Formation of gold nanoparticles during the reduction of HAuBr sub(4) in reverse micelles of oxyethylated surfactant: Influence of gold precursor on the growth kinetics and properties of the particles

• Published in: Journal of materials research 2015-06, Vol.30 (12), p.1925-1933
• Main Authors: Sergievskaya, Anastasiya P, Tatarchuk, Vladimir V, Makotchenko, Evgeniya V, Mironov, Igor V
• Format: Article
• Language: English
• Subjects: Droplets; Gold; Nanoparticles; Nucleation; Precursors; Reduction; Reverse micelles; Surfactants
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2015.121

The growth kinetics of gold nanoparticles (NPs) during the reduction of HAuBr sub(4) by hydrazine in the reverse micelles of oxyethylated surfactant Tergitol NP 4 was studied in situ by UV-vis spectroscopy. Kinetic mechanism includes the steps of slow, continuous nucleation and fast, autocatalytic surface growth. Both steps are under kinetic control of the precursor reduction. The rate of nucleation is limited by reaction in the droplets of the aqueous phase forming the cores of reverse micelles, and growth rate is limited by the reaction on the surface of gold NPs growing inside the micelles. The chemical mechanism of reduction of halogenated forms of gold AuX sub(4) super(-) by hydrazine is the same in the case of X = Cl, Br and includes the equilibria of formation and redox decomposition of the intermediate complexes Au super(III)(N sub(2)H sub(4))X sub(3) and Au super(I)(N sub(2)H sub(4))X. The initial form of AuX sub(4) super(-) (X = Cl, Br) does not affect the size of the final NPs synthesized in micellar solution of oxyethylated surfactant.