Atomic Cerium Boosts Oxygen Evolution via Electronic Coupling in Defective CoFe-Layered Double Hydroxides
Yangchun Guo, Tingting Wei, Xiaodong Hao, Xuan Zhao, Zhen-Hong He, Qiheng Ma, Zhuangzhuang Hu, Shufang Ma, Xiaoxu Liu, Bingshe XU
Abstract
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 0.2 CoFe-LDH, is thoroughly characterized by atomic-resolution electron microscopy and synchrotron-based X-ray spectroscopy, which confirm the atomic dispersion of Ce 3+ 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 Ce 3+ /Ce 4+ 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.