Constructing Highly Durable Fuel Cell Catalysts Through Integrating Graphitic Shell-Protected Composite Carbon...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Platinum-cobalt (PtCo) catalysts are crucial for oxygen reduction reactions (ORR) but suffer performance degradation due to metal dissolution, nanoparticle agglomeration, and carbon support corrosion.
• Existing catalysts face challenges in maintaining stability under harsh acidic and oxidative conditions prevalent in electrochemical applications.

Purpose of the Study:

• To design and synthesize high-performance and durable Pt3Co intermetallic catalysts for ORR.
• To improve catalyst stability by addressing metal dissolution, nanoparticle agglomeration, and carbon support corrosion.
• To investigate the role of a novel composite carbon support in enhancing catalyst longevity and performance.

Main Methods:

• A composite carbon support derived from ZIF-8/polyaniline was developed, featuring a high-surface-area (HSC) core and a protective graphitic shell (GS).
• A 40 wt.% Pt/HSC@GS catalyst was synthesized using a strategy involving gaseous Co deposition onto Pt nanoparticles.
• The process facilitated Co diffusion into Pt nanoparticles during annealing to form ordered Pt3Co intermetallic structures, with a protective carbon layer forming on nanoparticles.

Main Results:

• The synthesized Pt3Co intermetallic catalyst on the composite carbon support demonstrated exceptional stability and performance in membrane electrode assemblies (MEAs).
• MEAs maintained high current densities (e.g., 1.09 A cm⁻² at 0.7 V after 10,000 cycles and 1.15 A cm⁻² after 150,000 cycles) with minimal performance loss.
• The catalyst exhibited remarkable durability under heavy-duty conditions, achieving 1.45 A cm⁻² at 0.7 V after 120,000 cycles, significantly outperforming current catalysts.

Conclusions:

• The integrated strategy of using a composite carbon support and gaseous Co deposition effectively produces highly stable and performant Pt3Co intermetallic catalysts.
• The protective graphitic shell and the thin carbon layer formed during synthesis mitigate degradation mechanisms, ensuring long-term catalyst durability.
• This approach offers a promising pathway for developing advanced electrocatalysts for demanding electrochemical applications like fuel cells.