Sr- and Mo-deficiency Sr1.95TiMo1-xO6-δ double perovskites as anodes for solid-oxide fuel cells using H2S-containing syngas

Sr- and Mo-deficiency Sr1.95TiMo1-xO6-delta (STM1-xO; x = 0-0.075) double perovskites are prepared and applied as potential anodes for solid-oxide fuel cells (SOFCs) operated in sulfur-containing syngas. The effect of Sr- and Mo- deficiency on the crystalline nature, electrical and thermal properties and electrochemical performance are investigated. The STM0.925O crystallizes in a single-phase cubic perovskite structure and has excellent thermal and chemical compatibilities with Ce0.9Gd0.1O1.95, Ce0.8Sm0.2O1.9 and La0.9Sr0.1Ga0.8Mg0.2O3-delta electrolytes. The conductivities of STM0.925O in H-2 at 550 degrees C-850 degrees C are higher than 160 S cm(-1). The polarization resistance (R-p) of STM0.925O is recorded as 1.451 Omega cm(2) at 850 degrees C in H-2, which is 51% lower than that in pristine Sr2TiMoO6, and the maximum power density (P-max) at 800 degrees C in H-2 shows 41% increment as compared to Sr2TiMoO6. The electrochemical performance of STM0.925O is further enhanced by impregnation of Pd: the R-p is decreased from 0.73 Omega cm(2) to 0.33 Omega cm(2) for STM0.925O and Pd-impregnated STM0.925O (Pd-STM0.925O) anodes, while the corresponding P-max in H-2 increased from 649 to 1051 mW cm(-2) at 850 degrees C. The Pd-STM0.925O shows high electrochemical property and durability in simulated coal syngas containing sulfur (3% H2O), making it a promising anode for hydrocarbon-fueled SOFCs. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.