Microfluidic and Surface Electrochemistry

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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.