Intermetallic Nanoparticles: Synthetic Control and Their Enhanced Electrocatalysis

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Intermetallic nanoparticles (NPs) possess unique ordered structures with strong d-orbital interactions, offering superior stability against oxidation and etching compared to solid solution alloy NPs.
• Their well-defined atomic arrangements make them ideal model systems for fundamental studies of physical and catalytic properties.

Purpose of the Study:

• To summarize synthetic principles and strategies for producing monodisperse intermetallic NPs, with a focus on tetragonal L1₀-NPs.
• To discuss the thermodynamics and kinetics governing structural transitions in NPs.
• To highlight strategies for enhancing intermetallic structure formation and correlating NP structure with catalytic performance.

Main Methods:

• Two primary synthetic approaches are detailed: solution-phase synthesis followed by solid-state annealing, and direct solution-phase synthesis.
• Strategies to facilitate intermetallic formation include introducing vacancies/defects and controlling atom addition rate or seed-mediated diffusion.
• The d-band theory is employed to explain how electronic, strain, and ensemble effects tune catalytic properties.

Main Results:

• Demonstrated successful synthesis of monodisperse intermetallic NPs, particularly Pt-, Pd-, and Au-based L1₀-NPs.
• Showcased significantly enhanced catalytic activity for electrochemical reactions such as oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and formic acid oxidation reaction (FAOR).
• Elucidated the role of first-row transition metals in catalysis due to enhanced stability in the intermetallic structure.

Conclusions:

• Developed effective synthetic strategies for intermetallic NPs by controlling thermodynamics and kinetics.
• Intermetallic NPs exhibit superior catalytic performance for key electrochemical reactions, driven by their unique structural and electronic properties.
• The findings offer a pathway for optimizing NP catalysis for chemical and energy applications through rational design of intermetallic structures.