Nanoclusters of Metal–Organic Frameworks on NiO Nanosheets for Water Splitting

We demonstrate a metal–organic framework (MOF)-assisted electrochemical approach to engineer iron nanoclusters anchored on nickel oxide nanosheets (MOF-Fe NC|NiO NS), creating well-defined heterointerfaces that enable precise electronic modulation and highly active tri-junction catalytic sites. The as-developed MOF-Fe NC|NiO NS electrode exhibits exceptional bifunctional activity, requiring overpotentials (η) of only ∼280 mV for the oxygen evolution reaction (OER) and ∼202 mV for the hydrogen evolution reaction (HER) to attain 10 mA cm –2 in 1.0 M KOH, along with favorable electrochemical intrinsic characteristics and remarkable operational durability (250 h). The MOF-Fe NC|NiO NS||MOF-Fe NC|NiO NS delivers a low cell voltage of 1.67 V at 10 mA cm –2, surpassing benchmark RuO 2 ||Pt/C systems. The superior performance originates from strong Fe–NiO interfacial coupling, which modulates the adsorption energies of H* and OH* intermediates, increases accessible active-site density, accelerates charge-transfer kinetics, and enhances adsorption–desorption processes.