New SrMo1−xCrxO3−δ perovskites as anodes in solid-oxide fuel cells (original) (raw)

2014, International Journal of Hydrogen Energy

Oxides of composition SrMo 1Àx Cr x O 3Àd (x ¼ 0.1, 0.2) have been prepared, characterized and tested as anode materials in single solid-oxide fuel cells, yielding output powers higher than 700 mW cm À2 at 850 C with pure H 2 as a fuel. All the materials are suggested to present mixed ioniceelectronic conductivity (MIEC) from neutron powder diffraction (NPD) experiments, complemented with transport measurements; the presence of a Mo 4þ /Mo 5þ mixed valence at room temperature, combined with a huge metal-like electronic conductivity, as high as 340 S cm À1 at T ¼ 50 C for x ¼ 0.1, could make these oxides good materials for solid-oxide fuel cells. The magnitude of the electronic conductivity decreases with increasing Cr-doping content. The reversibility of the reductioneoxidation between the oxidized Sr(Mo,Cr)O 4Àd scheelite and the reduced Sr(Mo,Cr)O 3 perovskite phases was studied by thermogravimetric analysis, which exhibit the required cyclability for fuel cells. An adequate thermal expansion coefficient, without abrupt changes, and a chemical compatibility with electrolytes make these oxides good candidates for anodes in intermediate-temperature SOFC (IT-SOFCs).