Eco-friendly Synthesis of Silver Nanoparticles using Ascorbic Acid and its Optical Characterization

The noble metallic nanoparticles, such as silver and gold nanoparticles, are of great interest in the field of nanotechnology, sensing, medical diagnostics, and therapeutic applications. The wide range of applications is largely due to the distinct physical, chemical, biological, and optical properties exhibited by these nanoparticles. Notably, their optical behavior is demonstrated by the Laser Surface Plasmon Resonance (LSPR) phenomena, which can be characterized through UV-Vis spectrophotometry.

In this study, silver nanoparticles are synthesized using a non-toxic and eco-friendly method. The Vitamin C (Ascorbic Acid) acts as a chemical reductant to successfully reduce silver ions into silver nanoparticles. During this process, several sets of reaction mixtures were prepared considering factors such as the pH of the mixture, requirement of heat, and the appropriate amount of supporting reagents needed for proper size control. With a little agitation, the progression of the reaction becomes evident through visual changes in just a couple of minutes. A beautiful array of colorful nanoparticle solutions is produced, each of which exhibits the LSPR phenomenon. The optimized synthetic method utilizes higher pH conditions, sodium citrate as a silver ion stabilizer, hydrogen peroxide as an etching agent, and ascorbic acid as a reducing agent, allowing nanoscale-sized silver particles to be achieved even at the room temperature. The LSPR absorption band was found around 400 nm via UV-Vis spectrophotometry. The relationship between the color of the solution, the plasmon absorption band, and thereby the size and shape of the nanoparticles will be discussed.