FeNi-Based Coordination Crystal Directly Serving as Efficient Oxygen Evolution Reaction Catalyst and Its Density Functional Theory Insight on the Active Site Change Mechanism.

Although most metal-organic coordination materials are promising materials used as templates to develop highly efficient electrocatalysts via pyrolysis in situ, few studies have explored the use of these materials for direct catalysis of oxygen evolution reaction (OER). Herein, inspired by the natural synthesis and the inherent properties of metal-organic coordination materials, the FeNi-tannic acid coordination crystal was in situ grown on Ni foam ((FeNi)-Tan/NF) to directly catalyze the OER. It was found that (FeNi)-Tan/NF exhibited predominant OER activity, which required a low overpotential of 208 mV to reach a current density of 50 mA·cm under a small Tafel slope of 33.5 mV·dec, and it possessed robust stability. Density functional theory (DFT) calculations demonstrated that the active site change from Ni in Ni-Tan to the Fe atom in (FeNi)-Tan may provide a more favorable OER catalytic route. This application of such polyphenol coordination materials is promising for stimulating the exploration of functional metal-organic coordination materials toward applications in the energy conversion field.