Coupling Single-Atom Sites and Ordered Intermetallic PtM Nanoparticles for Efficient Catalysis in Fuel Cells

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Proton-exchange membrane fuel cells (PEMFCs) require efficient catalysts for the oxygen reduction reaction (ORR).
• Achieving low platinum (Pt) loading and high stability in acidic ORR catalysts remains a significant challenge for widespread PEMFC adoption.

Purpose of the Study:

• To develop a novel gas-phase ordered alloying strategy for constructing synergistic catalytic systems.
• To integrate Pt-based intermetallic compounds (PtM IMCs) with isolated transition metal sites (M-N4) on nitrogen-doped carbon (NC) supports.

Main Methods:

• A gas-phase ordered alloying strategy was employed using transition metal salts with low boiling points.
• The method facilitates the trapping of metal salts onto Pt nanoparticles and defects on NC supports, preventing aggregation.
• Characterization of the resulting PtM IMCs and M-N4 sites on NC.

Main Results:

• The developed synergistic catalytic system, particularly Pt1Fe1 IMC with Fe-N4 sites, demonstrated a high half-wave potential of 0.94 V for ORR.
• Achieved a mass activity of 0.51 A mgPt−1, exceeding current targets.
• Exhibited excellent stability with only 23.5% decay after 30,000 cycles, surpassing DOE 2025 goals.

Conclusions:

• The gas-phase ordered alloying strategy is effective for creating advanced catalysts for PEMFCs.
• This approach significantly reduces Pt loading while enhancing catalytic performance and durability.
• The integration of Pt-based intermetallics and single transition metal sites offers a promising pathway for next-generation fuel cell catalysts.