Deng Qibo, Gosslar Daniel-Hendrik, Smetanin Maxim, Weissmüller Jörg
Institut für Werkstoffphysik und Werkstofftechnologie, Technische Universität Hamburg-Harburg, Hamburg, Germany.
Phys Chem Chem Phys. 2015 May 7;17(17):11725-31. doi: 10.1039/c5cp00167f.
We investigate the impact of the surface roughness on the experimental value of the electrocapillary coupling coefficient, ς. This quantity relates the response of electrode potential, E, to tangential elastic strain, e, and also measures the variation of the surface stress, f, with the superficial charge density, q. We combine experiments measuring the apparent coupling coefficient ςeff for gold thin film electrodes in weakly adsorbing electrolyte with data for the surface roughness determined by atomic force microscopy and by the capacitance ratio method. We find that even moderate roughness has a strong impact on the value of ςeff. Analyzing the mechanics of corrugated surfaces affords a correction scheme yielding values of ς that are invariant with roughness and that agree with expectations for the true coupling coefficient on ideal, planar surfaces. The correction is simple and readily applied to experiments measuring ςeff from surface stress changes in cantilever bending studies or from the potential variation in dynamic electro-chemo-mechanical analysis.
我们研究了表面粗糙度对电毛细管耦合系数ς实验值的影响。该系数将电极电位E的响应与切向弹性应变e联系起来，同时也测量表面应力f随表面电荷密度q的变化。我们将测量弱吸附电解质中金薄膜电极表观耦合系数ςeff的实验与通过原子力显微镜和电容比法确定的表面粗糙度数据相结合。我们发现，即使是适度的粗糙度也会对ςeff的值产生强烈影响。分析波纹表面的力学原理提供了一种校正方案，可得出与粗糙度无关且与理想平面上真实耦合系数预期相符的ς值。该校正方法简单，可轻松应用于通过悬臂梁弯曲研究中的表面应力变化或动态电化学机械分析中的电位变化来测量ςeff的实验。
