Designing SrCo_0.8Fe_0.2O_3−δ-Fe₃O₄ nanocomposite heterostructure enabling high proton conduction for low temperature fuel cell

Abstract

Proton-conducting oxides and protonic ceramic fuel cells (PCFCs) are pivotal in the modern electrochemical energy infrastructure. This study introduces an approach to construct a heterostructure nanocomposite of Fe3O4 grown on the semiconductor SrCo0.8Fe0.2O3 (SCF) to enhance proton conduction. While both SCF and Fe3O4 individually exhibit electronic conduction dominance, the designed heterostructure successfully adjusts the electronic-to-protonic conductivity, resulting in an ionic conductivity of 0.2 S cm−1. Consequently, semiconductor ionic fuel cells (SIFCs) based on the SCF-Fe3O4 nanocomposite as the electrolyte demonstrate excellent performance at 550 °C, exhibiting a power density of 906.875 cmW/cm2. The transition from electronic to protonic conduction in this nanocomposite SCF-Fe3O4 heterostructure is attributed to an energy band alignment mechanism. These results highlight the promising potential of the semiconductor SCF-Fe3O4 heterostructure nanocomposite approach for developing highly efficient proton conductors and enabling the advancement of SIFCs.