Oxygen-vacancy-rich Ni/NiO transition layer promotes interfacial coupling and reconstruction of NiFe LDH for efficient oxygen evolution reaction

Long-term stable and efficient oxygen evolution reaction (OER) remains a major challenge for alkaline water electrolysis due to catalyst detachment under vigorous bubble evolution, chemical dissolution, and sluggish reconstruction into the true active phase. To address these challenges, we construct an oxygen-vacancy (V O )-rich Ni/NiO transition layer on nickel foam, which simultaneously strengthens the interfacial coupling with electrodeposited NiFe layered double hydroxide (LDH), regulates its electronic structure, and suppresses catalyst detachment during vigorous gas evolution. The transition layer enables stable growth and robust anchoring of NiFe LDH, effectively suppressing catalyst detachment during long-term operation and enabling negligible activity decay over 900 h at 500 mA cm −2 . Meanwhile, without direct compositional modification of NiFe LDH, the V O -rich Ni/NiO transition layer optimizes its local electronic environment, promotes the oxidation of Ni 2+ to highly active Ni 3+ species, and accelerates the reconstruction of NiFe LDH into the dominant active NiFeOOH phase during OER. Benefiting from these synergistic effects, the as-prepared electrode delivers low overpotentials of 230 mV, 268 mV, and 303 mV at 10 mA cm −2 , 100 mA cm −2 , and 500 mA cm −2 , respectively, together with a small Tafel slope of 54.2 mV dec −1 . This work offers a simple and effective strategy to simultaneously achieve strong catalyst adhesion and promote active-phase reconstruction, demonstrating considerable potential for industrial OER applications.