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

Abstract

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 (σi) 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 (SrFe0.3Ti0.7O3)–SnO2 p–n heterojunction was produced by combining p-type SFT and n-type SnO2 semiconductors. The resulting SFT–SnO2 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/cm2 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/SnO2 heterojunction and BIEF. Heterojunction production between SFT and SnO2 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/SnO2 junction valence band deviation and energy band structure were also validated. Our research shows that the constructed heterostructure SFT–SnO2 is an effective and efficient electrolyte material for future fuel cell technology.