Self-assembled nano-composite perovskites as highly efficient and robust hybrid cathodes for solid oxide fuel cells

Abstract

The oxygen reduction reaction, which proceeds at the cathode of a fuel cell, is primarily important as its rate determines the overall performance of a device. However, designing a single-phase material that meets multiple standards (e.g., high activity, stability, and thermomechanical characteristics) at once to become an ideal cathode still remains a great challenge. In this regard, the use of multi-phase catalysts, especially those with complex nanoscale domains, may serve as a rational strategy. Here, we present Ba0.5Sr0.5Co0.6Fe0.2Zr0.1Y0.1O3-delta (BSCFZY) as a superior biphasic nano-composite cathode, which self-assembles into two discrete cubic perovskites: Co-rich (Ba0.5Sr0.5Co0.7Fe0.2Zr0.07Y0.03O3-delta) and Zr-rich (Ba0.6Sr0.4Co0.3Fe0.2Zr0.4Y0.1O3-delta) phases. The former promotes the electrocatalytic activity while the latter supports the microstructural robustness; thus, the synergic ensemble of Co- and Zr-rich perovskite domains yields an area specific resistance of only similar to 0.013 omega cm(2) at 650 degrees C, which is far superior to that anticipated from the component phases in isolation. The cooperative interaction found in multi-phase catalysts prepared via a simple one-pot synthesis is not only attractive for SOFCs but also for other kinds of energy conversion and storage devices, such as protonic ceramic electrochemical cells, electrolysers, and membrane chemical reformers.