Electrokinetic Proton Transport in Triple (H+/O2-/e-) Conducting Oxides as a Key Descriptor for Highly Efficient Protonic Ceramic Fuel Cells

Recently, triple (H+/O2-/e(-)) conducting oxides (TCOs) have shown tremendous potential to improve the performance of various types of energy conversion and storage applications. The systematic understanding of the TCO is limited by the difficulty of properly identifying the proton movement in the TCO. Herein, the isotope exchange diffusion profile (IEDP) method is employed via time-of-flight secondary ion mass spectrometry to evaluate kinetic properties of proton in the layered perovskite-type TCOs, PrBa0.5Sr0.5Co1.5Fe0.5O5+delta (PBSCF).Within the strategy, the PBSCF shows two orders of magnitude higher proton tracer diffusion coefficient (D*(H), 1.04 x 10(-6) cm(2) s(-1) at 550 degrees C) than its oxygen tracer diffusion coefficient at even higher temperature range (D*(O,) 1.9 x 10(-8) cm(2) s(-1) at 590 degrees C). Also, the surface exchange coefficient of a proton (k*(H)) is successfully obtained in the value of 2.60 x 10(-7) cm s(-1) at 550 degrees C. In this research, an innovative way is provided to quantify the proton kinetic properties (D*(H) and k*(H)) of TCOs being a crucial indicator for characterizing the electrochemical behavior of proton and the mechanism of electrode reactions.

Automated summary

Triple conducting oxides (TCOs) have shown great potential in energy conversion and storage applications, and understanding their proton movement remains a challenge. This study utilized the isotope exchange diffusion profile method to evaluate proton kinetic properties in the layered perovskite-type TCO PBSCF, revealing significantly higher proton diffusion coefficient compared to oxygen at elevated temperatures. The research provides an innovative way to quantify proton kinetic properties in TCOs, which is crucial for understanding their electrochemical behavior and electrode reaction mechanisms.