Alcohol electrooxidation at Pt and Pt–Ru sputtered electrodes under elevated temperature and pressurized conditions
Alcohol electrooxidation at Pt and Pt–Ru sputtered electrodes under elevated temperature and pressurized conditions
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DOI：
10.1016/j.jpowsour.2008.01.011
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发表时间：
2008-05
影响因子：
9.2
通讯作者：
M. Umeda;Hiromasa Sugii;I. Uchida
中科院分区：
文献类型：
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作者：
M. Umeda;Hiromasa Sugii;I. Uchida
研究了甲醇和异丙醇在高温高压条件下的电氧化性能。溅射沉积的Pt和Pt-Ru电极被很好地表征并用于在25-100°C下醇氧化的电化学测量。在600°C下制备的Pt电极具有平坦的表面，并且Pt-Ru形成合金。电化学测量在气密电池中在升高的温度下进行，这伴随着加压条件。这是DAFC升温操作的代表性示例。结果，在25°C下，2-丙醇氧化的起始电位比甲醇氧化的起始电位负约400 mV，并且2-丙醇氧化的电流密度超过甲醇氧化的电流密度。相反，在100°C下，甲醇氧化电流密度超过2-丙醇，并且两者的起始电位几乎相同。在Pt：Ru=50：50的电极上获得甲醇氧化的最高电流密度，而在Pt：Ru=35：65的电极上获得异丙醇氧化的最高电流密度。采用塔菲尔图分析探讨了反应机理。对于甲醇氧化，在速率决定过程中转移的电子数估计为25°C时为1，100°C时为2。这表明甲醇反应机理在25 ° C和100°C下不同。相比之下，在25和100°C下2-丙醇氧化的速率决定过程预计是伴随质子消除反应产生丙酮的1-电子转移。因此，推断甲醇和异丙醇分别在升温和室温操作下具有优势。
The electrooxidation properties of methanol and 2-propanol, which are both promising candidates for direct alcohol fuel cells (DAFCs), have been studied under elevated temperature and pressurized conditions. Sputter-deposited Pt and Pt–Ru electrodes were well-characterized and utilized for the electrochemical measurement of the alcohol oxidation at 25–100°C. The Pt electrode prepared at 600°C had a flat surface, and the Pt–Ru formed an alloy. The electrochemical measurements were carried out in a gas-tight cell under elevated temperature, which accompanies the pressurized condition. This is a representative example of the DAFC rising temperature operation. As a result, at 25°C, the onset potential of the 2-propanol oxidation is about 400mV more negative than that of the methanol oxidation, and current density of the 2-propanol oxidation exceeds that of the methanol oxidation. Conversely, at 100°C, the methanol oxidation current density overcomes that of 2-propanol, and the onset potentials of the two are almost the same. The highest current density for the methanol oxidation is obtained at the Pt:Ru=50:50 electrode, whereas at the Pt:Ru=35:65 for the 2-propanol oxidation. A Tafel plot analysis was employed to investigate the reaction mechanism. For the methanol oxidation, the number of electrons transferred during the rate-determining process is estimated to be 1 at 25°C and 2 at 100°C. This suggests that the methanol reaction mechanism differs at 25 and 100°C. In contrast, the rate-determining process of the 2-propanol oxidation at 25 and 100°C was expected to be 1-electron transfer which accompanies the proton-elimination reaction to produce acetone. Consequently, it is deduced that methanol and 2-propanol have an advantage under the rising temperature and room temperature operation, respectively.