Figueiredo Marta C, Hiltrop Dennis, Sundararaman Ravishankar, Schwarz Kathleen A, Koper Marc T M
Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Laboratory of Industrial Chemistry, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
Electrochim Acta. 2018;281. doi: 10.1016/j.electacta.2018.05.152.
In this work we investigate the effects of the diffuse double layer thickness on the electrochemical Stark tuning and oxidation of carbon monoxide at Pt(111) surfaces in perchloric acid solution. The diffuse double layer thickness was modified by changing the concentration (ionic strength) of the supporting electrolyte. The Stark tuning slope of the adsorbed CO was evaluated with Fourier Transformed Infrared Spectroscopy, and the CO oxidation was monitored with cyclic voltammetry. The results show that both electrochemical Stark tuning and oxidation are independent of the HClO concentration of the supporting electrolyte, revealing the absence of diffuse layer effects on the aqueous Pt(111)/CO system. By comparison to previously reported theoretical calculations, we attribute this insensitivity to the special double layer structure of Pt(111)/CO, in which the potential drop occurs primarily between the terminating oxygen of the adsorbed CO adlayer and first water layer of the electrolyte, making the properties of adsorbed CO nearly independent of the ionic strength of the electrolyte.
在本工作中，我们研究了弥散双层厚度对高氯酸溶液中Pt(111)表面一氧化碳的电化学斯塔克调谐和氧化的影响。通过改变支持电解质的浓度（离子强度）来改变弥散双层厚度。用傅里叶变换红外光谱法评估吸附CO的斯塔克调谐斜率，并用循环伏安法监测CO的氧化。结果表明，电化学斯塔克调谐和氧化均与支持电解质的HClO浓度无关，这表明在水相Pt(111)/CO体系中不存在弥散层效应。通过与先前报道的理论计算结果相比较，我们将这种不敏感性归因于Pt(111)/CO的特殊双层结构，其中电位降主要发生在吸附的CO吸附层的末端氧与电解质的第一水层之间，使得吸附CO的性质几乎与电解质的离子强度无关。
