Electron and ion transport in metal oxides is a critical component of many energy conversion processes, including fuel cells, batteries, and photoelectrochemical cells. First principles quantum mechanics can be used not only to evaluate transport properties in prospective materials but also to reveal the origins of trends in transport, which in turn allow design principles to be extracted to improve materials further. We have a major research effort to use quantum mechanics techniques to search for robust, efficient, and inexpensive materials for photo-catalytic electrodes (PCEs) that could convert sunlight, carbon dioxide, and water into fuels and for solid oxide fuel cells (SOFCs) that convert fuels to electricity.  PCEs providing fuels to SOFCs could represent a pathway to solar energy storage as fuels and clean, efficient, renewable electricity. This talk will present results of our SOFC research, in which we are focused on cathode optimization, often considered the limiting factor in reducing the high operating temperatures of current SOFCs. Porous electrodes can be readily synthesized for SOFCs such that gas transport is facile. If oxide ion diffusion and electron transport can be enhanced, along with rapid dissociative adsorption of dioxygen on the cathode surface, lower temperatures could be used, which would facilitate wider deployment. Key properties of conventional and novel materials, along with some new design principles, will be discussed.  The work is revealing which mixed oxides are likely to provide efficient SOFC cathodes. Time permitting we will also present quantum mechanics methods for properly treating charge transfer at electrode surfaces, such as in the crucial oxygen reduction reaction at fuel cell cathodes.

First principles quantum mechanical evaluation of mixed electron-ion conductors and the oxygen reduction reaction

247th National Meeting (2014)

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