SERS Activity in Gold Particles Obtained via a Modified Seeded-Growth Method.

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Optimizing plasmonic performance requires precise control over nanoparticle morphology and spatial arrangement.
• Gold nanoparticles (AuNPs) are crucial for applications like Surface-Enhanced Raman Scattering (SERS).

Purpose of the Study:

• To investigate the role of the HAuCl4/NaBH4 molar ratio in gold nanoparticle synthesis.
• To understand how this ratio influences formation kinetics, structure, and SERS response.
• To explore the potential for bottom-up strategies in tuning plasmonic properties.

Main Methods:

• Seed-mediated synthesis of gold nanoparticles (AuNPs).
• Real-time ultraviolet-visible (UV-Vis) spectroscopy to monitor kinetics.
• Electron microscopy (SEM and TEM) for structural analysis.
• SERS measurements to evaluate plasmonic response.

Main Results:

• The HAuCl4/NaBH4 ratio dictates distinct kinetic regimes (diffusion-limited vs. chemically controlled growth).
• Equimolar (1:1) ratio yields larger triangular nanoplates with enhanced plasmonic coupling.
• SERS intensity increased up to 9-fold with the equimolar ratio compared to other ratios.

Conclusions:

• Kinetic regulation via precursor ratio is an effective strategy for directing anisotropic growth of AuNPs.
• This method allows tuning of plasmonic properties without post-synthetic modification.
• The findings enable the development of highly sensitive SERS substrates for molecular detection and plasmonic sensing.