Highly Stable Bimetallic AuIr/TiO2 Catalyst: Physical Origins of the Intrinsic High Stability against Sintering

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• 作者：Chang Wan Han ; Paulami Majumdar ; Ernesto E. Marinero ; Antonio Aguilar-Tapia ; Rodolfo Zanella ; Jeffrey Greeley ; Volkan Ortalan
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：15
• 期：12
• 页码：8141-8147
• 全文大小：442K
• ISSN：1530-6992

文摘

It has been a long-lived research topic in the field of heterogeneous catalysts to find a way of stabilizing supported gold catalyst against sintering. Herein, we report highly stable AuIr bimetallic nanoparticles on TiO₂ synthesized by sequential deposition-precipitation. To reveal the physical origin of the high stability of AuIr/TiO₂, we used aberration-corrected scanning transmission electron microscopy (STEM), STEM-tomography, and density functional theory (DFT) calculations. Three-dimensional structures of AuIr/TiO₂ obtained by STEM-tomography indicate that AuIr nanoparticles on TiO₂ have intrinsically lower free energy and less driving force for sintering than Au nanoparticles. DFT calculations on segregation behavior of AuIr slabs on TiO₂ showed that the presence of Ir near the TiO₂ surface increases the adhesion energy of the bimetallic slabs to the TiO₂ and the attractive interactions between Ir and TiO₂ lead to higher stability of AuIr nanoparticles as compared to Au nanoparticles.