density of 4.12 mA cm −2 at 0.9 V. In Zn–air batteries, FeSA@NC/CNT achieves a maximum power density of 188 mW cm −2 and a specific capacity of 823 mA h g Zn −1 , along with remarkable stability over 600 charge–discharge cycles. This study highlights the transformative potential of CNT integration into SAC catalysts and establishes a new pathway for the development of sustainable energy technologies. MOF-derived FeSA with threaded CNTs enhance ORR activity by improving conductivity, mechanical strength, and active site density. Strong MOF-CNT interactions optimize Fe SAC coordination, enabling superior ORR performance and stable Zn-air battery capacity. • MOF-derived FeSA catalysts synthesized with CNTs forming a threaded structure • Morphological change via CNT integration boosts ion and gas transport. • CNT incorporation increases Fe-N 3 bond length and active site density. • Achieves superior ORR activity with 12.9 mA cm −2 kinetic current density at 0.85 V • Outperforms Pt/C in Zn-air batteries, achieving 188 mW cm −2 power density