Synthesis of Ru-doped Double Perovskite Anode for SOFC

Abstract

One of the great current needs for anode material in solid oxide fuel cells is to combine in one redox-resistant compound an efficient multifunctionality, that is, that the same material must exhibit both good catalytic activity and mixed ionic-electronic conductivity. Such a material should ideally be active towards different fuels allowing fuel-flex SOFCs capable to operate using the most convenient fuel available in various situations. Ceramics with perovskite structure are, from this point of view, are promising candidates. Different compounds such as (La,Sr)(Mn,Cr)O and SrMoMgO have been investigated, but more efficient anodes are still required. In this study, the Pr0.5Ba0.5MnO3 was used as the precursor phase of the double perovskite PrBaMn2O5+δ (PBMO), obtained at reducing conditions. The transport and catalytic properties were studied in the pristine compound and in Ru-doped samples Pr0.5Ba0.5Mn1-xRuxO3 (Ru-PBMO). Ru substitution at the B-site is expected to enhance the catalytic properties of the ceramic toward ethanol or methane fuels. Ceramic powders were synthesized by the polymeric precursor method and characterized by thermogravimetric analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical properties of sintered samples were evaluated by dc 4-probe technique, in the 25 - 800 °C temperature range in both air and reducing conditions. The TG/DTA and XRD data show mass loss stabilization and crystalline phase formation occurring at ~800 °C. The evolution of the XRD pattern upon calcining temperature indicated the formation of single phase of Ru-PBMO samples at ~1100 °C. The initial results suggest that PBMO and PBMO-Ru compounds are promising SOFC anodes.