Experimental and theoretical study of the mechanism formation of silver nanoclusters in the reduction reaction of Ag+ ions by alizarin solution

Abstract

For the study of the processes of the Ag+ ions interaction with humic substances a low molecular weight model compound – alizarin – was used for the first time in the present work. It has been established that alizarin carries out a double role in the process of synthesis of silver nanoparticles: reducing agent of Ag+ ions and a stabilizer of the formed nanoparticles. Based on the analysis of experimental data a mechanism of silver nanoparticles formation was proposed. In particular, at the moment of mixing of the reagents, a microphase Ag2O is formed and becomes a source of silver ions in solution. Alizarin molecules form a complex with silver ions, which provide the centres of primary clusters formation. The growth of primary clusters occurs through the reduction of Ag+ ions from the solution. Organic component of the complex undergoes oxidative hydroxylation by the Elbs reaction type.