Enhanced Electrocatalytic Oxygen Evolution by In Situ Growth of Tetrametallic Metal–Organic Framework Electrocatalyst FeCoNiMn-MOF on Nickel Foam

Developing highly efficient, cost-effective, non-noble-metal-based electrocatalysts with superior performance and stability for oxygen evolution reactions is of immense challenge as well as great importance for the upcoming sustainable and green energy conversion technologies. The multivariate metal-organic frameworks with hierarchical porous structures and unsaturated coordination modes are considered to be promising emerging energy materials. In this work, a series of multimetallic MOFs were directly grown on nickel foam (NF) through the solvothermal method. Notably, the optimized tetrametallic FeCoNiMn-MOF/NF shows a low overpotential of 239 mV to achieve a current density of 50 mA cm^-2 with a Tafel slope of 62.05 mV dec^-1 for OER in 1 M KOH. It also exhibits excellent stability and durability over 100 h in chronoamperometric studies. The enhanced performance is closely tied to the high activity of iron and nickel ions and the decomposed and reconstructed Ni/Fe-OOH intermediates of the FeCoNiMn-MOF/NF during the OER process, which are revealed by XPS analysis and in situ Raman spectroscopy. This present work demonstrates the feasibility and advantage of utilizing highly efficient and durable multimetallic MOFs for electrocatalytic oxygen evolution.