Surface and Microfluidic Electrochemistry

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The proposed electrochemical research is directed to the understanding of the details of electrocatalytic reactions of small organic molecules at noble metal electrodes. Oxidation of small (liquid) organic molecules to CO2 is the basis for direct liquid fuel cells (DLFCs). Reduction of CO2 to small organic molecules can replace fossil fuel routes to these molecules, and the combination of DLFCs with CO2 reduction is one way forward to a sustainable carbon neutral chemical economy.**** These reactions are complex multistep reactions, which generally involve many surface species and solution intermediates, and perfect selectivity to the desired product is not readily achieved. To optimize selectivity requires detailed study of the nature of these species and the kinetics of the transformations. The approach is to understand a few model electrocatalytic processes and find information that is predictive for related catalysts or reactions, rather than to find new catalysts through empirical searches.**** A combination of electrochemical, microfluidic and spectroscopic methods will be used to elucidate the individual steps in these reactions. In particular new combinations of these methods that look at these transformations in real time will be pursued. Recently, examples have been found where the selectivity can be dramatically changed by the local conditions, such as the local pH near the surface or the surface morphology. To understand these phenomena, the detailed way in which the mass transport in solution is coupled to the surface reactions must be understood.**** An important tool to understand mass transport effects is in microfluidic electrochemical devices, in which flow past a reacting electrode sweeps intermediates and products downstream to a detector. New electrochemical detection methods will be developed. We will also add downstream spectroscopic methods, including Raman (collaboration with Brolo, UVic) and DEMS (collaboration with Seland and Sunde, NTNU, Norway).**** We will use fast electrochemical methods to understand the kinetics, including those based on dynamic electrochemical impedance spectroscopy, which can capture impedance spectra as a function of time. We will extend the capabilities of this method and of supporting theory.**** The thin oxide films on Pt and Pd electrodes typically inhibit electrocatalytic activity. Despite study for many years, the nature of the oxide, how it grows and how it influences electrocatalysis is poorly understood. In collaboration with Drnec (European Synchrotron Radiation Facility) and Magnussen (Kiel), we will apply synchrotron surface X-ray diffraction to study the structure of the oxide and the kinetics of its formation.**** The combined use of multiple electrochemical and spectroscopic methods will give a comprehensive picture about the electrocatalytic reaction mechanisms of selected organic oxidation and CO2 reduction reactions.******