Oxygen electrode reaction on Nd2NiO4+δ cathode materials: impedance spectroscopy study

The oxygen reduction at the surface of Nd2NiO4+δ mixed conducting cathodes has been studied in the temperature range 400–1100 K using two kinds of cells: (i) porous cathodes deposited on a standard electrolyte pellet of yttria-stabilized zirconia (YSZ) and (ii) YSZ films sputtered on dense pellets of Nd2NiO4+δ. The studies on dense cathodes allowed to determine their electrical conductivity characteristics independently of their microstructure. The performances of these cathode materials were measured using the complex impedance spectroscopy at various temperatures and oxygen partial pressures. Compared to manganite perovskites, porous electrodes of these oxides exhibit promising electrocatalytic properties (i.e. lower polarization resistances) in agreement with the values of the surface exchange coefficient, k, and of the oxygen tracer diffusion coefficient, D*, previously measured by SIMS. Their behavior, especially the dependence of the polarization resistance on temperature and oxygen partial pressure was tentatively modelled.