Boosting Electrocatalytic Activity of Bimetallic CoNi‐MOF for OER and HER Through a Synergistic Bimetallic Approach

Three new isostructural Co(II), Ni(II), and CoNi metal‐organic frameworks (MOFs) were designed and synthesized as efficient electrocatalysts using the bis‐coordinating ligand 3‐pyridyl acrylic acid. Structural analysis revealed that all three MOFs exhibit a three‐dimensional structure with similar cell parameters. The electrocatalytic activities toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) were systematically investigated. Notably, the bimetallic CoNi‐MOF demonstrated significantly greater activity towards OER and HER compared to its monometallic counterparts, Co‐MOF and Ni‐MOF. For OER, CoNi‐MOF requires an overpotential of 350 mV to achieve a 10 mA cm−2 current density, which is close to that of the state‐of‐the‐art catalyst RuO₂, which requires a 320 mV overpotential to attain the same current density. For HER, CoNi‐MOF demands an overpotential of 150 mV to reach the 10 mA cm−2 in a 1 M KOH solution. Moreover, the electrocatalyst exhibited excellent stability for 6 hours and 1000 OER cycles, demonstrating its superiority in these reactions. The significant enhancement in the performance of CoNi‐MOF is attributed to the bimetallic synergistic effects between the redox‐active metal centers Co²⁺ and Ni²⁺, which increase the activity of catalyst's surface, resulting in enhanced current density and reduced overpotential.