Solid oxide fuel cells with LaSr2Fe2CrO9-δ–Gd0.1Ce0.9O2-δ composite anodes were tested in H2, H2S-contaminated H2, and CH4 fuels as well as under redox cycling conditions. The La0.9Sr0.1Ga0.8Mg0.2O3-δ electrolyte supported cells had La0.4Ce0.6O2-δ barrier layers to prevent cation diffusion between LaSr2Fe2CrO9-δ and La0.9Sr0.1Ga0.8Mg0.2O3-δ. After an initial break-in where the performance improved slightly, the cells were stable in humidified H2 with a power density > 0.4 W cm− 2 and an anode polarization resistance as low as 0.22 Ω cm2. Anode polarization resistance showed little or no change after 15 redox cycles at 800 °C. Cell performance was stable with 22 ppm H2S, with only a slight performance decrease relative to pure H2, but higher H2S concentrations caused continuous degradation. Also, the performance in humidified CH4 fuel was quite low.Highlights► LaSr2Fe2CrO9-δ– GDC anode performance can be improved with a La0.4Ce0.6O2-δ barrier layer. ► LaSr2Fe2CrO9-δ– Gd0.1Ce0.9O2-δ did not degrade after 15 redox cycles. ► LaSr2Fe2CrO9-δ– Gd0.1Ce0.9O2-δ anode performance was poor on CH4.

Compared to traditional deposition techniques, in situ growth of nanoparticles on material surfaces is one of the more time- and cost-effective ways to design new catalysts. The B-site transition-metal cations in perovskite lattice could be partially exsolved as nanoparticles under reducing conditions, greatly enhancing catalytic activity. Here, we demonstrate that growing nanoparticles on the surface of a layered perovskite La0.8Sr1.2Fe0.9Co0.1O4±δ (LSFC), which could be applied as a redox stable and active electrode for intermediate-temperature symmetrical solid oxide fuel cells (IT-SSOFCs). Substitution of a proper amount of Co into the layered perovskite can thus optimize cathode and anode performance simultaneously. For example, the polarization resistances (Rp) of LSFC electrode at 800 °C are 0.29 and 1.14 Ω cm2 in air and in 5% H2/N2 respectively, which are much smaller compared with the Rp of Co-free La0.8Sr1.2FeO4±δ. The lower polarization resistance for LSFC in air can be mainly attributed to the enhanced electrical conductivity through the partial substitution of iron by cobalt in La0.8Sr1.2FeO4±δ. Meanwhile, the electrocatalytic activity of H2 greatly improved, because of the formation of exsolved homogeneous Co0 nanoparticles on the surface of LSFC, which appears to promote hydrogen oxidation reaction. Lower polarization resistance of 0.21 Ω cm2 in air and 0.93 Ω cm2 in 5% H2/N2 at 800 °C could be obtained further by examining an LSFC–Gd0.1Ce0.9O2−δ (CGO) composite as an electrode for IT-SSOFCs.