Compositional engineering of perovskite oxides for highly efficient oxygen reduction reactions

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Mixed conducting perovskite oxides are crucial catalysts for high-temperature oxygen reduction reactions.
• Strontium cobalt oxide (SrCoO(3-δ)) is a key parent material, but its properties can be improved through doping.
• Existing research often relies on experimental data, lacking universal guidelines for doping strategies.

Purpose of the Study:

• To investigate the fundamental effects of B-site doping concentration with a redox-inactive cation (Sc) on SrCoO(3-δ) perovskite properties.
• To establish universal guidelines for optimizing mixed conducting perovskites through doping.
• To understand the relationship between doping, structure, and electrochemical performance.

Main Methods:

• Combined experimental characterization (phase structure, conductivity, defect chemistry, reaction kinetics, ion transport, electrochemical reactivity).
• First-principles calculations to analyze the impact of doping levels.
• Systematic evaluation of various Sc doping concentrations in SrCoO(3-δ).

Main Results:

• SrCo0.95Sc0.05O(3-δ) exhibited the best oxygen reduction reaction kinetics.
• This composition corresponds to the minimum Sc fraction required to stabilize an oxygen-vacancy-disordered structure.
• Doping significantly influences electronic conductivity, defect chemistry, and oxygen transport properties.

Conclusions:

• B-site doping of SrCoO(3-δ) with small amounts of redox-inactive cations like Sc is an effective strategy.
• This approach leads to highly active mixed conducting perovskites.
• The findings support the development of improved catalysts for solid oxide fuel cells and oxygen transport membranes.