Mo Dopant-Mediated Oxygen Vacancy Engineering for Enhanced Cathodic Activity in Protonic Ceramic Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Protonic ceramic fuel cells (PCFCs) offer lower operating temperatures than solid oxide fuel cells (SOFCs).
• Layered double perovskites like PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ (PBSCF) show promise as triple-conducting (H⁺/O^2-/e^-) cathodes.
• Optimizing cathode performance is crucial for advancing PCFC technology.

Purpose of the Study:

• To investigate the effect of molybdenum (Mo) doping on PBSCF cathode materials for PCFCs.
• To enhance oxygen reduction reaction (ORR) kinetics and overall cell performance.
• To elucidate the mechanism of Mo doping using experimental and theoretical methods.

Main Methods:

• Synthesis and characterization of Mo-doped PBSCF (PBSCFM01).
• Electrochemical testing including polarization resistance (R_p) and peak power density (PPD) measurements.
• Electrical conductivity measurements and density functional theory (DFT) calculations.

Main Results:

• Mo doping significantly reduced R_p by 75% and increased PPD by 44% in PBSCFM01 cells.
• PBSCFM01 exhibited a 15% higher maximum electrical conductivity (1051 S/cm at 250 °C) compared to pure PBSCF.
• DFT calculations confirmed Mo doping promotes oxygen vacancy formation and enhances cathodic activity.

Conclusions:

• High-valence Mo doping is an effective strategy to improve oxygen vacancy formation and ORR kinetics in PBSCF cathodes.
• Mo-doped PBSCF demonstrates superior electrochemical performance, making it a promising cathode material for PCFCs.
• This study provides atomic-level insights into Mo's role in enhancing cathode material performance for fuel cells.