Nanocomposite fuel cells

Official URL: http://risc01.sabanciuniv.edu/record=b2057962 (Table of Contents)

The interactions between the components of the nanocomposite fuel cell electrolyte were investigated. Surface charges were thought to be responsible for the differences in the ionic conductivity. The literature claims that ionic transport in hybrid electrolytes does not happen primarily in the solid oxide or the matrix phase but at the interface between them. The surface charges of oxide particles are dissociating the matrix salt molecules into positive and negative ion complexes. The complex with the opposite charge sticks to the surface of the particles. The counter-ion moves freely under the influence of the electrical field, thus causing fast ionic current. Therefore, it is postulated that by modifying the surface charges one can affect the ionic conductivity. The strength of surface acidity was manipulated by reduction without significantly changing the chemistry of the oxide material. TiO2 (Rutile) was selected as the material whose surface charge was altered by reduction. Ionic conductivities were measured by impedance spectrometry. Surface charges were obtained by isoelectric point measurements. The amounts of reduction were measured by thermogravimetric analysis. Oxides with different surface charges resulted in different ionic conductivities. Substoichiometric oxides had different strength of surface charges that resulted in correlated ionic conductivities. These interactions of surface charges and the ionic conductivities are explained with the help of a developed model for the composite electrolyte.