The Beneficial Role of the Cometals Pd and Au in the Carbon-Supported PtPdAu Catalyst Toward Promoting Ethanol Oxidation Kinetics in Alkaline Fuel Cells: Temperature Effect and Reaction Mechanism
The Beneficial Role of the Cometals Pd and Au in the Carbon-Supported PtPdAu Catalyst Toward Promoting Ethanol Oxidation Kinetics in Alkaline Fuel Cells: Temperature Effect and Reaction Mechanism
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DOI：
10.1021/jp200318m
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发表时间：
2011-08-11
影响因子：
3.7
通讯作者：
Mukherjee, Sanjeev
中科院分区：
文献类型：
--
作者：
Datta, Jayati;Dutta, Abhijit;Mukherjee, Sanjeev
在20-80℃温度范围内，用电化学方法研究了乙醇在碳载三元合金催化剂上的氧化动力学。为了更好地了解各金属组分对乙醇催化氧化的贡献，一些研究扩展到单个贵金属上进行比较，但在单一温度下(20℃)。与合金催化剂相比，单独的金属几乎不能显示出它们对乙醇氧化的催化效率。三元催化剂具有较低的乙醇氧化起始电位和较大的温度依赖性。随着电位的升高，乙醇在铂碳电极上氧化的表观活化能(E-a(App))增大，而在Pt30Pd38Au32/C电极上乙醇氧化的表观活化能(E-a(App))有减小的趋势。结果表明，在所研究的温度范围内，Pt30Pd38Au32/C电极对乙醇残留物具有良好的耐受性。与上述研究的结果相关联，试图阐明氧化反应机理，这进一步引起了将工作扩展到通过离子色谱分析来估计在相同温度范围内乙醇氧化生成的产物的兴趣。与单一铂相比，在三元催化剂上得到的氧化产物(如醋酸盐和碳酸盐)的数量显著增加，证实了乙醇氧化的动力学增强，这归因于Pd和Au在铂基质中形成的共金属伙伴关系。综上所述，多金属纳米晶不仅能够在碱性溶液中从乙醇燃料中提取尽可能多的电子，利用更多的能量，而且还可以通过在相当大程度上降低铂含量来降低催化剂材料的成本。
Electrochemical investigations have been carried out to study the oxidation kinetics of ethanol in alkaline solution on carbon-supported ternary alloy catalysts Pt-Pd-Au within the temperature range of 20-80 degrees C. To derive a better understanding of the contribution of each of the metallic components toward the catalytic oxidation of ethanol, some of the investigations were extended to the individual noble metals for comparison, however, at a single temperature (20 degrees C). The individual metals could barely show their catalytic efficiency toward ethanol oxidations when compared to the alloyed catalyst. The ternary catalyst exhibited much lower values and a larger temperature dependence of onset potential for ethanol oxidation. With the rise of potential, the apparent activation energy (E-a(app)) for ethanol oxidation on the Pt/C electrode increased, whereas a decreasing trend was observed with the Pt30Pd38Au32/C electrode. It was suggested that the Pt30Pd38Au32/C electrode bears an excellent tolerance toward ethanolic residues, for the temperature range studied. In correlation with the results obtained from the above study, attempts were made to elucidate the oxidation reaction mechanism, and this further evoked interest in extending the work to the estimation of products formed during oxidation of ethanol within the same temperature range through ion chromatographic analysis. The pronounced increase in the quantity of oxidation products, such as acetate and carbonate, obtained over the ternary catalyst as compared to single Pt, substantiates the kinetic enhancement of ethanol oxidation, attributable to the cometal partnership between Pd and Au when incorporated in the Pt matrix. In summary, the multimetallic nanocrystallites can not only show their capability of extracting the best possible number of electrons from the alcohol fuel in alkaline solutions, harnessing more energy, but also, at the same time, bring down the cost of the catalyst material by reducing the Pt content to a considerable extent.