Efficient oxygen reduction catalysis by subnanometer Pt alloy nanowires.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Platinum (Pt) and its alloys are crucial catalysts for the oxygen reduction reaction (ORR).
• Small nanoparticles (<2 nm) of Pt alloys are generally considered less effective for ORR.
• Scalable synthesis methods for sub-nanometer Pt-based nanostructures were lacking.

Purpose of the Study:

• To develop a general approach for synthesizing sub-nanometer platinum alloy nanowires (NWs).
• To investigate the ORR performance of these novel Pt-based NWs.
• To understand the underlying mechanisms for enhanced catalytic activity.

Main Methods:

• General synthesis of sub-nanometer Pt alloy NWs (Pt, PtNi, PtCo, PtNiCo) with 4-5 atomic layer thickness.
• Electrochemical characterization of ORR activity (mass and specific activity).
• Density Functional Theory (DFT) simulations to elucidate catalytic mechanisms.

Main Results:

• Achieved exceptional mass activity (4.20 A/mg) and specific activity (5.11 mA/cm²) at 0.9 V vs RHE.
• Activities were significantly higher (32.3x and 26.9x) than commercial Pt/C.
• Demonstrated excellent stability with negligible decay over 30,000 cycles.
• DFT revealed high-density (111) facets contribute to enhanced ORR activity.

Conclusions:

• Sub-nanometer Pt alloy NWs exhibit unprecedented ORR performance, defying trends seen in nanoparticles.
• The synthesis method allows for atomic-level utilization of Pt, maximizing catalytic efficiency.
• These findings open new avenues for designing highly active and stable electrocatalysts for heterogeneous catalysis.