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Boosting ion transport in ceria electrolytes via electronic state passivation for protonic ceramic fuel cells
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DOI：10.1016/j.jechem.2026.07.044.png)
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Abstract
En 中文
Low-temperature protonic ceramic fuel cells (LT-PCFCs) are promising for the hydrogen economy but are fundamentally limited by sluggish ion transport in reducible oxides, arising from defect-induced localized electronic states that act as electrostatic scattering centers. Herein, we propose and demonstrate an electronic state passivation (ESP) strategy, validated by uniformly rare-earth (RE)-passivated ceria-based oxides synthesized via the sol-gel method, compared with defective CeO2−δ. Combined density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectroscopy results find that defect-associated electrons localized at Ce3+ sites generate gap states, acting as electrostatic scattering centers that impede ion transport. The substitution of RE3+ passivates these defect states via charge compensation, which is verified by X-ray photoelectron spectroscopy (XPS) and theoretical calculations, effectively removing gap states as directly observed by EPR spectroscopy and DFT calculations, thus revealing an obvious passivation effect. RE3+ passivation allows calculated ion migration energy barriers to reduce from 1.3 to ∼0.5 eV. Electrochemically, the peak power density of the fuel cell increases from 510 mW cm−2 (CeO2−δ) to 1100 mW cm−2 (La0.1Ce0.9O2−δ), with ionic conductivity enhanced to 0.49 S cm−1 at 520 °C, consistent with the theoretical results. This work establishes ESP as a general design principle for regulating defect-induced electronic states in reducible oxide electrolytes.
Keywords:
Low-temperature protonic ceramic fuel cells (LT-PCFCs)
Electrolyte
Passivation
Rare earth
Ceria (CeO2)
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