Electrogenerated silica thin films exhibiting a regular hexagonal packing of vertically‐aligned mesopore channels are promising for preconcentration electroanalysis. This work demonstrates the critical role of film thickness on their sensing performance using paraquat as a model analyte, based on mesoporous silica films prepared by electrochemically assisted self‐assembly performed for various deposition times. Films prepared with too short synthesis times (<10 s) led to deposits covering partially the electrode surface and suffered from rather poor sensing performance. Then, uniformly deposited films were obtained (between 10 and 15 s), and sensitivity rose up by increasing deposition times, whereas some limitations started to occur with much thicker films (>15 s deposition times) as a result of less electrochemically accessible paraquat accumulated far away from the electrode surface and restricted mass transport through the whole film thickness. These limitations were also confirmed on the basis of multi‐layered mesoporous silica films, suggesting a behavior that might be typical for other types of film‐modified electrodes.

中文翻译：

---

膜厚对定向介孔二氧化硅修饰电极预富集电分析的关键影响

具有垂直排列的中孔通道的规则六边形堆积的电沉积二氧化硅薄膜有望用于预浓缩电分析。这项工作证明了百草枯作为模型分析物时，膜厚对其传感性能的关键作用，这是基于在各种沉积时间下通过电化学辅助自组装制备的介孔二氧化硅膜。用太短的合成时间（<10 s）制备的薄膜会导致沉积物部分覆盖电极表面，并具有相当差的传感性能。然后，获得了均匀沉积的薄膜（在10到15 s之间），并且灵敏度随着沉积时间的增加而上升，而厚得多的薄膜开始出现一些局限性（> 15 s的沉积时间）是由于远离电极表面积累了较少的电化学可接触的百草枯，并限制了整个膜厚度的质量传递。在多层介孔二氧化硅薄膜的基础上也证实了这些局限性，表明了其他类型的薄膜修饰电极可能具有的典型行为。