Enhancing activity and stability of bimetallic metal-organic frameworks (MOFs) for overall electrochemical water splitting through nanocomposite formation

Designing efficient, cost-effective, and stable earth-abundant metal electrocatalysts is imperative for the large-scale production and commercialization of green hydrogen technologies based on water electrolysis. Multivariate metal-organic frameworks (MOFs), in this regard, have emerged as promising candidates due to their uniform active sites, tuneable structures, and high surface area . However, they typically suffer from low stability under harsh chemical conditions prevalent in alkaline water electrolyzers. Here, we report that combining bimetallic MOFs based on Fe and Ni (FeNi-MOF) with layered double hydroxides (LDHs) not only improves their catalytic activity but also significantly enhances their stability. We propose that synergic interaction between FeNi-MOF and NiMo-LDH tunes the composite's chemical and electronic structure, enhancing water adsorption and dissociation. The optimized nanocomposite showed outstanding electrocatalytic activities for water splitting in 1 M KOH, requiring low overpotentials of 160 mV and 237 mV to attain a 10 mA cm −2 current density for Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER), respectively. The integrated two-electrode system utilizing FeNi-MOF@NiMo-LDH bifunctional electrocatalysts required only 1.62 V potential at 10 mA cm −2 with an excellent durability of 50 h. This electrochemical performance surpasses most of the recently reported MOF-based electrocatalysts . • A composite of a bimetallic metal-organic framework (MOF) and a layered double hydroxide (LDH) shows enhanced activity for overall water splitting. • The composite shows high stability and Faraday efficiency. • LDH is believed to contribute to the enhanced stability and activity of the MOF. Synopsis: Composite materials of bimetallic metal-organic frameworks with layered double hydroxide provide stable and efficient electrocatalysts for overall water splitting.