Characterization of Cu-impregnated Sr2-xMgMoO6-6 composite ceramic anode for SOFCs

Sr-deficient Sr2-xMgMoO6-delta (SMMx) (x = 0.00-0.25) double perovskites were prepared using the sol-gel process. XRD results indicate that the x = 0.00-0.15 samples are pure phases with good redox stability, while trace SrMoO4 impurity was detected for the samples with x >= 0.20. XPS analysis demonstrates that Mo5+ content increases monotonously with Sr-deficiency, and the increasing number of Mo5+/Mo6+ redox pairs enhances electrical conductivity with increasing x. Among the SMMx compositions, the SMM0.15 anode exhibits optimal electrochemical performance, with polarization resistance attaining a minimum of 0.36 and 0.59 omega cm(2) in H-2 and CO, respectively, at 850 C-degrees. Using SMM0.15 as the anode skeleton, Cu nanoparticles were loaded onto the skeleton surface via nitrate impregnation. The resulting Cu-impregnated SMM0.15 composite anodes exhibited significantly improved electrical and electrochemical properties. Peak power densities of a single cell supported by a 300-mu m-thick La0.9Sr0.1Ga0.8Mg0.2O3-delta electrolyte and a twice Cu-impregnated SMM0.15 composite anode achieve 933 mW cm(-2) in H-2 and 415 mW cm-2 in CO at 850 C-degrees. The electrochemical reactions at the anode were mainly dominated by fuel diffusion and adsorption/disassociation, particularly for CO. The good cell stability in both H-2 and CO further demonstrates that Cu-impregnated SMM0.15 has great potential as an anode candidate for SOFCs.