Amorphous oxide Gd-alumina electrolyte for low-temperature ceramic fuel cells

The demand for highly ion-conductive materials, predominantly amorphous, is crucial in designing advanced low-temperature ceramic fuel cells (LT-CFCS). The reasons for the higher ionic conductivity of amorphous oxides remain a topic of intense debate in the literature. A comprehensive understanding is needed to optimize its use and advance CFC development. Herein, we design an appealing amorphous electrolyte, Gd-alumina, to investigate the ionic and proton conduction at 550°C-425 °C. The amorphous 20% Gd-alumina sample exhibits a high ionic conductivity of 0.25 S/cm and an impressive power density of 1020 mW/cm² at 550 °C. The disordered atomic structure of amorphous Gd-alumina and non-oriented grain boundaries (GB) induce the oxygen vacancies (O_v), reduce energy barriers, and enhance ionic mobility, enabling effective ionic and protonic conduction at the surface of Gd-Alumina. Various characterization, including XRD (X-ray diffraction), SEM, HR-TEM (scanning and transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), and TGA (Thermogravimetric analysis), revealed that the prepared amorphous Gd-alumina possesses promising structural, morphological, and electrical properties, making it an excellent electrolyte for LT-CFCs. Finally, our study explores the ionic transport pathways, demonstrating how the disorder atomic configuration in amorphous oxide enhances the ions and proton transport. These findings reveal that Gd-alumina is a promising amorphous oxide (AO) capable of functioning as an excellent electrolyte, paving the way for innovative design of amorphous materials in LT-CFCs.