The enhanced electrochemical response of Sr(Ti0.3Fe0.7Ru0.07)O3
d anodes due to exsolved Ru?Fe nanoparticles

R. GLAZER; T. ZHU; H. TROIANI; A. CANEIRO; L. MOGNI; S. BARNETT

Journal of Materials Chemistry A

Royal Society of Chemistry

Año: 2018

2050-7488

A mixed conducting oxide with a nominal composition Sr(Ti0.3Fe0.7Ru0.07)O3d (STFRu) is studied, incomparison with SrTi0.3Fe0.7O3d (STF) oxide, as an anode for solid oxide fuel cells. Exposing STFRu toreducing fuel conditions at 800 C for 4 h results in the exsolution of essentially all of the Ru and a smallfraction of the Fe from the oxide, and the formation of Ru1xFex nanoparticles on the oxide surfaces.Most of the nanoparticles have the hexagonal structure expected for Ru-rich alloys, andthermogravimetric analysis suggests the composition x 0.2. A small fraction of bcc-structure,presumably Fe-rich, nanoparticles are also detected. Comparison of cells with STFRu and STF anodesshows that the presence of Ru induces a reduced polarization resistance and increases the maximumpower density under most cell operating conditions, particularly at lower temperatures and hydrogenpartial pressures. For example, at 700 C and 30% H2 fuel, the maximum power density is 0.1 W cm2 forSTF compared to 0.3 W cm2 for STFRu. There is also a significant change in the shape of the current?voltage curves and the pH2-dependence of the anode polarization resistances RP,A f (pH2)m, from m 0.5?1.0 for STF to m 0.11?0.29 for STFRu; these suggest that Ru1xFex nanoparticles improve anodeperformance by promoting hydrogen adsorption.