Surface-Driven Electron Localization and Defect Heterogeneity in Ceria

作者：Xingfan Zhang, Akira Yoko, Yi Zhou, W.S.S. Jee, Álvaro Mayoral, Taifeng Liu, Jingcheng Guan, You Lü, Thomas W. Keal, John Buckeridge, Kakeru Ninomiya, Maiko Nishibori, Susumu Yamamoto, Iwao Matsuda, Tadafumi Adschiri, Osamu Terasaki, Scott M. Woodley, C. Richard A. Catlow, Alexey A. Sokol · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c10679 · 被引用次数：33 · 研究领域：Catalytic Processes in Materials Science、Electronic and Structural Properties of Oxides、Copper-based nanomaterials and applications

High Resolution Image Download MS PowerPoint Slide The exceptional performance of ceria (CeO 2 ) in catalysis and energy conversion is fundamentally governed by its defect chemistry, particularly oxygen vacancies. The formation of each oxygen vacancy (V O •• ) is assumed to be compensated by two localized electrons on cations (Ce 3+ ). Here, we show by combining theory with experiment that while this 1 V O ••: 2Ce 3+ ratio accounts for the global charge compensation, it does not apply at the local scale, particularly in nanoparticles. Hybrid quantum mechanical/molecular mechanical (QM/MM) defect calculations, together with synchrotron X-ray photoelectron spectroscopy (XPS) measurements, show that electrons have a strong preference to localize and segregate on surfaces, which can overcome the trapping force from the V O •• sites in the bulk. At a given Fermi level, the surface V O •• tends to trap more electrons than those in bulk, resulting in a higher Ce 3+ to V O •• ratio on surfaces than that in the bulk, driven by the preferential localization of electrons and enhanced V O •• –Ce 3+ coupling. Large-scale unbiased Monte Carlo simulations on ceria nanoparticles confirmed this trend and further show that the surface segregation of electrons is more pronounced at low reduction levels and in smaller nanoparticles. In highly reduced ceria nanoparticles, however, the enhanced repulsive interactions lead to a less significant extent of defect heterogeneity or even reverse the loc...