Further Insights into the Formic Acid Oxidation Mechanism on Platinum: pH and Anion Adsorption Effects
Further Insights into the Formic Acid Oxidation Mechanism on Platinum: pH and Anion Adsorption Effects
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DOI：
10.1016/j.electacta.2015.08.155
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发表时间：
2015-10-20
影响因子：
6.6
通讯作者：
Feliu, Juan M.
中科院分区：
文献类型：
--
作者：
Perales-Rondon, Juan V.;Brimaud, Sylvain;Feliu, Juan M.
采用循环伏安法研究了在不同浓度的硫酸根、高氯酸根、磷酸根和氯离子存在下，多取向铂电极上甲酸氧化反应中电解液pH值的影响。纯硫酸盐和高氯酸盐溶液中负扫描方向上的峰电流与pH值的曲线非常相似。对于这些溶液，最大氧化电流随着pH值的增加而稳定增加，直到pH值接近5，然后是一个平台期，直到pH值10。这表明反应通过类似的反应机理进行，其中溶液中HCOO-阴离子的浓度起着关键作用。相反，对于含磷酸盐或氯化物的溶液，最大氧化电流显示钟形pH-氧化电流相关性，其确切形状取决于阴离子浓度。我们建议，在这些情况下的pH值-电流的关系是修改竞争的特定吸附的阴离子作为网站阻塞旁观者物种。这些结果将讨论与兼容的机制的建议。(C)2015爱思唯尔有限公司版权所有。
The influence of the electrolyte pH in the formic acid oxidation reaction on a polyoriented Pt electrode in the presence of different anions, including sulfate, perchlorate, phosphate and chloride, in different concentrations has been investigated, using cyclic voltammetric measurements. The curves of the peak currents in the negative scan direction vs. the pH in pure sulfate and perchlorate solutions are very similar. For these solutions, the maximum oxidation currents increase steadily with increasing pH up to pH approximate to 5, followed by a plateau until pH 10. This suggests that the reaction proceeds via a similar reaction mechanism, in which the concentration of HCOO- anions in solution plays a key role. For phosphate or chloride containing solutions, in contrast, the maximum oxidation currents show a bell-shaped pH-oxidation current correlation, whose exact shape depends on the anion concentration. We suggest that in these cases the pH-current relation is modified by competing specific adsorption of anions which act as site blocking spectator species. These results will be discussed in relation with compatible mechanistic proposals. (C) 2015 Elsevier Ltd. All rights reserved.