Deng Qibo, Weissmüller Jörg
Institut für Werkstoffphysik und Werkstofftechnologie, Technische Universität Hamburg-Harburg , Hamburg, 21073 Germany.
Langmuir. 2014 Sep 2;30(34):10522-30. doi: 10.1021/la501353g. Epub 2014 Aug 21.
The electrocapillary coupling coefficient, ς, measures the response of the electrode potential, E, to tangential elastic strain at the surface of an electrode. Using dynamic electro-chemo-mechanical analysis, we study ς(E) simultaneously with cyclic voltammetry. The study covers extended potential intervals on Au, Pt, and Pd, including the electrosorption of oxygen species and of hydrogen. The magnitude and sign of ς vary during the scans, and quite generally the graphs of ς(E) emphasize details which are less obvious or missing in the cyclic voltammograms (CVs). Capacitive processes on the clean electrode surfaces exhibit ς < 0, whereas capacitive processes on oxygen-covered surfaces are characterized by ς < 0 on Au but ς > 0 on Pt and Pd. The findings of ς < 0 during the initial stages of oxygen species adsorption and ς > 0 for hydrogen electrosorption agree with the trend that tensile strain makes surfaces more binding for adsorbates. However, the large hysteresis of oxygen electrosorption on all electrodes raises the question: is the exchange current associated with that process sufficient for its measurement by potential response during small cyclic strain?
电毛细管耦合系数ς用于衡量电极电位E对电极表面切向弹性应变的响应。我们采用动态电化学机械分析方法，结合循环伏安法同时研究ς(E)。该研究涵盖了金、铂和钯上的扩展电位区间，包括氧物种和氢的电吸附过程。在扫描过程中，ς的大小和符号会发生变化，一般来说，ς(E)的曲线突出了循环伏安图（CVs）中不太明显或缺失的细节。清洁电极表面的电容过程表现为ς < 0，而氧覆盖表面的电容过程在金上的特征是ς < 0，在铂和钯上则为ς > 0。氧物种吸附初始阶段ς < 0以及氢电吸附时ς > 0的发现，与拉伸应变使表面对吸附质的结合力更强这一趋势相符。然而，所有电极上氧电吸附的较大滞后现象引发了一个问题：与该过程相关的交换电流是否足以通过小循环应变期间的电位响应来测量？
