Harnessing Controlled Dealloying-Support Coupling for Ultrastable PtNi Catalysts in PEMFC Applications

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Platinum-transition metal (PtM) alloys are key oxygen reduction reaction (ORR) catalysts for proton-exchange membrane fuel cells (PEMFCs).
• Challenges include transition metal dissolution, particle coarsening, and poor durability, often worsened by aggregation in conventional strategies.

Purpose of the Study:

• To develop a durable and high-performance PtNi catalyst for PEMFCs.
• To overcome limitations of traditional alloying methods by preventing nanoparticle aggregation and enhancing stability.

Main Methods:

• A controllable alloying-dealloying strategy was employed to create PtNi nanoparticles confined within an N-doped carbon framework (Pt1Ni1-x@Nix_NC).
• Ammonia-assisted dealloying created a Pt-rich shell and alloyed core, with released Ni atoms anchored by the N-doped carbon as Ni-N/C moieties.
• This coordination-support coupling was analyzed for its effect on electronic structure and ORR kinetics.

Main Results:

• The Pt1Ni1-x@Nix_NC catalyst achieved a high half-wave potential of 0.932 V and a mass activity of 2.028 A mgPt−1, 8.75 times higher than commercial Pt/C.
• Exceptional durability was demonstrated with only a 6 mV half-wave potential loss after 30,000 cycles.
• In PEMFCs, the fuel cell reached a peak power density of 975 mW cm−2 and maintained 91.9% of its initial performance.

Conclusions:

• The alloying-dealloying strategy effectively suppresses agglomeration and enhances metal-support interactions, optimizing ORR kinetics.
• This approach provides a generalizable method for designing durable, high-performance, low-platinum group metal (PGM) catalysts for next-generation PEMFCs.