Gd-doped ceria with extraordinary oxygen-ion conductivity for low temperature solid oxide fuel cells

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Doped ceria is a key electrolyte for solid oxide fuel cells (SOFCs).
• Gadolinia doped ceria (GDC) is particularly studied for low-temperature SOFC applications.
• Optimizing GDC synthesis and understanding its properties are crucial for efficient energy conversion.

Purpose of the Study:

• To synthesize gadolinia doped ceria (GDC) nanoparticles using a co-precipitation method.
• To investigate the structural, morphological, and electrochemical properties of GDC.
• To establish the correlation between oxygen vacancy concentration and ionic conductivity in GDC.

Main Methods:

• Co-precipitation method for GDC nanoparticle synthesis (GdₓCe₁₋ₓO₂₋δ, 0 < x < 0.20).
• X-ray diffraction (XRD) and Raman spectroscopy for phase and defect analysis.
• Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive Spectroscopy (EDS) for morphology and elemental mapping.
• Electrochemical Impedance Spectroscopy (EIS) to determine ionic conductivity at varying temperatures (350-700 °C).

Main Results:

• GDC nanoparticles with a cubic ceria phase and confirmed oxygen vacancies were successfully synthesized.
• FESEM revealed compact grains with ~98% theoretical density.
• GDC doped with 15 mol% Gd³⁺ (Gd₀.₁₅Ce₀.₈₅O₂₋δ) exhibited the highest grain boundary ionic conductivity (0.104 S cm⁻¹ at 700 °C) with an activation energy of 0.81 eV.

Conclusions:

• The co-precipitation method effectively produced dense GDC nanoparticles.
• Gadolinium doping significantly enhances ionic conductivity in ceria by creating oxygen vacancies.
• Optimized GDC composition (15 mol% Gd³⁺) shows promise as an efficient electrolyte for low-temperature SOFCs.