Breaking the Ion Ordering in the Perovskite Anode for Enhanced High-Temperature Oxygen Evolution Reaction Activity

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Perovskite oxides are crucial for high-temperature applications like solid oxide electrolysis cells (SOECs).
• Ion ordering in perovskites influences magnetic, electronic, ionic, and dielectric properties.
• Perovskites are common anodes for the oxygen evolution reaction (OER) in SOECs, but the effect of ion ordering on OER activity is not well understood.

Purpose of the Study:

• To investigate the impact of A-site ion ordering on the OER activity of PrxB a2-xCo2O5+δ perovskite anodes.
• To correlate ion order-disorder transitions with changes in electronic structure and ionic conductivity.
• To optimize SOEC anode performance by controlling ion ordering.

Main Methods:

• Synthesis and characterization of PrxB a2-xCo2O5+δ perovskites with varying Pr content (x=1.0 to 1.5).
• Comprehensive material characterizations (e.g., structural, spectroscopic).
• Density functional theory (DFT) calculations to understand electronic structure and bonding.
• Electrochemical testing of anode performance in SOECs, including impedance spectroscopy.

Main Results:

• A-site ion ordering in PrxB a2-xCo2O5+δ transitions from ordered to disordered as Pr content increases.
• The order-disorder transition enhances d-p orbital hybridization, improving oxygen exchange and ion transport.
• Disordered Pr1.5Ba0.5Co2O5+δ anodes showed reduced ohmic and polarization resistances.
• Superior OER performance achieved: 2.29 A cm⁻² at 1.6 V and 800 °C for the disordered anode.

Conclusions:

• Ion ordering in perovskite anodes critically affects SOEC performance.
• Disordered perovskite structures enhance OER activity through improved electronic and ionic transport.
• This study provides insights for designing advanced SOEC anode materials by controlling ion ordering.