Double-Perovskite Anode Materials Sr 2 MMoO 6 (M = Co, Ni) for Solid Oxide Fuel Cells
2009; American Chemical Society; Volume: 21; Issue: 11 Linguagem: Inglês
10.1021/cm8033643
ISSN1520-5002
AutoresYun-Hui Huang, Gan Liang, Mark Croft, Matti Lehtimäki, Maarit Karppinen, John B. Goodenough,
Tópico(s)Electronic and Structural Properties of Oxides
ResumoDouble-perovskites Sr2MMoO6 (M = Co, Ni) have been investigated as anode materials for a solid oxide fuel cell. At room temperature, both Sr2CoMoO6 and Sr2NiMoO6 are tetragonal (I4/m). X-ray absorption spectroscopy confirmed the presence of Co2+/Mo6+ and Ni2+/Mo6+ pairs in the oxygen-stoichiometric compounds. The samples contain a limited concentration of oxygen vacancies in the reducing atmospheres at an anode. Reoxidation is facile below 600 °C; they become antiferromagnetic at low temperatures TN = 37 and 80 K for M = Co and Ni, respectively. As an anode with a 300 μm thick La0.8Sr0.2Ga0.83Mg0.17O2.815 electrolyte and SrFe0.2Co0.8O3−δ as a cathode, Sr2CoMoO6 exhibited maximum power densities of 735 mW/cm2 in H2 and 527 mW/cm2 in wet CH4 at 800 °C; Sr2NiMoO6 shows a notable power output only in dry CH4. The high performance of Sr2CoMoO6 in wet CH4 may be due to its catalytic effect on steam reforming of methane, but some degradation of the structure that occurred in CH4 obscures identification of the catalytic reaction processes at the surface. However, the stronger octahedral-site preference of Ni2+ versus Co2+ can account for the lower performance of the M = Ni anode.
Referência(s)