Methanol Oxidation on Pt3Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition

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• 作者：Xiaoqing Lu ; Zhigang Deng ; Chen Guo ; Weili Wang ; Shuxian Wei ; Siu-Pang Ng ; Xiangfeng Chen ; Ning Ding ; Wenyue Guo ; Chi-Man Lawrence Wu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：May 18, 2016
• 年：2016
• 卷：8
• 期：19
• 页码：12194-12204
• 全文大小：579K
• 年卷期：0
• ISSN：1944-8252

文摘

PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt₃Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CH_xOH_y, x = 1–3, y = 0–1) were strongly adsorbed and preferred decomposition rather than desorption on Pt₃Sn(111). The competitive methanol decomposition started with the initial O–H bond scission followed by successive C–H bond scissions, (i.e., CH₃OH → CH₃O → CH₂O → CHO → CO). The Brønsted–Evans–Polanyi relations and energy barrier decomposition analyses identified the C–H and O–H bond scissions as being more competitive than the C–O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt₃Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.