Tailoring manganese oxide with atomic precision to increase surface site availability for oxygen reduction catalysis

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Controlling catalyst atomic structure is key to understanding form-to-function relationships and creating novel catalytic materials.
• La_2/3Sr_1/3MnO₃ is a known catalyst for the oxygen reduction reaction (ORR).
• Strontium manganite (SrMnO₃) enhances ORR through electronic structure and conductivity, but can degrade in air, reducing active sites.

Purpose of the Study:

• To investigate the use of advanced thin-film deposition for atomic-level control of La_2/3Sr_1/3MnO₃ catalyst structure.
• To tailor the surface and sub-surface atomic structure of the catalyst while keeping the bulk composition constant.
• To enhance ORR performance by optimizing catalyst structure for improved surface site availability and electronic effects.

Main Methods:

• Utilized advanced thin-film deposition techniques to precisely control the atomic structure of La_2/3Sr_1/3MnO₃.
• Customized the surface and sub-surface atomic arrangement.
• Maintained constant overall composition and d-electron configuration of the oxide.

Main Results:

• Demonstrated successful atomic-level customization of the catalyst's surface and sub-surface structure.
• Showcased that placing SrMnO₃ in the sub-surface beneath a LaMnO₃ overlayer preserves surface site availability.
• Achieved improved electronic effects and conductivity beneficial for the oxygen reduction reaction.

Conclusions:

• Advanced thin-film deposition is a powerful tool for creating atomically precise catalysts.
• Tailoring surface and sub-surface structure and stoichiometry offers superior functionality compared to controlling only bulk composition.
• This approach enables the realization of new, non-equilibrium catalytic structures with enhanced performance.