Ordered Pt₃Co Intermetallic Nanoparticles Derived from Metal-Organic Frameworks for Oxygen Reduction.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Highly ordered platinum (Pt) alloy structures are crucial for enhancing catalytic activity and stability in oxygen reduction reactions (ORR) for proton exchange membrane fuel cells.
• Existing methods for creating these alloys often face challenges in achieving precise structural control and maintaining stability under operating conditions.

Purpose of the Study:

• To develop a facile and effective approach for synthesizing ordered Pt₃Co intermetallic nanoparticles.
• To investigate the role of metal-organic framework (MOF)-derived carbon with atomically dispersed cobalt (Co) sites in forming these ordered structures.
• To evaluate the catalytic performance and stability of the synthesized Pt₃Co catalysts for ORR.

Main Methods:

• Preparation of Pt nanoparticles supported on Co-doped MOF-derived carbon.
• Facile thermal treatment to induce diffusion of atomically dispersed Co sites into Pt nanocrystals, forming ordered Pt₃Co structures.
• Characterization using atomic-scale elemental mapping and electrochemical testing, including accelerated stress tests and fuel cell performance evaluation.

Main Results:

• A new synthesis route successfully produced ordered Pt₃Co intermetallic nanoparticles.
• The optimal catalyst demonstrated significantly enhanced ORR activity (half-wave potential of 0.92 V vs RHE) and exceptional stability, retaining 88% of its performance after 30,000 potential cycles.
• The ordered intermetallic structure was confirmed to be stable under accelerated stress tests.

Conclusions:

• The developed thermal treatment method using Co-doped MOF-derived carbon is an effective strategy for creating highly active and stable ordered Pt₃Co alloy catalysts.
• This approach leverages the unique properties of MOFs, offering a promising pathway for advancing proton exchange membrane fuel cell technology.
• The use of MOF-derived carbon as a source of atomically dispersed Co offers advantages over traditional methods for alloy catalyst preparation.