Abstract
? 2022 Elsevier B.V.Novel perovskite-type A-site calcium-doped Nd1–xCaxBaCo2O5+δ oxides were studied in terms of oxygen electrode materials for reversible solid oxide cells (RSOCs). The electrode of x ≤ 0.2 was composed of a tetragonal perovskite structure with a P4/mmm space group. A Ca2+ dopant was used to improve the thermal expansion coefficient (TEC), conductivity, and electrochemical properties of the NdBaCo2O5+δ oxides, with TEC and conductivity values of Nd1–xCaxBaCo2O5+δ (x = 0–0.2) of 17.5–16.2 × 10?6 K?1 and 960.4–1068 S cm?1, respectively. The X-ray photoelectron spectroscopy results indicated that Ca2+ doping has a beneficial influence on the surface oxygen adsorption properties and the increase in the concentration of Co4+. On the basis of the first-principles density functional theory, doping with Ca2+ leads to easier oxygen release and uptake. The area specific resistance of the x = 0.2 electrode was 0.058 Ω cm2 at 700 °C, whereas at 800 °C, the cell using the x = 0.2 oxygen electrode exhibited a maximum power density of 740 mW cm?2 when H2 was used as the fuel, and the current density of the electrolytic pure CO2 at 1.5 V was 1.68 A cm?2. These attractive electrochemical properties suggest that Ca-based doping is an effective method for developing (reversible solid oxide cell) RSOC oxygen electrodes.
NSTL
Elsevier