Mitigating Carbon Formation with Al₂TiO₅-Enhanced Solid Oxide Fuel Cell Anodes

Abstract

Spectroscopic and electrochemical techniques were used to examine the benefits of adding small amounts of aluminum titanate (Al2TiO5 or ALT) to standard NiO–yttria-stabilized zirconia (YSZ)-based solid oxide fuel cell anodes operating with methane at 800 °C. Combining small amounts (4% by mass) of ALT with NiO–YSZ leads to the formation of secondary phases that improve anode carbon tolerance via multiple reaction mechanisms. Raman data show that carbon forms on both ALT-doped and undoped anodes at open-circuit voltage and with applied bias as evidenced by the vibrational band of highly ordered graphite at 1560 cm–1. However, ALT-doped anodes limited the amount of carbon that forms on both the surface and within the bulk, resulting in improved performance for up to 12 h of exposure to CH4. Results show that ALT-enhanced anodes accumulate ∼25% less carbon on the surface under open-circuit conditions and that increasing polarizations to 50% of the maximum current and beyond results in no observable carbon accumulation. These observations are used to deduce possible mechanisms that describe how secondary phases suppress carbon accumulation.

Selective kinetic growth and role of local coordination in forming Al2TiO5-based coatings at lower temperatures

“…Recent studies have also revealed an excellent photocatalytic potential of this material, owing to a moderate band gap (2.88 eV), 68 which has found practical use to improve solid-oxide fuel cells' performances. 69 Still, the challenges concerning the synthesis of this material have restricted its widespread applicability. Solid-state synthesis methods, like sintering, are widely adopted to obtain the Al 2 TiO 5 phase by mixing and heating equimolar ratios of Al 2 O 3 and TiO 2 powders.…”

“…Recent studies have also revealed an excellent photocatalytic potential of this material, owing to a moderate band gap (2.88 eV), 68 which has found practical use to improve solid-oxide fuel cells' performances. 69…”

Operando characterization of metallic and bimetallic electrocatalysts for SOFC fuel electrodes operating under internal methane reforming conditions

“…This procedure has proven effective at rapidly removing carbon from SOFC anodes with minimal degradation to the anode's microstructure from repeated environmental redox cycling. 2,[38][39][40]…”