Nanopore Patterned Pt Array Electrodes for Triple Phase Boundary Study in Low Temperature SOFC

Abstract

This paper describes the fabrication and investigation of morphologically stable model electrode structures with well-defined and sharp platinum/yttria-stabilized zirconia (YSZ) interfaces to study geometric effects at triple phase boundaries (TPBs). A nanosphere patterning technique using monodispersed silica nanoparticles, which are applied to the YSZ surface by the Langmuir–Blodgett method, is employed to deposit nonporous platinum electrodes containing close-packed arrays of circular openings 300–400 nm in diameter through which the underlying YSZ surface is exposed to the gas phase. These nanostructured dense Pt array cathodes exhibited better structural integrity and thermal stability at the solid oxide fuel cell (SOFC) operating temperature of when compared to porous sputtered Pt electrodes. More importantly, electrochemical studies on geometrically well-defined Pt/YSZ sharp interfaces demonstrated that the cathode impedance and cell performance both scale almost linearly with the aerial density of TPB length. These controlled experiments also demonstrated that when normalized with respect to TPB length, the performance of different cells with different TBP densities agree well each other, indicating that TPB length governs cell performance especially in the activation polarization regime, as expected. Cells with a higher TPB density achieved better fuel cell performance in terms of higher power density and lower electrode impedance.