Dynamic surface sculpting of low-cost NiFe alloy towards efficient oxygen evolution reaction

Nickel‑iron alloys, particularly stainless steel (SS), emerge as promising candidates for alkaline oxygen evolution reaction (OER) catalysts due to their exceptional elemental abundance and low cost. However, their direct application is hampered by the insufficient activity and structural stability of the derived catalytic phases. Here, a “sequential leaching‑induced vacancy engineering” strategy is demonstrated to reconstruct 201 SS into a highly active Fe‑replenished NiFeOOH‑V Cr catalyst (denoted R‑ITE‑201). The formation of R-ITE-201 originates from preferential Cr leaching in the original structure, which induces local lattice reconstruction associated with Cr-vacancy (V Cr) formation and promotes the generation of a Ni/Fe-dominated oxy/hydroxide phase. The performed soft-X-ray absorption spectroscopy (O‑K edge), in-situ Raman spectra and density functional theory provide consistent evidence that Cr removal-induced local reconstruction enhances metal–oxygen covalency and elevates oxidation states of Ni and Fe sites, activating and stabilizing the lattice oxygen‑mediated water oxidation. The R‑ITE‑201 electrode exhibits good OER performance in 6 M KOH, requiring overpotentials of only 249 and 290 mV to reach 100 and 1000 mA cm −2 , respectively. Moreover, an R‑ITE‑201||Raney‑Ni electrode pair operates stably for at least 800 h at 500 mA cm −2 .