Semiconductor Heterostructure (SFT–SnO₂) Electrolyte with Enhanced Ionic Conduction for Ceramic Fuel Cells

Electronic conduction inhibition, heterostructure construction, constituting built-in electric field (BIEF), and the generation of an energetically more active region in the lattice and at the interface are ways to increase the ionic conductivity (σ i ) of electrolyte materials for ceramic fuel cells (CFCs). The conduction of ions and stoppage of e – conductivity are of utmost importance in semiconductor-based electrolytes. Type-II heterojunction can be synthesized to improve fuel cell performance by increasing ionic conductivity. SFT (SrFe 0.3 Ti 0.7 O 3 )–SnO 2 p–n heterojunction was produced by combining p-type SFT and n-type SnO 2 semiconductors. The resulting SFT–SnO 2 heterostructure unveiled a high ionic conductivity of 0.18 S/cm and an open-circuit voltage (OCV) of 1.04 V, contributing to a remarkable power output of 805 mW/cm 2 at a low operating temperature of 520 °C. High ionic conductivity and efficient fuel cell performance are attributed to a synergistic interaction between the SFT/SnO 2 heterojunction and BIEF. Heterojunction production between SFT and SnO 2 was confirmed by numerous characterization techniques (X-ray diffractometer (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), UV–visible, ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS)). The SFT/SnO 2 junction valence band deviation and energy band structure were also validated. Our research shows that the constructed heterostructure SFT–SnO 2 is an effective and efficient electrolyte material for future fuel cell technology.