Synergistic Effects of Co–N4 and Ni–N4 Sites in 2D Conductive Metal–Organic Framework Electrocatalysts for Enhanced Oxygen Reduction Reaction Performance

Oxygen reduction reaction (ORR) is vital for energy storage and conversion technologies but is hindered by complex multielectron transfer mechanisms and sluggish kinetics. This study explores intrinsically conductive two-dimensional metal–organic frameworks (MOFs), specifically a series of CoxNi3–x(HITP)2 (0 ≤ x ≤ 3) as a model system, enabling precise control over electronic properties and well-defined active site environments. By varying the Co to Ni ratio, we found that a 1:1 ratio enhances the ORR activity significantly. In situ X-ray absorption spectroscopy and density functional theory analyses reveal that Ni–N4 improves conductivity and stability, while Co–N4 provides high-selectivity active sites, offering a robust platform for understanding structure–function relationships in MOF-based and single-atom catalysts.