Synthesis, Characterization, and Electrocatalytic Activity toward Methanol Oxidation of Carbon-Supported Ptx−(RuO2−M)1−x Composite Tern

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• 作者：Katlin I. B. Eguiluz ; Geoffroy R. P. Malpass ; Marilia M. S. Pupo ; Giancarlo R. Salazar-Banda ; Luis A. Avaca
• 刊名：Energy & Fuels
• 出版年：2010
• 出版时间：July 15, 2010
• 年：2010
• 卷：24
• 期：7
• 页码：4012-4024
• 全文大小：1297K
• 年卷期：v.24,no.7(July 15, 2010)
• ISSN：1520-5029

文摘

Carbon-supported platinum is commonly used as an anode electrocatalyst in low-temperature fuel cells fueled with methanol. The cost of Pt and the limited world supply are significant barriers for the widespread use of this type of fuel cell. Moreover, Pt used as anode material is readily poisoned by carbon monoxide produced as a byproduct of the alcohol oxidation. Although improvements in the catalytic performance for methanol oxidation were attained using Pt−Ru alloys, the state-of-the-art Pt−Ru catalyst needs further improvement because of relatively low catalytic activity and the high cost of noble Pt and Ru. For these reasons, the development of highly efficient ternary platinum-based catalysts is an important challenge. Thus, various compositions of ternary Ptb>xb>−(RuOb>2b>−M)b>1−xb>/C composites (M = CeOb>2b>, MoOb>3b>, or PbOb>xb>) were developed and further investigated as catalysts for the methanol electro-oxidation reaction. The characterization carried out by X-ray diffraction, energy-dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry point out that the different metallic oxides were successfully deposited on the Pt/C, producing small and well-controlled nanoparticles in the range of 2.8−4.2 nm. Electrochemical experiments demonstrated that the Ptb>0.50b>(RuOb>2b>−CeOb>2b>)b>0.50b>/C composite displays the higher catalytic activity toward the methanol oxidation reaction (lowest onset potential of 207 mV and current densities taken at 450 mV, which are 140 times higher than those at commercial Pt/C), followed by the Ptb>0.75b>(RuOb>2b>−MoOb>3b>)b>0.25b>/C composite. In addition, both of these composites produced low quantities of formic acid and formaldehyde when compared to a commercially available Ptb>0.75b>−Rub>0.25b>/C composite (from E-Tek, Inc.), suggesting that the oxidation of methanol occurs mainly by a pathway that produces COb>2b> forming the intermediary COb>adsb>.