Phosphine impurity tolerance of Sr2MgMoO6-δ composite SOFC anodes

An all-ceramic solid-oxide fuel cell (SOFC) anode composed of a mixture of Sr2MgMoO6-delta (SMM) and Ce0.9Gd0.1O2 (GDC) on a yttrium-stabilized zirconia (YSZ) electrolyte was synthesized and tested in clean and phosphine-contaminated hydrogen and coal syngas. The initial electrochemical performance of the cell at 800 degrees C was 290 mW cm(-2) and 180 mW cm(-2) in wet H-2 and in clean syngas, respectively. The same cell was tested in wet H-2 with 10 ppm PH3, where the cell displayed stable performance over the first 40 h, but then slowly degraded over the next 80 h leading to a 47% decrease in power out-put (0.59 h(-1) %). Although the anode showed notable degradation over the 120 h test, the performance was much improved compared to typical Ni/YSZ cermet anodes. XPS results did not detect P at the anode/electrolyte interface nor throughout the bulk of the anode in either a phosphide or phosphate form. While still unclear, this initial work suggests that degradation of the cell may be due to partial de-lamination of the cell at the anode/electrolyte interface. (C) 2011 Elsevier B.V. All rights reserved.