Unveiling Chemically Robust Bimetallic Squarate-Based Metal–Organic Frameworks for Electrocatalytic Oxygen Evolution Reaction

Here, this work reports an innovative strategy for the synthesis of chemically robust metal–organic frameworks (MOFs), and applies them as catalysts for the electrocatalytic oxygen evolution reaction (OER). A bimetallic squarate-based MOF (Sq-MOF) with a zbr topology serves as an excellent platform for electrocatalytic OER owing to its open porous structure, high affinity toward water, and presence of catalytically active 1D metal hydroxide strips. By regulating the Ni2+ content in a bimetallic squarate MOF system, the electrochemical structural stability toward OER can be improved. The screening of various metal ratios demonstrates that Ni3Fe1 and Ni2Fe1 Sq-zbr-MOFs show the best performance for electrocatalytic OER in terms of catalytic activity and structural stability. Ni2Fe1 Sq-zbr-MOF shows a low overpotential of 230 mV (at 10 mA cm−2) and a small Tafel slope of 37.7 mV dec−1, with an excellent long-term electrochemical stability for the OER. Remarkably, these overpotential values of Ni2Fe1 Sq-zbr-MOF are comparable with those of the best-performing layered double hydroxide (LDH) systems and outperforms the commercially available noble-metal-based RuO2 catalyst for OER under identical operational conditions.