A Superior Catalytic Air Electrode with Temperature-Induced Exsolution toward Protonic Ceramic Cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Protonic ceramic cells offer potent and environmentally benign energy conversion.
• Limited catalytic activity in air electrode materials hinders performance.
• Developing advanced air electrode materials is crucial for efficient protonic ceramic cells.

Purpose of the Study:

• To synthesize SrCo_0.5Nb_0.5O_3-δ (SCN) nanoparticles on PrSrCo_1.8Nb_0.2O_6-δ (PSCN) via temperature-induced exsolution.
• To investigate the impact of SCN nanoparticles on the catalytic activity of PSCN for proton-involved reactions.
• To evaluate the performance of a protonic ceramic cell utilizing the SCN-PSCN composite air electrode.

Main Methods:

• Temperature-induced exsolution to synthesize SCN nanoparticles on PSCN.
• In situ assessments to observe exsolution and stability.
• Fabrication and testing of a fuel-electrode-supported protonic ceramic cell.
• Density functional theory (DFT) calculations to analyze reaction mechanisms.

Main Results:

• SCN nanoparticles exsolve from the PSCN matrix above 900 °C and remain stable.
• The SCN-PSCN interface enhances vapor adsorption and protonation, improving surface reaction kinetics.
• The protonic ceramic cell achieved a peak power density of 1.30 W·cm^-2 (fuel cell) and 1.91 A·cm^-2 at 1.3 V (electrolysis) at 650 °C.
• DFT calculations confirmed accelerated electrode reaction rates due to reduced energy barriers for oxygen and vapor dissociation.

Conclusions:

• The exsolution of SCN nanoparticles significantly enhances the catalytic activity of PSCN for proton-involved oxygen reduction and evolution reactions.
• The developed SCN-PSCN composite is a promising air electrode material for high-performance protonic ceramic cells.
• This approach effectively addresses the challenge of limited catalytic activity in conventional air electrode materials.