Ce and S Co-Induced Oxygen Vacancies for Enhanced Alkaline Water Electrolysis

Rational regulation of surface reconstruction and defect chemistry is crucial for developing high-performance non-noble-metal electrocatalysts toward the oxygen evolution reaction (OER). Herein, a Ce- and S-co-induced oxygen-vacancy strategy is developed to construct an ultrathin NiCeS nanosheet array grown in situ on nickel foam (NiCeS/NF) via a molten-salt route. Structural analyses reveal that NiCeS/NF features a multiphase Ni–Ce–S framework composed of sulfide, oxysulfide, and sulfate species, together with abundant heterointerfaces and defect-rich surface environments. Spectroscopic studies demonstrate that the synergistic coupling of Ce and S effectively redistributes the local electronic structure of Ni sites, enriches oxygen-deficient species, and accelerates electrochemical surface reconstruction into the active oxyhydroxide phase. Benefiting from the integrated structural and electronic modulation, NiCeS/NF exhibits outstanding OER performance in alkaline media, delivering a low overpotential of 187 mV at 10 mA cm ^− 2 , a small Tafel slope of 44.1 mV dec ^− 1 , and robust durability at 1000 mA cm ^− 2 for ≈ 400 h. This work provides an effective defect/interfacial engineering strategy for promoting alkaline water oxidation and offers insight into the cooperative role of rare-earth and sulfur species in reconstructive electrocatalysis.