Solid oxide fuel cells (SOFC) are highly efficient devices for the conversion of the chemical energy stored in a range of fuels directly into electrical energy. Their inherent high efficiency results in less fossil fuel consumption and green house gas emissions compared to other energy conversion technologies. This Materials World Network project focuses on the development of a novel class of materials for use in the electrodes in SOFC that will increase both their efficiency and long-term durability, which will in turn help to hasten their commercialization. The specific materials that are being investigated, transition metal doped titanates and vanadates, undergo structural transformations upon exposure to reducing conditions that result in the precipitation of catalytically active metal nanoparticles on their surfaces. These metal nanoparticles catalyze the chemical reactions that take place in the fuel cell electrodes, thereby improving the device performance. The mechanism of this process is being determined and this insight will be used to design electrode compositions and microstructures with optimal properties. Researchers at the University of Pennsylvania in the US and the University of St. Andrews in the United Kingdom will collaborate on the project. This collaboration will include student exchanges at both graduate and undergraduate levels that will enhance the students' education and better prepare them to be the technological leaders of the future.
Solid oxide fuel cells (SOFC) have potential as highly efficient devices for the conversion of the chemical energy stored in a range of fuels directly into electrical energy. Electrocatalytic materials that are stable under SOFC operating conditions are needed, however, for this potential to be realized. In this Materials World Networ project, exsolution/dissolution of catalytically active transition metals out of and into an electronically conducting host oxide is being investigated as a means to tailor the catalytic properties of SOFC anodes and to regenerate activity that is lost due to sintering or adsorption of poisons. The specific materials systems under investigation include transition metal doped conducting titanates and vanadates which have the perovskite structure. The mechanism of the exsolution of transition metals, such as Ni, Pt, or Pd, from these host oxides under reducing conditions, its dependence on the oxide composition and defect chemistry, and the relationships between microstructure and electrochemical performance is being determined. The interaction of the exsolved metal nanoparticles with the oxide surface will also be characterized and the insight obtained in these studies will be used to design materials systems for which the exsolved metal nanoparticles are highly stable and resistant to coarsening via Ostwald ripening. The use of dissolution/exsolution cycles as an in situ means to regenerate catalytic activity in working SOFCs will also be investigated.
This project is supported by the Ceramics Program and Office of Special Programs, Division of Materials Research.
