Hierarchical nanoporous La_1.7Ca_0.3CuO_4-δ and La_1.7Ca_0.3Ni_xCu_1-xO_4-δ (0.25 ≤ x ≤ 0.75) as potential cathode materials for IT-SOFCs

Hierarchically nanoporous materials based on layered perovskite oxides La_1.7Ca_0.3Ni_xCu_1−xO_4−δ (x = 0, 0.25, 0.50 or 0.75) have been synthesized by a facile citrate-modified evaporation-induced self-assembly (EISA) method. These La_1.7Ca_0.3Ni_xCu_1−xO_4−δ oxides have been evaluated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with Ni–YSZ cermet supported type cells. It was found that La_1.7Ca_0.3CuO_4−δ cathode exhibits the maximum power density at high temperature (e.g., 1.5 W cm⁻² at 850 °C), while La_1.7Ca_0.3Ni_0.75Cu_0.25O_4−δ cathode shows the highest power density at intermediate temperature (e.g. 0.71 W cm⁻² at 750 °C) using humidified H₂ and air as the fuel and oxidant, respectively. The electrochemical performance of single cells with La_1.7Ca_0.3Ni_0.75Cu_0.25O_4−δ cathode materials with different morphologies demonstrated better performance in the intermediate temperature range when using the cathode prepared by the citrate-modified EISA method, which has a bigger grain size, but with higher surface area and pore volumes.