Characteristics of Sr0.92Y0.08Ti1-yNiyO3-delta anode and Ni-infiltrated Sr0.92Y0.08TiO3-delta anode using CH4 fuel in solid oxide fuel cells

摘要

Strontium titanium oxide co-doped with yttrium and nickel (SrxYl-xTiyNi1-yO3-delta; hereafter, SYTN), was investigated as an alternative anode material for solid oxide fuel cells. To improve the ionic conductivity of the Sr0.92Y0.08TiO3-delta (SYT) anode, Ni2+ was substituted into the B-site (initially occupied by Ti4+), thereby forming oxygen vacancies. To analyze the effects of Ni-doping in the SYT anode, the electrochemical properties of the SYTN anode were compared with those of the Ni-infiltrated SYT(Ni@SYT) using H-2 and CH4 as fuels. The electrochemical reactions at the SYTN anode in the presence of both H-2 and CH4 were limited by relatively slow reactions, such as non-charged processes including oxygen surface exchange and solid surface diffusion. The high electrical conductivity and excellent catalytic activity of the Ni nanoparticles in the Ni@SYT anode led to improved cell performance. CH4 decomposition at the Ni@SYT anode occurred via thermal pyrolysis of CH4 rather than by steam methane reforming, resulting in carbon deposition. In comparison, the poor inherent catalytic activity for CH4 oxidation exhibited by the SYTN anode minimized carbon deposition on the anode surface. (C) 2017 Elsevier B.V. All rights reserved.