Structural and Compositional Optimization of Fe–Co–Ni Ternary Amorphous Electrocatalysts for Efficient Oxygen Evolution in Anion Exchange Membrane Water Electrolysis

Anion exchange membrane water electrolysis (AEMWE) offers a sustainable path for hydrogen production with advantages such as high current density, dynamic responsiveness, and low-cost electrocatalysts. However, the development of efficient and durable oxygen evolution reaction (OER) electrocatalysts under operating conditions is crucial for achieving the AEMWE. This study systematically investigated Fe-Co-Ni ternary amorphous electrocatalysts for the OER in AEMWE through a comprehensive material library system comprising 21 composition series. The study aims to explore the relationship between composition, degree of crystallinity, and electrocatalytic activity using ternary contours and binary plots to derive optimal catalysts. The findings reveal that higher Co and lower Fe contents lead to increased structural disorder within the Fe-Co-Ni system, whereas an appropriate amount of Fe addition is necessary for OER activity. It is concluded that the amorphous structure of Fe-Co₃-Ni possesses an optimal ternary composition and degree of crystallinity to facilitate the OER. Post-OER analyses reveal that the optimized ternary amorphous structure induces structural reconstruction into an OER-favorable OOH-rich surface. The Fe-Co₃-Ni electrocatalysts exhibit outstanding performances in both half-cells and single-cells, with an overpotential of 256 mV at 10 mA cm^{- 2} and a current density of 2.0 A cm^{- 2} at 1.89 V, respectively.