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 Omega cm(2) at 750 degrees C. No phase reactions or structural changes were found between the Sm0.5Sr0.5CoO3-delta (SSC) and the SmBaCo2O5+delta (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 pi* 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.