The design and construction of a Co(OH) ₂ @NiFe-MIL/NFF heterostructure catalyst for efficient and ultrastable water oxidation

Metal-organic frameworks (MOFs) are regarded as intriguing candidates for the oxygen evolution reaction (OER) in electrocatalytic water splitting due to their unique intrinsic features. However, the unsatisfactory catalytic activity and stability are the stumbling blocks to practical alkaline water electrolysis application. Herein, a facile strategy is deployed to fabricate a heterostructured electrocatalyst composed of Co(OH)₂ nanosheets and an <i>in situ</i> produced bimetallic MOF (NiFe-MIL) using ferronickel foam (NFF) as both the metal source and the conductive substrate. The hybrid Co(OH)₂@NiFe-MIL/NFF catalyst demonstrates superior OER electrocatalytic activity, achieving a low overpotential of 230 mV (at 10 mA cm^-2), a minimal Tafel slope of 12.79 mV dec^-1, and exceptional long-term stability. The exceptional catalytic activity and stability stem from the synergistic effect of the heterogeneous interfacial structure and multiple active sites. The work establishes a novel paradigm for designing advanced electrocatalysts through rational manipulation of the electronic structure.