Graphene-Supported Ir-Doped FeCoNiO _<i>x</i> Nanosheets for Efficient Oxygen Evolution Electrocatalysis

Developing inexpensive electrocatalysts with high performance to replace precious metal benchmarks (e.g., IrO2 and RuO2) for the oxygen evolution reaction (OER) is crucial for sustainable hydrogen production. Although FeCoNi-based oxygen/hydroxides are promising in this regard, their application is limited by their stability, scalability, and suboptimal activity. Herein, we synthesized graphene-supported Ir-doped FeCoNiOx nanosheets (Ir/FeCoNiOx@G) via a one-step liquid-phase coprecipitation method. Ir doping induced compressive lattice strain and modulated charge distribution, optimizing the electronic structure and creating high-energy distortion sites. Meanwhile, graphene enhanced the conductivity, dispersion, and surface area. The resulting electrocatalysts required ultralow overpotentials of 214 and 268 mV to achieve specific current densities of 10 and 100 mA cm–2 in 1 M KOH, respectively, surpassing controls and commercial IrO2. It exhibited favorable kinetics, low charge transfer resistance, high intrinsic activity, and outstanding stability (>50 h at 10 mA cm–2). Characterization confirmed that Ir doping facilitated oxygen vacancies, strengthened metal–oxygen bonds, and enabled a stable high-valent oxyhydroxide surface in the OER. This work demonstrates a synergistic doping and support strategy for designing highly active and durable OER electrocatalysts.