Optimizing strontium titanate anode in solid oxide fuel cells by ytterbium doping<bold> </bold>

One of advantages of solid oxide fuel cells (SOFCs) is able to utilize various hydrocarbon fuels. Whereas, the classical Ni anode suffers severe carbon deposition especially operated under CH4. Strontium titanate (SrTiO3) perovskite anodes with strong carbon deposition resistance and good structural stability have been extensively investigated. In this work, Sr0.88Y0.08-xYbxTiO3 and Sr0.88Y0.08Ti1-xYbxO3 are synthesized by Yb3+ doping in A-site and B-site of Sr0.88Y0.08-xYbxTiO3 perovskite, respectively. XRD results confirm that the SrTiO3 cubic perovskite phase is formed in all the samples. Among the Yb3+ doping samples, Sr0.88Y0.08-xYbxTiO3 exhibits the lowest thermal expansion coefficient (11.48 x 10(-6)/K), indicating the best compatibility with the electrolyte. The ionic conductivity of Sr0.88Y0.08-xYbxTiO3 can be improved by proper Yb3+ doping both in A-site and B-site, and the Sr0.88Y0.08-xYbxTiO3 sample has the highest ionic conductivity among all the samples. The maximum power density of SOFC with Sr0.88Y0.08-xYbxTiO3 anode is 87 mW/cm(2) under CH4 at 800 degrees C, which is much higher than that with Sr0.88Y0.08-xYbxTiO3 and Ni anode. This can be related to its high electrocatalytic activity to CH4 oxidation. In addition, SOFC with the Sr0.88Y0.08-xYbxTiO3 anode shows a superior stability operated under CH4 due to the strong carbon deposition resistances. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.