Catalytic activities of PtBi nanoparticles toward methanol electrooxidation in acid and alkaline media
Catalytic activities of PtBi nanoparticles toward methanol electrooxidation in acid and alkaline media
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DOI：
10.1016/j.jpowsour.2012.11.150
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发表时间：
2013-05
影响因子：
9.2
通讯作者：
Minli Yang
中科院分区：
文献类型：
--
作者：
Minli Yang
根据预设的组成从水溶液中电沉积出球形 PtBi 纳米颗粒。它们对甲醇电氧化的催化活性通过循环伏安法和计时电流法在酸性介质中和首先在碱性介质中进行了检查。实验结果表明，在酸性或碱性介质中，甲醇电氧化在 PtBi 上的起始电位低于 Pt。催化活性的提高归因于 PtBi 中铋的电子效应。在较高的过电位下，电解质的酸性对PtBi和Pt的甲醇电氧化动力学产生不同的影响。在酸性介质中，PtBi 在 0.460 V 以上的甲醇氧化能力上不如 Pt，因为 PtBi 上连续的 Pt 位点较少，不足以对甲醇分子进行吸附和脱氢。在碱性介质中，当电压高于 0.768 V 时，PtBi 上的氧化电流变得比 Pt 上的氧化电流高得多。电流的增加可归因于双功能机制。 PtBi 表面的 Bi2O5 位点用于 OHad 吸附，Pt 位点用于甲醇脱氢。 PtBi 纳米粒子在碱性介质中更好的催化活性表明它们在碱性直接醇燃料电池中的应用前景。
Spherical PtBi nanoparticles are electrodeposited from aqueous solution according to the preset composition. Their catalytic activities toward methanol electrooxidation are examined by cyclic voltammetry and chronoamperometry in acid media and first in alkaline media. Experimental results show that, methanol electrooxidation has lower onset potentials on PtBi than on Pt in either acid or alkaline media. The improved catalytic activities are due to the electronic effects of bismuth in PtBi. At higher overpotentials, the electrolyte acidity has produced different influences on the kinetics of methanol electrooxidation on PtBi and Pt. In acid media, PtBi is inferior to Pt for methanol oxidation at above 0.460 V, because that fewer continuous Pt sites on PtBi are not enough for the adsorption and dehydrogenation of methanol molecules. In alkaline media, the oxidation current on PtBi becomes much higher than that on Pt at above 0.768 V. The raised current can be credited to the bifunctional mechanism. Bi2O5sites on PtBi surface serve for OHadadsorption and Pt sites for methanol dehydrogenation. The better catalytic activity of PtBi nanoparticles in alkaline media suggests their promising application in alkaline direct alcohol fuel cells.