Electrotransport properties of SOFC cathode materials based on lanthanum cuprate doped with praseodymium and strontium oxides

Resumo

A complex study of thermal, conducting, and electrocatalytic properties of cuprates La_1.8‒xPr_xSr_0.2CuO_4–δ (х = 0.2; 0.4) with the K₂NiF₄ structure is carried out in order to assess their prospects as the cathode materials for solid-oxide fuel cells. The thermal analysis reveals stability of samples heated up to 950°С in air. The conductivity of cuprates measured in the temperature range of 100–900°С and the partial oxygen pressure from 10^–3 to 1 atm is of the metallic nature and varies from 70 to 40 S/cm in the temperature interval of 500–900°С in air. The studies of chemical stability of cuprates with respect to solid electrolytes demonstrate the absence of their chemical interaction with Ce_0.9Gd_0.1O_1.95 (GDC) at 900°С and with La_0.8Sr_0.2Ga_0.85Mg_0.15O_3–δ (LSGM) at 1000°C after 25 h annealing. For La_1.6Pr_0.2Sr_0.2CuO_4–δ electrodes deposited on the surface of GDC or LSGM solid electrolytes, the studies of electrocatalytic activity in the oxygen reduction reaction demonstrate that the smallest polarization resistance is typical of electrodes deposited on the GDC surface.