Ligand engineering of Co-MOF-74 with hexaaminotriphenylene for enhanced oxygen reduction reaction in zinc-air batteries

Zinc-air batteries hold great promise as a next-generation efficient and environmentally friendly energy technology. However, the sluggish kinetics of the oxygen reduction reaction (ORR) process pose a significant challenge to their development. To address this issue, atom dispersion catalysts are developed to maximize the utilization of metal active centers. Metal-organic frameworks (MOFs) are a series of molecular materials with high atomic-level dispersion metal utilization, but they often lack sufficient electrical conductivity. Their application in MOF electrocatalysis remains limited unless the MOF material is transferred to a carbon-based material through heat treatment. To overcome this limitation, we employed coordination engineering to incorporate hexaaminotriphenylene (HATP) molecules with strong conjugation into Co-MOF-74. The resulting Co-MOF-74-HATP catalyst represents high activity, achieving an ORR half-wave potential (E_1/2) of 0.84 V and demonstrating good stability (ΔE_1/2 = 20 mV after 10,000 cycles). Additionally, the Co-MOF-74-HATP also performs a 320 mV overpotential (10 mA·cm⁻²) for the oxygen evolution reaction. Meanwhile, Co-MOF-74-HATP displays a peak power density of 96.6 mW·cm⁻² in zinc-air batteries, surpassing the commercially available Pt/C + RuO₂. This work presents a new pathway to design MOF-based ORR catalysts and provides a new direction for the preparation of key materials for zinc-air battery (ZAB).