Pd-impregnated Sr1.9VMoO6–δ double perovskite as an efficient and stable anode for solid-oxide fuel cells operating on sulfur-containing syngas

Abstract

The development of carbon- and sulfur-tolerant anode materials is highly desirable for the commercial application of solid-oxide fuel cells (SOFCs). We report herein the performance of Sr1.9VMoO6−δ (SVMO) double perovskite as a potential anode material for SOFCs and the improvement of its electrochemical performance on hydrogen and H2S-containing syngas operation. SVMO has a cubic structure and thermal expansion coefficient of 13.3 × 10−6 K−1 between 30 and 1000 °C in 5% H2/Ar. The electrical conductivities of SVMO in H2 are considerably higher than those of existing double-perovskite anodes and traditional Ni–YSZ (40 vol% Ni) anode. The impregnation of Pd nanoparticles to form a composite anode (Pd–SVMO) or the addition of a Ce0.8Sm0.2O1.9 buffer layer between anode and electrolyte significantly improves the electrochemical performance of SVMO for hydrogen oxidation, and the former is considerably more effective than the latter. The Pd–SVMO composite anode exhibits good stability and resistance to carbon deposition and sulfur poisoning for an SOFC operated on H2S-containing syngas based on an 80 h test, suggesting the potential of this anode material for SOFCs running on hydrocarbon fuels. The mechanisms for improving the electrochemical performance of the anodes and the resistance to carbon deposition and sulfur poisoning are also discussed.