The Gd2Ti2-xMoxO7 (x = 0.2, 0.6, and 1.0) pyrochlore solid solutions have been investigated as anode materials for solid oxide fuel cells (SOFCs) powered by H2S- containing gases. While the total electrical conductivity increases with Mo content in reducing atmospheres, the chemical stability in H2 containing 10% H2S is insufficient at high Mo content (x = 1.0 in Gd2Ti2-xMoxO7). Lowering the Mo content to x = 0.6 allows the anode to become chemically stable while retaining high electrical conductivity in H2S-containing atmospheres. The fuel cells based on Gd2Ti1.4Mo0.6O7 anode material show remarkable electrochemical performance. The anode/electrolyte interfacial resistance was 0.2 Ω cm2 at 950°C in a fuel gas mixture of 10%H2S/3%H2O/87%H2, resulting in a peak power density of 342 mW cm-2. This fuel cell also performs well when fed with 10%H2S balanced by N2. The analysis of effluent gas shows that H2S was predominantly converted to elemental sulfur. The Gd2Ti1.4Mo0.6O7 anode based SOFCs have great potential to operate directly on H2S feedstock to produce high electrical energy as well as useful sulfur by-product. copyright The Electrochemical Society.
