SOFC anodes based on infiltration of tungsten bronzes

• DOI: 10.1016/j.ijhydene.2011.09.059
• Publication Date: 2011-10-17T14:54:45Z
• Authors: Lawrence Adijanto; Rainer Küngas; Jongsung Park; John M. Vohs; Raymond J. Gorte
• Keywords: Bronze

Abstract Several tungsten bronzes were investigated for use in solid oxide fuel cell (SOFC) anodes. Composite anodes were prepared by infiltration of the precursor salts into a porous yttria-stabilized zirconia (YSZ) scaffold to produce 40-wt% composites with bronze compositions of Na 0.8 Nb y W 1−y O 3−δ ( y = 0, 0.3, 0.7, and 1), K 0.5 WO 3−δ , Cs 0.2 WO 3−δ , and Rb 0.2 WO 3−δ . XRD data showed that the bronze structures were formed following reduction in humidified H 2 at 873 K but that the bronzes were partially reduced to metallic W above 1073 K. Composite conductivities as high as 130 S/cm were observed at 973 K for the Na 0.8 WO 3−δ -YSZ composite but substitution of Nb significantly decreased the conductivity without increasing the temperature at which tungsten was reduced. The impedance of Na 0.8 WO 3−δ -YSZ anodes in humidified H 2 at 973 K was greater than 1.0 Ω cm 2 but this decreased to approximately 0.3 Ω cm 2 upon the addition of 1-wt% Pd for catalytic purposes. The possible use of anodes based on tungsten bronzes is discussed.