Characterization of impregnated GDC nano structures and their functionality in LSM based cathodes

Porous composite cathodes of LSM–YSZ (lanthanum strontium manganite and yttria stabilized zirconia) were impregnated with GDC (gadolinia doped ceria) nano particles. The impregnation process was varied using none or different surfactants (Triton X-45, Triton X-100, P123), and the quantity of impregnated GDC was varied via the precursor concentration and number of impregnation cycles. The obtained structures were characterized with Kr and N2 adsorption/desorption isotherms, mercury intrusion porosimetry, in-situ high temperature X-ray diffraction, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The performance of the impregnated LSM–YSZ cathode was correlated with the GDC load, and the density and connectivity of the GDC phase, whereas crystallite size and surface area appeared less significant. The impregnated GDC was indicated to be preferentially situated on the LSM phase and the LSM grain boundaries. The observations suggest that the improved performance associated with GDC nano particles is related to the particles placed near the TPB (triple phase boundary) zone. The GDC extends the TPB by creating an ionic conducting network on top of the LSM particles and on top of the insulating low conducting zirconates at the LSM–YSZ interface.