Desirable Pore Connectivity Effects in Multiscale Interactive Cobalt Centers with Asymmetric B/N-Coordination Carbon for Promoting Zn-Air Batteries.

Abstract

Cobalt-based catalysts have demonstrated promising performance in both the oxygen reduction/evolution reaction (ORR/OER), positioning them as potential dual-functional catalysts for recharging Zn-air battery. However, the long-standing challenge remains in achieving satisfactory dual-functionality and stability of these cobalt metal centers. Herein, bicontinuous structured nanofibers composed of multiscale cobalt embedded in asymmetric B/N-coordination carbon (denoted as CoBNPCF-900) are constructed, exhibit enhanced ORR/OER activity, and enable the effective operation of zinc-air battery. The utilization of 3D tomograph reconstruction and absolute permeability experiment simulation unravels a "pore connectivity" effect from visualizing the intricate internal porous structure and comprehending the fluid flow within internal passages. Theoretical calculations further elucidate the electronic transfer tendency and spin polarization of CoBNPCF-900, providing a rationale for the improved performance resulting from alterations in the electronic environment surrounding active Co sites embedded in asymmetric B/N-coordination carbon. A homemade rechargeable zinc-air battery using CoBNPCF-900 as the air cathode exhibits a bifunctional overpotential of 0.808 V and a battery lifetime exceeding 1706.6 h, which is superior to that of the Pt/C+RuO₂ catalysts (526 h). This study offers new insights into constructing catalysts with 3D spatial precision and provides strong references for practical applications in energy storage and conversion electrocatalysts.