Ligand-engineered in situ co-growth of MOF-74/Ni(OH)₂ on nickel foam for enhanced oxygen evolution electrocatalysis

The oxygen evolution reaction (OER) is the rate-determining step in water electrolysis, and the development of high-performance Earth-abundant electrocatalysts remains challenging. Here, we report a novel GA-mediated ligand-engineering strategy to direct the in situ co-growth of MOF-74/Ni(OH)₂ on nickel foam in a single hydrothermal step, synchronizing Ni²⁺ dissolution, MOF-74 assembly and Ni(OH)₂ growth, thereby mitigating some limitations associated with conventional post-loading methods. The optimized GA ratio (x = 0.3) yields a hierarchical heterostructure with preserved MOF-74 crystallinity, abundant active sites and modulated electronic structure. MOF-74-GA_0.3/NF exhibits excellent OER performance (206 mV at 10 mA cm^-2, 35.4 mV dec^-1) and 350 h stability, undergoing electrochemical reconstruction into NiOOH/FeOOH species after the OER, which are likely associated with the catalytically active phase. This generalizable strategy provides new mechanistic insights for designing MOF-derived OER electrocatalysts.