Self-Sacrificial Copper Cluster-Catalyzed Oxygen Reduction: A Paradigm Shift in Zinc-Air Battery Technology

Abstract

Metal-ion decorated covalent organic frameworks (M-COFs) are prepared by reacting aldehyde-terminated Cu(I) clustered monomers and amine-terminated triazine monomers through imine linkages, and the as-prepared Cu(I) cluster-based COF is analyzed and tested for its electrocatalytic activity toward oxygen reduction reactions. These M-COFs are more stable and active under adverse conditions. The annealed sample (ACu-COF) displays an increased surface area of 120 m²g⁻¹ compared to the pristine sample Cu-COF (19 m²g⁻¹). Because of its larger specific surface area, and active nitrogen content, the annealed counterpart with flower morphology exhibits exceptional oxygen reduction reaction (ORR) capabilities. The ACu-COF sample demonstrates a nearly four-electron ORR process, an onset potential of 0.92 V versus reversible hydrogen electrode (RHE), and a diffusion limiting current density of 3.85 mA cm⁻². It also reached a half-wave potential of 0.78 V versus RHE. After 2000 cycles, the onset potential of the ACu-COF only dips by 28 mV, demonstrating its remarkable long-term durability. Additionally, the homemade primary zinc-air battery employing ACu-COF produces a specific capacity of 747 mAh g⁻¹ and a maximum peak power density of 133 mW cm⁻².