Microfluidic and Surface Electrochemistry

本研究旨在了解燃料如甲酸、甲醇、乙醇或甘油的氧化反应。这些都是可以从生物来源生产的燃料，因此在燃料电池中使用它们可以导致碳中性的可持续能源系统。了解分子水平上发生的事情能够改进电化学装置，例如燃料电池，其操作通过在电极表面上发生的反应进行。这些反应比氢燃料电池中使用的更成熟的氢氧化更复杂，因为涉及几种表面物质，并且存在产生不期望的可溶性产物的副反应。我们将开发新的方法来识别这些物种，确定它们有多少，以及它们如何相互转化。 我们将使用微流控电化学技术来表征复杂的化学。在最简单的变化中，分子沿着一个非常薄的通道流动，在那里它们通过不同电压的电极。第一个电极进行反应，下游的电极作为检测器，捕获和计数第一个电极产生的分子。由于通道非常薄，捕获非常有效，检测过程非常灵敏。此外，我们将使用电化学石英晶体微天平（EQCM），它可以灵敏和快速地测量表面上分子的质量（因此它们的数量）。EQCM与微流体的结合将使这些反应的细节得以解释。分析将通过使用阻抗方法来增强，阻抗方法具有两个优点：它们可以同时测量在不同时间尺度上发生的过程，并且可以在不显著改变被测系统的情况下进行测量。

This research is directed at an understanding of reactions of oxidation of fuels such as formic acid, methanol, ethanol or glycerol. These are all fuels that can be produced from biological sources, and so using them in fuel cells can lead to a sustainable energy system that is carbon neutral. A knowledge of what is happening at the molecular level enables improvement of electrochemical devices such as fuel cells whose operation occurs via reactions occurring on an electrode surface. These reactions are more complicated than for the more established hydrogen oxidation used in hydrogen fuel cells, because there are several surface species involved and there are side-reactions that give undesired soluble products. We will develop new methods to identify these species, determine how much of them there are, and exactly how they interconvert. We will use microfluidic electrochemistry techniques to characterize the complex chemistry. In the simplest variation, the molecules are flowed down a very thin channel where they pass electrodes at different voltages. The first electrode carries out the reaction, and the downstream ones act as detectors, capturing and counting the molecules produced at the first electrode. Because the channel is very thin, the capture is very efficient and the detection process is very sensitive. In addition we will use the electrochemical quartz-crystal microbalance (EQCM), which can sensitively and rapidly measure the masses of the molecules on the surface (and therefore their amounts). The combination of EQCM with microfluidics will enable the details of these reaction to be interpreted. The analysis will be enhanced by using impedance methods, which have two advantages: they can simultaneously measure processes happening on different time scales, and can measure without significantly changing the systems being measured.