NiFe-based layered double hydroxides (LDHs) are among the most effective oxygen evolution reaction (OER) catalysts, yet their performance is fundamentally constrained by the quantity-quality paradox: the trade-off between active site density and intrinsic activity. Herein, we leverage a sacrificial Cr 3+ -triggered cascade reconstruction to modulate the surface Fe/Ni stoichiometry and unveil a high density of Ni active centers. Driven by its local environment, the preferential dissolution of Cr 3+ during electrochemical activation yields a transient CrO 4 2- -enriched interfacial layer, thereby inducing selective Fe leaching and regulating the local bonding environment to promote Ni oxidation. This cascade evolution effectively modulates the surface Fe/Ni stoichiometry, thereby expanding the population of Ni centers and stabilizing high-valent Ni 3+ species with enhanced intrinsic kinetics. As a result, a cation-vacancy-rich NiFeOOH@NiFe LDH heterointerface is spontaneously constructed with optimized electronic structure and favorable reaction energetics. Compared to the undoped sample, the Cr-modified catalyst exhibits significantly enhanced OER kinetics and robust electrochemical durability. Density functional theory calculations further elucidate the origins of the enhanced activity, confirming that the reconstructed heterointerface significantly mitigates the kinetic barriers for the rate-determining steps. This study elucidates a sacrificial-ion-mediated reconstruction pathway, offering a general strategy for designing high-performance OER.
Wan et al. (Mon,) studied this question.