Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite SrCoMoO as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells.

Lanthanum (La)-doped double perovskites SrCoMoO (SrLaCoMoO, 0.00 ≤ ≤ 0.03) were synthesized via the citrate-nitrate autocombustion route. The Reitveld refinement analysis of X-ray diffraction reveals the tetragonal symmetry as the main phase with space group 4/ and also confirms the presence of some peaks corresponding to extra phase SrMoO. The SEM micrograph images reflect that grains are in irregular shape and sizes for all samples. Average grain size gradually decreases with the increase of the SrMoO phase. The X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of mixed valence states of Mo/Mo, Co/Co, and O-lattice/O-chemisorbed/O-physisorbed species. Coefficient of thermal expansion (CTE) analysis shows that the particular composition SrLaCoMoO has the lowest CTE value among the compositions studied. The electrical conductivity of SrCoMoO is enhanced effectively by doping La at Sr sites. The measured area-specific resistance (ASR) for the composition SrLaCoMoO (SLCM03) is found to be appreciably low, ∼0.053 Ohm cm at 800 °C. The obtained highest electrical conductivity with the lowest activation energy and low ASR value for the composition SrLaCoMoO encompasses it as a promising candidate for anode material in the intermediate-temperature solid oxide fuel cell (IT-SOFC) application.