Controlled Synthesis of Octahedral Platinum-Based Mesocrystals by Oriented Aggregation.

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Noble metal mesocrystals are crucial for advanced applications.
• Controlled synthesis of alloy mesocrystals remains challenging.
• Understanding structure-property relationships is key for catalysis.

Purpose of the Study:

• To develop a controlled synthesis method for octahedral Pt-Ag alloy mesocrystals.
• To investigate the role of bromide in morphology control.
• To evaluate the electrocatalytic performance of the synthesized mesocrystals.

Main Methods:

• Designed synthesis involving oriented aggregation of crystallites.
• Utilizing bromide as a key regulator for morphology.
• Controlling mesocrystal size by adjusting seed concentration.
• Characterization of morphology, size, and exposed facets.

Main Results:

• Successfully synthesized octahedral Pt-Ag alloy mesocrystals with controlled morphology and size.
• Identified bromide's critical role in achieving octahedral shape.
• Demonstrated precise size control over a broad range.
• Obtained mesocrystals exposing {111} facets with high reproducibility.

Conclusions:

• A controllable and reproducible synthesis route for octahedral Pt-Ag mesocrystals was established.
• The synthesized Pt-Ag mesocrystals exhibit superior electrocatalytic activity and stability for oxygen reduction reactions (ORR).
• This work provides insights for designing diverse faceted nanocrystals/mesocrystals for catalysis.