Subsize Pt-based intermetallic compound enables long-term cyclic mass activity for fuel-cell oxygen reduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Platinum-based alloy catalysts show high mass activity for oxygen reduction but lack long-term stability in proton exchange membrane fuel cells (PEMFCs).
• Existing catalysts often suffer from degradation and poisoning in practical fuel cell environments.

Purpose of the Study:

• To develop highly active and durable electrocatalysts for oxygen reduction in PEMFCs.
• To investigate the effect of subsize intermetallic compounds with Pt skin on catalyst performance and stability.

Main Methods:

• Synthesis of subsize Pt-based intermetallic compounds (Pt3Co, PtCo, Pt3Ti) with ultrathin Pt skin (average particle size ~2.3 nm).
• Evaluation of cyclic mass activity and durability for oxygen reduction reactions.
• Assessment of membrane electrode stability under humid fuel cell conditions.

Main Results:

• The subsize Pt-based intermetallic compounds exhibited outstanding cyclic mass activity and durability for oxygen reduction.
• Simultaneous optimization of mass activity and durability was achieved by overcoming size limitations in Pt alloy systems.
• Enhanced membrane electrode stability was observed due to the prevention of catalyst poisoning by ionomers.

Conclusions:

• Subsize Pt-based intermetallic compounds with Pt skin represent a promising design for high-performance oxygen reduction electrocatalysts in PEMFCs.
• Preventing ionomer poisoning is critical for assembling robust commercial membrane electrodes in PEMFCs.