Dissociative Adsorption of Methane on Surface Oxide Structures of Pd−Pt Alloys

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• 作者：Arezoo Dianat ; Nicola Seriani ; Lucio Colombi Ciacchi ; Wolfgang Pompe ; Gianaurelio Cuniberti ; Manfred Bobeth
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：December 17, 2009
• 年：2009
• 卷：113
• 期：50
• 页码：21097-21105
• 全文大小：360K
• 年卷期：v.113,no.50(December 17, 2009)
• ISSN：1932-7455

文摘

The dissociative adsorption of methane on variously oxidized Pd, Pt, and Pd−Pt surfaces is investigated using density functional theory as a step toward understanding the combustion of methane on these materials. For Pd−Pt alloys, models of surface oxide structures are built on the basis of known oxides on Pd and Pt. The methane adsorption energy presents large variations depending on the oxide structure and composition. Adsorption is endothermic on the bare Pd(111) metal surface as well as on stable thin layer oxide structures such as the (√5 × √5) surface oxide on Pd(100) and the PtO₂-like oxide on Pt(111). Instead, large adsorption energies are obtained for the (100) surface of bulk PdO, for metastable mixed Pd_1−xPt_xO_4/3 oxide layers on Pt(100), and for Pd−Pt(111) surfaces covered with one oxygen monolayer. In the latter case, we find a net thermodynamic preference for a direct conversion of methane to methanol, which remains adsorbed on the oxidized metal substrates via weak hydrogen-bond interactions.