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A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions
Published on: February 5, 2016
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A Facile pH Controlled Citrate-Based Reduction Method for Gold Nanoparticle Synthesis at Room Temperature
Himanshu Tyagi1, Ajay Kushwaha1, Anshuman Kumar1
1Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Nanoscale Research Letters
|August 16, 2016
Summary
This study revisits gold nanoparticle synthesis using a simplified room temperature method. Optimal pH 5 yields monodisperse gold nanoparticles with narrow size distribution, demonstrating enhanced stability and predictable outcomes via a theoretical model.
Area of Science:
- Nanotechnology
- Materials Science
- Physical Chemistry
Background:
- The synthesis of gold nanoparticles (AuNPs) is crucial for various applications.
- The standard Turkevich synthesis is a common method, but room temperature modifications are explored for efficiency.
- Controlling nanoparticle size and distribution remains a key challenge.
Purpose of the Study:
- To revisit and simplify the citrate reduction process for gold nanoparticle synthesis at room temperature.
- To investigate the influence of initial pH and reactant concentration on AuNP size and monodispersity.
- To develop and validate a theoretical model predicting AuNP size based on reaction kinetics and processes.
Main Methods:
- Simplified room temperature citrate reduction (Turkevich method).
- UV-vis spectroscopy and transmission electron microscopy (TEM) for characterization.
- Absorption spectroscopy for stability testing.
- Kinetic studies (UV absorbance) and theoretical modeling (population balance equation).
Main Results:
- Optimal pH 5 yielded highly monodisperse, spherical AuNPs with sharp surface plasmon resonance at 520 nm.
- Non-uniform pH conditions led to polydispersity and aggregation, indicated by red-shifted plasmon peaks.
- Room temperature synthesis produced stable colloidal suspensions with no aggregation observed for one month.
- Theoretical model predictions for particle size (13-25 nm) closely matched experimental results (10-32 nm).
Conclusions:
- A simplified room temperature approach enables controlled synthesis of monodisperse gold nanoparticles.
- Initial pH is a critical factor for achieving desired particle size and narrow distribution.
- The developed theoretical model accurately predicts AuNP size, validating the reaction kinetics and processes involved.
