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Sustainable energy has emerged as the most pressing challenge facing humanity in the 21st century. Fuel cells, because of their high efficiencies and benign emissions, will likely play an important role in a sustainable energy future. In this work we hope to leverage new materials discovery against tailored architectures in order to obtain unprecented fuel cell power outputs. Funding for this work is provided by the National Science Foundation (DMR-0840365 and DMR-0906543).

Solid acids are a fascinating class of materials built upon hydrogen bonded oxyanion groups. In contrast to polymeric proton conductors, these compounds conduct protons without the assistance of mobile water molecules, opening new technological possibilities and scientific avenues. Our success in fabricating and demonstrating fuel cells based on these electrolytes has led to the spin-off company, Superprotonic, Inc. The work is supported by the National Science Foundation (DMR-0906543).

    • Here's a "popular press" article on our solid acid fuel cells which appeared in the Caltech publication ENGenious.

    • And here's a video put together by Science and Technology News Network.
  • Proton Conducting Perovskites

    Several oxides of the perovskite structure, notably BaCeO3, BaZrO3, SrCeO3 etc., can, after appropriate doping so as to contain oxygen vacancies, adsorb significant quantities of water into their bulk structures.  The protons associated with the incorporated water are present in the form of hydroxyl groups and can easily migrate from one oxygen ion to the next.  This easy migration results in a high conductivity and materials that are useful for a range of devices, from fuel cells to hydrolysis cells to hydrogen separation membranes. This work is supported by the Gordon Moore Foundation, through the Caltech Center for Sustainable Energy Research.

  • Solid Oxide Fuel Cells

    Solid oxide fuel cells (SOFCs) operate at high temperatures, and, as a consequence, they can utilize hydrocarbon fuels, they provide for efficient catalysis, and they exhaust 'high quality' waste heat that can be used for additional power generation. High temperature operation, however, has generally been responsible for the high cost of SOFCs and for their undesirability for portable applications. Our efforts in solid oxide fuel cells span a number of activities. These include the use of ceria as an electrolyte for reduced temperature operation, the incorporation of ceria in fuel cell anodes for enhanced electrooxidation activity for complex hydrocarbon fuels, the development of alternative perovskite cathodes for high activity oxygen electroreduction, and the operation of fuel cells in so-called single chamber mode for portable power. This work is funded, in part, by the Global Climate and Energy Program of Stanford University, supported by a consortium of industrial partners, and formerly supported by the Office of Naval Research, through the MURI program. Additional supported is provided by the National Science Foundation (DMR-0840365).

  • Solar-Driven Thermochemical Fuel Production

Variable valence oxides have the important characteristic that at high temperatures, they release oxygen, due to thermodynamic driving force, whereas thermodynamics drives oxygen reabsorbtion at lower temperatures. At the lower temperature, if gases such as water or carbon dioxide are used to reoxidize the material, the reaction generates a reduced fuel such as hydrogen or carbon dioxide as the reaction product. Such thermochemical production, when driven by solar thermal heating, can be used for solar fuel generation. In this work we develop new materials with desirable thermodynamic and kinetic properties for thermochemical solar fuel synthesis. Our initial studies have focused on doped ceria and the results suggest that solar to fuel conversion efficiencies of ~20% can be achieved even in the absence of heat recovery and that fuels ranging from hydrogn and carbon dioxide to syngas and methane can be produced with extremely rapid kinetics. This work is supported by the National Science Foundation (CBET-0829114) and by eSolar.

People and Agencies

No post-doctoral positions are currently open.

  • Undergraduate Opportunities

SURF projects for 2014:

Junior or sophomore Caltech students with prior research experience preferred, and, in some cases, only Caltech students will be considered. See individual project descriptions (some still in preparation) for course requirements, recommended prior experience and additional resources.

In addition to applying through the SURF program, interested candidates should send a resume, transcript and at least one letter of recommendation to Prof. Sossina Haile and the direct laboratory mentor specified in the project title before requesting further information. Please do not rely on the SURF office to forward this information.



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Last modified: February 14, 2014