Two step continuous method to synthesize colloidal spheroid gold nanorods.

Area of Science:

• Nanotechnology
• Materials Science
• Colloidal Chemistry

Background:

• Gold nanoparticles exhibit unique optical properties.
• Controlling nanoparticle shape is crucial for tuning these properties.
• Continuous synthesis methods offer advantages in scalability and efficiency.

Purpose of the Study:

• To develop a continuous, two-step synthesis for spheroid gold nanorods.
• To investigate the influence of reactant ratios on nanoparticle morphology.
• To characterize the optical properties of the synthesized gold nanorods.

Main Methods:

• A two-step continuous synthesis involving gold precursor reduction and subsequent growth.
• Controlled addition of silver nitrate and ascorbic acid to manipulate shape.
• Characterization of nanoparticle size, shape, and optical properties.

Main Results:

• Spheroid gold nanorods with aspect ratios of ~1.85-2.2 were synthesized at specific ascorbic acid to silver nitrate weight ratios (1.35-1.75).
• Spherical nanoparticles were formed at lower weight ratios (0.5-1.1).
• An alkaline medium enhanced gold nanorod yield and reduced reaction time at room temperature.

Conclusions:

• The developed continuous process enables controlled synthesis of spheroid gold nanorods.
• Morphology control is achievable by adjusting the weight ratio of ascorbic acid to silver nitrate.
• Synthesized gold nanorods exhibit stable optical properties in ethanol, with a slight red shift in surface plasmon resonance.