Gd2Ti2-XMoXO7-Based Anode Materials for H2S-Air Solid Oxide Fuel Cells

Abstract

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 cm2 at 950oC 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.