Oxidized noble metal catalysts are widely used catalysts in heterogeneous catalysts. The strong interaction between metals and carriers, as well as surface defects on carriers, are often considered key factors for the anchoring of precious metal atoms on the surface of reducible oxides (TiO2, CeO2) carriers. He Hong, an academician from the Institute of Urban Environment of the Chinese Academy of Sciences, proposed a new anchoring mechanism for noble metal monoatoms on reducible oxide carriers, in conjunction with Ning Ping and Li Kai from Kunming University of Technology, Zeng Xiaocheng from City University of Hong Kong, and Joseph S. Francisco from the University of Pennsylvania. This mechanism is that the terminal hydroxyl groups on the crystal plane of CeO2 nanocubes (100) serve as direct anchoring points for single atoms of precious metals (Pt, Pd, Ag), rather than surface defects as traditionally believed.
This study used three different morphologies of CeO2 nanomaterials as carriers and loaded Ag. Characterization such as aberration electron microscopy and X-ray absorption fine structure spectroscopy have shown that Ag species only exhibit single atom dispersion on the surface of CeO2 nanocube. Furthermore, research was conducted to construct CeO2 nanocubes rich in defects and hydroxyl groups, and it was found that Ag is more easily dispersed on the hydroxyl rich CeO2 nanocubes. This indicates that surface hydroxyl groups are the direct anchoring points of Ag. Theoretical calculations confirm that the terminal hydroxyl groups on the CeO2-NC (100) crystal plane can form a stable "dumbbell" structure with precious metal atoms, thereby anchoring single atom Ag. This anchoring mechanism has universality and can be applied to precious metal atoms such as Pt and Pd. This achievement reveals the essence of the active center of single atom catalysts, providing new ideas for the design and preparation of efficient and low consumption single atom catalysts.
The relevant research results are titled "Identification of Direct Anchoring Sites for Monoatomic Dispersion of Precious Metals (Pt, Pd, Ag) on CeO2 Support" and published in the German Journal of Applied Chemistry. The research work was supported by the National Natural Science Foundation of China and the Youth Innovation Promotion Association of the Chinese Academy of Sciences.
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