Rational Yttrium Doping for Exceptional Oxygen Evolution Activity and Durability in Nickel–Iron Phosphide Electrocatalysts

Earth-abundant nickel–iron phosphides (NiFeP) struggle to achieve the dual requirements of high catalytic activity and long-term stability needed for practical water-electrolysis-based hydrogen production. Herein, we overcome this fundamental activity–stability trade-off through the incorporation of yttrium (Y). The resulting Y-doped NiFeP catalyst exhibits extraordinary performance, requiring only 129 mV and 170 mV (iR-corrected) overpotential to deliver current densities of 10 and 100 mA cm–2, respectively, representing a 90 mV enhancement over pristine NiFeP and surpassing benchmark RuO2 by 172 mV. Remarkably, the catalyst demonstrates unprecedented durability, sustaining >530 mA cm–2 for 50 h and operating steadily for over 172 h at 100 mA cm–2 under alkaline conditions. Through comprehensive characterization techniques coupled with density functional theory (DFT) calculations, we elucidate that Y doping induces a bidirectional electron redistribution that depletes charge from Ni centers while enriching Fe sites, thereby cooperatively optimizing the intermediate adsorption and significantly reducing the energy barrier of the potential-determining step (PDS). Concurrently, Y acts as a structural stabilizer, preferentially preserving the conductive Ni2P crystalline phase during prolonged anodic operation while suppressing detrimental phase transformations. This work establishes yttrium as a versatile promoter and offers a rational design principle for engineering high-performance, rare-earth-modified electrocatalysts toward practical water splitting.