A highly efficient composite cathode for proton-conducting solid oxide fuel cells

Abstract

To develop highly efficient cathode materials can accelerate the commercial application of proton conducting solid oxide fuel cells (PCFCs). In this study, we fabricated highly efficient triple-conducting composite oxides using single- and double-layered perovskites. Compared to the cell performance of single- and double-layered perovskites, these triple-conducting composite oxides have better oxygen reduction capabilities and a robust structure showing a peak power density of 1.57 W cm−2 and an ASR of 0.021 Ω cm2 at 750 °C. No phase reactions or structural changes were found between the Sm0.5Sr0.5CoO3−δ (SSC) and the SmBaCo2O5+δ (SBC) composites, as detected through in-situ high temperature X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM) techniques. Density functional theory (DFT) calculations revealed that the interfacial electron transfers and redistributions between SSC and SBC were beneficial for electron-hole separation. Therefore, such bond destabilization inevitably increased the energy of the occupied π∗ orbitals originating from the surface-peroxo species in the tensile-strained interface, enhancing the bulk and surface diffusivities of the oxide ions to improve oxygen reduction reactions. This work provides a simple yet easily replicable method for designing more efficient and stable catalysts for use in PCFC applications.