Rational Design of Perovskite-Based Anode with Decent Activity for Hydrogen Electro-Oxidation and Beneficial Effect of Sulfur for Promoting Power Generation in Solid Oxide Fuel Cells.

Abstract

The poor sulfur tolerance of conventional nickel cermet anodes is particularly concerning for solid oxide fuel cell technology. Herein, we report an innovative anode composed of a samaria-doped ceria (SDC) scaffold and a perovskite La0.35Ca0.50TiO3-d thin film with a surface modified with strongly coupled and in situ-formed Ni nanoparticles; the anode was prepared via an infiltration-calcination-reduction method. The rational design of such an anode transforms the detrimental effect of sulfur on the cell performance (poisoning) of state-of-the-art Ni cermet anodes into a beneficial effect promoting power generation from H2. A cell with a Ni + SDC cermet anode and a Ba0.5Sr0.5Co0.8Fe0.2O3-d cathode showed an 18.3% reduction in the power output at 800 °C when the fuel gas was switched from pure H2 to H2-1000 ppm H2S, while a similar cell with this innovative anode showed a power output enhancement of 6.6%. Furthermore, the operational stability was significantly improved. The perovskite phase was found to account for the improved cell power output in the presence of sulfur impurity. The introduction of the nickel nanoparticles further significantly enhanced the electrode activity, while the strong coupling effect of exsolved nickel nanoparticles with the perovskite thin film improved the sulfur tolerance of the nickel phase. As a result, the anode showed both high activity and stability while operating on H2 fuel with high concentration of H2S (1000 ppm). The promoting effect of sulfur on the power generation over the perovskite anode is also discussed.