Double Confinement Design to Access Highly Stable Intermetallic Nanoparticles for Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane fuel cells (PEMFCs) require highly stable low platinum (Pt) catalysts for prolonged operation.
• Maintaining catalyst stability, particularly for intermetallic nanoparticles, is a significant challenge in PEMFC technology.

Purpose of the Study:

• To develop a novel double confinement design to enhance the stability of intermetallic nanoparticles for PEMFCs.
• To maintain high catalytic activity while improving the durability of Pt-based catalysts.

Main Methods:

• A double confinement strategy involving a carbon shell and Pt-skin formation was employed.
• Oxygen (O2) was introduced during annealing to etch the carbon shell and induce surface transition metal segregation.
• The strategy was applied to synthesize double-confined Pt1Co1, Pt1Fe1, and Pt1Cu1 intermetallic nanoparticles.

Main Results:

• The double confined Pt1Co1 catalyst demonstrated excellent mass activity (1.45 A mgPt-1 at 0.9 V) and remarkable stability with only 17.3% decay after 30,000 cycles.
• No structural changes were observed in the double-confined catalysts, indicating superior durability.
• The carbon confinement proportion could be tuned by adjusting the carbon shell thickness.

Conclusions:

• The double confinement design effectively protects intermetallic nanoparticles against harsh PEMFC environments.
• This approach significantly enhances catalyst stability and performance, outperforming existing PtCo catalysts and meeting DOE 2025 targets.
• The synthesis strategy is versatile and applicable to other intermetallic compositions like PtFe and PtCu.