Electrocatalytic performance optimization of Co-MOF-74 and IrO₂ hybrid catalysts for acidic oxygen evolution reaction

Proton exchange membrane water electrolysis (PEMWE) is a promising route for low-carbon hydrogen production, but its practical efficiency is limited by the sluggish oxygen evolution reaction (OER) kinetics under acidic conditions. Although IrO₂ remains the state-of-the-art acidic OER catalyst, its high cost and scarcity motivate strategies that reduce noble-metal loading without compromising performance. Here, we report a simple and scalable hybrid electrocatalyst prepared by physically blending solvothermally synthesized Co-MOF-74 (constructed from cobalt nodes and 2,5-dihydroxyterephthalic linkers) with commercial IrO₂ across a range of controlled mass ratios. Electrochemical testing in 1 M H₂SO₄ reveals strong composition-dependent OER activity, with an optimized 40 wt% Co-MOF/60 wt% IrO₂ composite achieving an overpotential of 294 mV at 10 mA cm^{− 2} and maintaining stable operation at this current density for 7 h under chronopotentiometric conditions. Structural analysis reveals that IrO₂ nanoparticles are uniformly dispersed across the porous Co-MOF framework, increasing the accessibility of catalytic sites and mitigating IrO₂ agglomeration. Overall, this work demonstrates that a straightforward MOF/oxide physical hybridization approach can effectively lower Ir content while preserving acidic OER activity, offering a practical and cost-effective design pathway for anode catalysts in PEMWE.