Role of the Three-Phase Boundary of the Platinum–Support Interface in Catalysis: A Model Catalyst Kinetic Study

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• 作者：Evangelos I. Papaioannou ; Christoph Bachmann ; Jonas J. Neumeier ; Daniel Frankel ; Herbert Over ; Juergen Janek ; Ian S. Metcalfe
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：September 2, 2016
• 年：2016
• 卷：6
• 期：9
• 页码：5865-5872
• 全文大小：415K
• 年卷期：0
• ISSN：2155-5435

文摘

A series of microstructured, supported platinum (Pt) catalyst films (supported on single-crystal yttria-stabilized zirconia) and an appropriate Pt catalyst reference system (supported on single-crystal alumina) were fabricated using pulsed laser deposition and ion-beam etching. The thin films exhibit area-specific lengths of the three-phase boundary (length of three-phase boundary between the Pt, support, and gas phase divided by the superficial area of the sample) that vary over 4 orders of magnitude from 4.5 × 10² to 4.9 × 10⁶ m m^–2, equivalent to structural length scales of 0.2 μm to approximately 9000 μm. The catalyst films have been characterized using X-ray diffraction, atomic force microscopy, high-resolution scanning electron microscopy, and catalytic activity tests employing the carbon monoxide oxidation reaction. When Pt is supported on yttria-stabilized zirconia, the reaction rate clearly depends upon the area-specific length of the three-phase boundary, l(tpb). A similar relationship is not observed when Pt is supported on alumina. We suggest that the presence of the three-phase boundary provides an extra channel of oxygen supply to the Pt through diffusion in or on the yttria-stabilized zirconia support coupled with surface diffusion across the Pt.