Effect of Yttrium-Doped Barium Zirconate on Reactions in Electrochemically Active Zone of Nickel/Yttria-Stabilized Zirconia Anodes

The dependence of electrode performance on the distribution of proton conductor yttrium-doped barium zirconate (BZY) in nickel (Ni)/yttria-stabilized zirconia (YSZ) anodes was investigated to clarify the role of BZY in improving the anode performance in dry methane fuel. In general, electrochemical, decomposition, carbon removal, and reforming reactions occur as anode reactions, and the electrochemical reactions occur only inside the electrochemically active zone of anodes, although the other reactions can also occur outside the electrochemically active zone. To determine the reaction enhanced by BZY addition, BZY was distributed either inside or outside electrochemically active zone of Ni/YSZ anodes by using double-layer anodes consisting of Ni/YSZ and Ni/YSZ/BZY layers. In the Ni/YSZ/BZY layer, BZY was evenly and finely dispersed using a composite powder prepared by spray pyrolysis. The addition of BZY inside the electrochemically active zone improved the anode performance, whereas the addition of BZY outside the electrochemically active zone did not, suggesting that the main role of BZY was to enhance the electrochemical reactions. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.037111jes] All rights reserved.