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

Abstract

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. Optimized GA ratio (x=0.3) yields a hierarchical heterostructure with preserved MOF-74 crystallinity, abundant active sites and modulated electronic structure. MOF-74-GA0.3/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 OER, which are likely associated with the catalytically active phase. This generalizable strategy provides new mechanistic insights for designing MOF-derived OER electrocatalysts.