The fabrication of a highly conductive ceria-embedded gadolinium-stabilized bismuth oxide nanocomposite solid electrolyte for low-temperature solid oxide fuel cells

Abstract

We report the synthesis of a nanocomposite solid electrolyte, (1 − x)Bi₂O₃–Gd₂O₃:xCeO₂ (GDBC), made up of ceria-embedded gadolinium-stabilized bismuth oxide (Bi₂O₃–Gd₂O₃, GDB) for low-temperature solid oxide fuel cell (LT-SOFC) applications. Different compositions of (1 − x)Bi₂O₃–Gd₂O₃:xCeO₂ (where 0 ≤ x ≤ 50 wt%) were fabricated using a solid-state method. Detailed structural analysis of the nanocomposite solid electrolyte samples was done using SEM, TEM, XRD, and FT-IR techniques. The incorporation of CeO₂ nanofiller enhances the ionic conductivity relative to Bi₂O₃–Gd₂O₃ nanocomposite solid electrolyte via creating new routes for oxygen-ion conduction within the parent network. Among the different compositions of nanocomposite material, GDBC with 40 wt% CeO₂ nanofiller shows the maximum ionic conductivity, i.e., σ = 7.56 × 10⁻² S cm⁻¹, and lowest activation energy (0.0954 eV) at low temperature (340 °C). Notably, challenges preventing the commercialization of LT-SOFCs include material conductivity, safety, and production costs. Hence, this superionic nanocomposite solid electrolyte with 40 wt% CeO₂, having high conductivity at low temperature and low cost, could be a promising candidate for the fabrication of electrolytes for fuel-cell applications.