Breaking Linear Scaling via Lattice-Strained Ce-Doped NiFe Nanocrystals: From Mechanism Activation to Cell-Level Alkaline Water Electrolysis
Feifei Li, Luyu Yang, Qin Li, Tong Sun, Jinke Shen, X.P. Wang, Zijian Gao, Sihao Deng, Jim P. Zheng, Cunman Zhang, L. J. Jin
Abstract
Overcoming the intrinsic linear scaling relationship that governs intermediate adsorption energies in oxygen evolution reaction (OER) electrocatalysis is crucial for unlocking higher catalytic efficiency beyond the limitations of the conventional adsorbate evolution mechanism (AEM). Here, we propose a lattice-engineering strategy to activate the oxide path mechanism (OPM)─a distinct reaction pathway that circumvents high-energy *OOH intermediates─by incorporating trace amounts of Ce into NiFe through a one-step electrodeposition process. The introduction of Ce induces pronounced lattice strain and abundant grain boundaries, shortening the Ni–Ni interatomic distance from 2.12 to 1.94 Å and constructing dual-metal site geometries that favor direct O–O coupling. This structural transformation not only increases the density of catalytically active sites but also triggers a pathway shift from AEM to OPM, thereby circumventing linear scaling constraints and enhancing intrinsic activity. Consequently, the NiFe-Ce/CeO 2 -0.01 catalyst exhibits an ultralow overpotential of 135 mV at 10 mA cm –2 and 332 mV at 500 mA cm –2, along with an operational lifetime exceeding 1000 h. When integrated into an alkaline water electrolyzer, the system delivers a current density of 1000 mA cm –2 at 1.71 V and maintains robust operation for over 850 h. This study establishes a direct structural–mechanistic correlation between lattice compression and OPM activation, offering a viable strategy to transcend linear scaling limitations and guiding the development of next-generation high-performance OER electrocatalysts.