Layered structures of yttria-stabilized zirconia sandwiched between platinum/ yttria-stabilized zirconia composites: Layered structures of yttria-stabilized zirconia sandwiched between platinum/ yttria-stabilized zirconia composites

Layered structures of cubic yttria-stabilized zirconia (YSZ) sandwiched between two layers of platinum/YSZ composites with the platinum concentration varying between 20 and 55 vol % were prepared. Large double-layer capacitances were obtained due to the presence of large three-dimensional electrode surface areas in the composite layers. The layers were subjected to image analysis obtained from scanning electron microscopy micrographs. The specific surface area of the platinum particles decreased from ∼17×103 to ∼13.5×103 cm2/cm3 with increasing Pt concentration. Image analyses obtained with an in-lens detector revealed that the effective surface area of the Pt particles that were part of a conducting percolative network increased with Pt concentration to ca. 11×103 cm2/cm3 at a Pt metal volume fraction of 0.50. Impedance spectroscopy measurements performed at 550 °C demonstrated that the capacitance increased with increasing Pt concentration in the composite layer and optimal values as high as 4.3±1.3 kF/m2 at 50 vol % Pt were recorded. The specific electrode surface area calculated from this data was in good agreement with the data obtained from image analysis.