Characterization of PrNiO3-δ as oxygen electrode for SOFCs

The praseodymium nickelate PrNiO3-delta was recently identified as one of the decomposition products of Pr2NiO4+delta oxygen electrode, raising the question of the role of this perovskite compound on the Pr2NiO4+delta performance and ageing behaviour. Herein, the electrochemical properties of PrNiO3-delta as cathode for Solid Oxide Fuel Cells (SOFCs) is reported. PrNiO3-delta, synthesized from the citrate-nitrate route, cristallizes in an orthorhombic structure (S.G.: Pnma). Under air, a transition to high temperature rhombohedral structure (S.G.: R-3c) occurs at around 600 degrees C, while its oxygen vacancy amount increases from delta approximate to 0.05 at room temperature up to 0.10 at high temperature. Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterizations show that above 1000 degrees C, in air, PrNiO3-delta starts to decompose into Pr2NiO4+delta and NiO through an intermediate transformation into Pr 4 Ni3O10+delta. The value of the polarization resistance (R-p) of co-sintered GDC-PrNiO3-delta electrode, at 950 degrees C in air for 2 h, is 0.91 Omega cm(2) at 600 degrees C under air. It remains much higher than that of co-sintered GDC-Pr(2)Nio(4+delta) electrode (R-p = 0.15 Omega cm(2)), which means that the perovskite does not play any significant role in the electrochemical performance during long term operation of the Pr2NiO4+delta electrode. (C) 2018 Elsevier Masson SAS. All rights reserved.