The Microelectrode Insulator Influences Water Nanodroplet Collisions
The Microelectrode Insulator Influences Water Nanodroplet Collisions
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DOI：
10.1021/acs.analchem.3c00287
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发表时间：
2023-04-24
影响因子：
7.4
通讯作者：
Dick，Jeffrey E.
中科院分区：
文献类型：
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作者：
Vannoy，Kathryn J.;Renault，Christophe;Dick，Jeffrey E.
研究极小体积(从阿特升到皮升)的化学反应对于理解化学在所有相关尺度上是如何进行的很重要。随机电化学是研究单个纳米液滴动力学的有力工具，一次一个。也许概念上最简单的实验是电流阻断实验，在该实验中，通过电化学方法观察到绝缘粒子的碰撞是通过电流的逐步减小来进行的。在这里，我们证明了纳米液滴在微电极上的碰撞并不像水滴吸附到电极上以阻止电流那么简单，微电极(玻璃绝缘体)周围的环境在电化学碰撞响应中起着关键作用。我们使用相关的光电化学测量来了解在石油中十甲基二茂铁的非均相氧化过程中，当纳米水滴与微电极碰撞时的各种电化学响应。安培电流不仅报告了电流阻塞，而且还报告了纳米液滴的合并事件和对微电极周围玻璃的优先润湿。用二氯二甲基硅烷处理玻璃在工作电极周围创造了一个疏水环境，并观察到了因吸收照射的纳米颗粒而预期的简单电流阻断响应。这些结果突出了工作电极周围环境对纳米液滴碰撞研究的重要性。
Studying chemical reactions in very small (attoliter to picoliter) volumes is important in understanding how chemistry proceeds at all relevant scales. Stochastic electrochemistry is a powerful tool to study the dynamics of single nanodroplets, one at a time. Perhaps the most conceptually simple experiment is that of the current blockade, where the collision of an insulating particle is observed electrochemically as a stepwise decrease in current. Here, we demonstrate that nanodroplet collisions on microelectrodes are not as simple as water droplets adsorbing to the electrode to block current and that the environment immediately around the microelectrode (glass insulator) plays a pivotal role in the electrochemical collision response. We use correlated opto-electrochemical measurements to understand a variety of electrochemical responses when water nanodroplets collide with a microelectrode during the heterogeneous oxidation of decamethylferrocene in oil. The amperometric current reports not only on current blockades but also on nanodroplet coalescence events and preferential wetting to the glass around the microelectrode. Treating the glass with dichlorodimethylsilane creates a hydrophobic environment around the working electrode, and the simple current blockade response expected from the absorption of insolating nanoparticles is observed. These results highlight the importance of the environment around the working electrode for nanodroplet collision studies.