Core鈭扴hell Phase Separation and Structural Transformation of Pt3Sn Alloy Nanoparticles Supported on 纬-Al2O3 in the Reduction and Oxidation Processes Characterized by I

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• 作者：Yohei Uemura ; Yasuhiro Inada ; Kyoko K. Bando ; Takehiko Sasaki ; Naoto Kamiuchi ; Koichi Eguchi ; Akira Yagishita ; Masaharu Nomura ; Mizuki Tada ; Yasuhiro Iwasawa
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 7, 2011
• 年：2011
• 卷：115
• 期：13
• 页码：5823-5833
• 全文大小：1123K
• 年卷期：v.115,no.13(April 7, 2011)
• ISSN：1932-7455

文摘

Unique catalytic capabilities of supported bimetallic nanoparticles with synergistic functions mark them as a significant advancement in catalytic technologies. The dynamic behavior and kinetics of structural change of catalysts in the reduction and oxidation processes are fundamental issues to understand their catalytic properties and performances as well as to regulate the structure and composition in alloy nanoparticles. The core鈭抯hell phase separation and structural transformation of Pt₃Sn alloy nanoparticles on 纬-Al₂O₃ during the reduction and oxidation processes were characterized by in situ time-resolved energy-dispersive XAFS (DXAFS) and quick XAFS (QXAFS) techniques. The time-resolved XAFS techniques provided the kinetics of the change in structures and oxidation states of the bimetallic nanoparticle catalyst. The oxidation of Pt₃Sn nanoparticles on 纬-Al₂O₃ with O₂ at 673 K proceeded by three successive steps via two intermediates to form PtO core nanoparticles with SnO₂ shells, whereas the reduction of the oxidized nanoparticles with H₂ at 673 K proceeded as a single process with similar rate constants at Pt and Sn sites. The kinetic parameters and mechanisms for the reduction and oxidation of the Pt₃Sn/纬-Al₂O₃ catalyst were determined by the time-resolved XAFS techniques.