In this study, the effects of forced convection on scanning electrochemical microscopy (SECM) experiments in feedback mode using ferrocenemethanol as redox mediator are presented. Forced convection, which enhances the mass transfer inside the system, was generated via an electrical high precision stirrer integrated into the SECM setup. A thin‐film interdigitated array electrode serving as model substrate was investigated with probe scan curves in z‐direction and SECM imaging in constant height mode utilizing ultramicroelectrodes (UME) with diameters (d_probe) of 25 μm and 12.5 μm. It was found that forced convection increased the overall current during SECM imaging without distorting distinctive features of the imaged structure when working with a 25 μm UME at substrate‐to‐tip distances of 14 μm and 11 μm. Furthermore, the electrochemical contrast was improved under hydrodynamic conditions for a substrate‐to‐tip distance of 11 μm and scan rates of 5 μm s⁻¹, 10 μm s⁻¹, 20 μm s⁻¹ and 40 μm s⁻¹. When further decreasing the gap between the UME and the substrate to 9 μm almost no effects of the forced convection were observed. Consequently, for a 25 μm UME, forced convection led to higher currents and improved performance during SECM experiments in feedback mode at substrate‐to‐tip distances of 14 μm and 11 μm, whereas no effects were observed for a 12.5 μm UME at a distance of 8 μm.

中文翻译：

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高精度搅拌产生的强制对流对反馈模式下扫描电化学显微镜实验的影响

在这项研究中，提出了在使用二茂铁甲醇作为氧化还原介体的反馈模式下强制对流对扫描电化学显微镜（SECM）实验的影响。强制对流是通过集成在SECM装置中的电动高精度搅拌器产生的，从而增强了系统内部的质量传递。利用z方向上的探针扫描曲线和恒定高度模式下的SECM成像，使用直径为d的超微_电极（UME），研究了用作模型基板的薄膜叉指阵列电极）分别为25μm和12.5μm。结果发现，当使用25μmUME以14μm和11μm的基底到尖端距离工作时，强制对流会增加SECM成像期间的总电流，而不会扭曲成像结构的明显特征。此外，该电化学对比度流体动力学条件下改进了的衬底到尖端的距离为11μm和5μm的s的扫描速率^-1，10微米小号^-1，20微米小号^-1和40微米小号^-1。当将UME和基板之间的间隙进一步减小至9μm时，几乎没有观察到强制对流的影响。因此，对于25μm的UME，在14微米和11微米的基体到尖端距离的反馈模式下，强制对流在SECM实验期间以反馈模式导致更高的电流并改善了性能，而12.5微米的UME在一定距离下未观察到影响8μm。