Cobalt and Yttrium Doping to Activate Dual-Site Mechanism of Amorphous NiFeOOH for Large-Current Water Electrooxidation

The difference in hydroxyl adsorption between Ni and Fe sites in NiFeOOH limits the efficient dual-site synergistic mechanism (DSSM) during oxygen evolution reaction (OER). Here, a novel needle-array electrodeposition is reported for the scalable and efficient fabrication of Co and Y co-doped NiFeOOH catalyst. It achieves an ultralow overpotential of 270 mV at 1 A cm⁻² with a small Tafel slope of 30.7 mV dec⁻¹. It maintains stable operation at 1 A cm⁻² for 1500 hrs with 98 % initial potential retention. When integrated into a 25 cm² anion exchange membrane electrolyzer, the system only needs 2.13 V to achieve 1 A cm⁻². XPS, XAS, and DFT studies reveal that Co and Y dopants increase the Lewis acidity of Ni sites, enhancing ^*OH adsorption. Concurrently, the incorporation of large Y atoms induces lattice distortion and elongates Fe─O─M bonds, weakening ^*OH binding at Fe sites. This dual-site modulation reduces adsorption disparity, activates NiFe dual-active centers, and promotes the DSSM pathway, as confirmed by in situ ATR-SEIRAS. The rate-determining step energy is lowered to 1.71 eV, significantly outperforming the conventional AEM pathway (2.51 eV). This work provides dual-site modulation into engineering high-performance NiFe-based OER catalysts for practical water electrolysis.