Wang Xiyang, Zhang Qinghua, Li Xinbo, Meng Fanqi, Chen Shengru, Chen Zuolong, Cong Yingge, Boyko Teak, Regier Tom, Guo Er-Jia, Xiao Yi, Li Liping, Li Guangshe, Feng Shouhua, Wu Yimin A
Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Materials Interfaces Foundry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
J Am Chem Soc. 2024 Dec 18;146(50):34364-34373. doi: 10.1021/jacs.4c08643. Epub 2024 Oct 23.
Understanding the fundamental effect of the oxygen vacancy atomic structure in perovskite oxides on catalytic properties remains challenging due to diverse facets, surface sites, defects, etc. in traditional powder catalysts and the inherent structural complexity. Through quantitative synthesis of tetrahedral (LaCoO-T), pyramidal (LaCoO-P), and octahedral (LaCoO) epitaxial thin films as model catalysts, we demonstrate the reactivity orders of active-site geometrical configurations in oxygen-deficient perovskites during the CO oxidation model reaction: CoO tetrahedron > CoO octahedron > CoO pyramid. Ambient-pressure Co L-edge and O K-edge XAS spectra clarify the dynamic evolutions of active-site electronic structures during realistic catalytic processes and highlight the important roles of defect geometrical structures. In addition, in situ XAS and resonant inelastic X-ray scattering spectra and density functional theory calculations directly reveal the nature of high reactivity for CoO sites and that the derived shallow-acceptor defect levels in the band structure facilitate the adsorption and activation of reactive gases, resulting in more than 23-fold enhancement for catalytic reaction rates than CoO sites.
