Small bimetallic (Pt/Pd) particles by biosynthesis: transmission electron microscopy and quantum mechanical analysis

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Bimetallic nanoparticles offer unique catalytic and electronic properties.
• Controlling nanoparticle size and structure is crucial for optimizing performance.
• Bio-reduction presents a sustainable synthesis route for nanomaterials.

Purpose of the Study:

• To synthesize bimetallic palladium/platinum (Pd/Pt) nanoparticles using a bio-reduction method.
• To characterize the structural, morphological, and elemental properties of the synthesized nanoparticles.
• To investigate the structural stability and electronic properties using molecular simulations.

Main Methods:

• Bio-reduction synthesis of Pd/Pt nanoparticles.
• High-resolution transmission electron microscopy (HRTEM) for structural analysis.
• Energy-dispersive spectroscopy (EDS) for elemental composition.
• Quantum mechanics-based molecular simulations for stability and electronic properties.

Main Results:

• Particle size and distribution were found to be pH-dependent.
• At pH 4, a bimodal size distribution with an average of 3.2 nm was observed.
• At pH 7, the average particle size increased to 3.9 nm with higher variance.
• HRTEM revealed fcc-like clusters, potentially pure Pd, pure Pt, or bimetallic Pd/Pt.
• Molecular simulations identified a Pd18Pt37 eutectic-like structure as the most stable configuration, suggesting a cluster-in-cluster form.

Conclusions:

• The bio-reduction method is effective for synthesizing bimetallic Pd/Pt nanoparticles.
• pH significantly influences nanoparticle size and distribution.
• The Pd18Pt37 cluster-in-cluster structure represents a highly stable configuration for these bimetallic nanoparticles.