Precisely Applying TiO2 Overcoat on Supported Au Catalysts Using Atomic Layer Deposition for Understanding the Reaction Mechanism and Improved Activity in CO Oxidation

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• 作者：Chunlei Wang ; Hengwei Wang ; Qi Yao ; Huan Yan ; Junjie Li ; Junling Lu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：January 14, 2016
• 年：2016
• 卷：120
• 期：1
• 页码：478-486
• 全文大小：559K
• ISSN：1932-7455

文摘

For TiO₂ supported Au catalysts, the Au particle size and the interfacial perimeter sites between Au particles and the TiO₂ support both play important roles in CO oxidation reaction. However, changing the Au particle size inevitably accompanied by the change of the perimeter length makes it extremely difficult to identify their individual roles. Here we reported a new strategy to isolate them by applying TiO₂ overcoat to Au/Al₂O₃ and Au/SiO₂ catalysts using atomic layer deposition (ALD) where the new Au–TiO₂ interfacial length was precisely tuned to different degrees while preserving the particle size. High resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements of CO chemisorption all confirmed that the TiO₂ overcoat preferentially decorates the low-coordinated sites of Au nanoparticles and generates Au–TiO₂ interfaces. In CO oxidation, we demonstrated a remarkable improvement of the catalytic activities of Au/Al₂O₃ and Au/SiO₂ catalysts by the ALD TiO₂ overcoat. More interestingly, the activity as a function of TiO₂ ALD cycles obviously showed a volcano-like behavior, providing direct evidence that the catalytic activities of TiO₂ overcoated Au catalysts strongly correlate with the total length of perimeter sites. Finally, our work suggests that this strategy might be a new method for atomic level understanding the reaction mechanism and high performance catalyst design.