Atomic Cerium Boosts Oxygen Evolution via Electronic Coupling in Defective CoFe-Layered Double Hydroxides

The development of efficient and durable nonprecious electrocatalysts for the oxygen evolution reaction (OER) is critical for sustainable hydrogen production. In this study, a defective CoFe-layered double hydroxide (LDH) support is engineered to stabilize isolated cerium atoms via a facile one-step coprecipitation approach. The resulting single-atom catalyst, denoted Ce_0.2CoFe-LDH, is thoroughly characterized by atomic-resolution electron microscopy and synchrotron-based X-ray spectroscopy, which confirm the atomic dispersion of Ce³⁺ species anchored at cation vacancy sites within the LDH matrix. A strong electronic interaction between Ce and Co/Fe sites is observed, leading to charge redistribution that increases the valence states of transition metals and activates dynamic Ce³⁺/Ce⁴⁺ redox cycling. The optimized catalyst exhibits outstanding OER performance in alkaline media, achieving an overpotential as low as 227 mV at 10 mA·cm^-2, a Tafel slope of 48.3 mV·dec^-1, and excellent stability over 50 h of continuous operation. Electrochemical measurements indicate facilitated charge transfer and an increased electrochemically active surface area. First-principles calculations further reveal that Ce atoms occupying Co vacancies significantly optimize the adsorption of reaction intermediates, reduce the energy barrier of the rate-determining step to 1.81 eV, and induce metallic character through an upshift of the d-band center. This work establishes defect-driven single-atom anchoring as an effective strategy for electronic structure modulation and reaction pathway optimization in LDH-based electrocatalysts, offering valuable insights for the design of high-performance energy conversion materials.