SYNTHESIS AND CHARACTERIZATION OF SILVER NANOPARTICLES

Abstract

Silver nanoparticles have been formed with two different methods: by reduction of Ag+ ions from AgNO3 aqueous solution and reduction of Ag+ ions obtained by electrolysis in a pure water by using ultrapure Ag electrode. Glutathione and ascorbic acid have been used as reductive redox agents. The preparation has been conducted by mixing aqueous solutions of reactants at different concentrations. Formation of colloidal solutions containing silver nanoparticles has been confirmed by electrochemical, spectroscopic, and microscopic techniques. By applying UV-Vis spectroscopy the formation of nanoparticles has been supported with the localized surface plasmon resonance absorption peak at 350 nm. The morphology and dimensions of the formed silver nanoparticles have been studied by inspecting microphotographs collected by atomic force microscopy. The decrease of the concentration of the free Ag+ ions following the reduction with the reductants has been measured by anodic stripping voltammetry using square-wave voltammetry as a potential modulation form. As a result of addition of reductive agents, a colloid of silver nanoparticles is formed, which is not prone to detection with anodic stripping voltammetry. The problem was circumvented by using an excess of glutathione, causing adsorptive accumulation of silver nanoparticles at the electrode surface, thus enabling anodic oxidation and voltammetric detection of silver particles.