In Situ Growth of Nanoparticles in Layered Perovskite La0.8Sr1.2Fe0.9Co0.1O4−δ as an Active and Stable Electrode for Symmetrical Solid Oxide Fuel Cells

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.