Nucleation Control of Size and Dispersity in Aggregative Nanoparticle Growth. A Study of the Coarsening Kinetics of Thiolate-Capped Gold Nanocrystals

Abstract

The thermal coarsening (180 °C) of decanethiolate-capped Au nanocrystals is studied at various tetraoctylammonium bromide concentrations. The coarsening kinetics are determined by measuring nanocrystal size distributions (CSDs) as a function of time. The results are shown to be consistent with aggregative nucleation and growth. For each kinetic trial, the time dependence of the aggregative nucleation rate is extracted from the early time CSDs and fitted by a Gaussian profile. The height of the profile is the maximum nucleation rate, Γmax, and the 2σ width is the time window for nucleation, Δt n. These nucleation parameters are shown to control the final mean size and size distribution of the coarsened nanocrystals. The coarsening kinetics are influenced by tetraoctylammonium bromide concentration because the nanocrystals are partially electrostatically stabilized.

pH-induced aggregation growth of large Au nanoparticles from zwitterionic ligand-modified small Au nanoparticles

“…Moreover, their growth kinetics shows typical sigmoidal-type curve. That is, an initial induction period was followed by a process of rapid growth, and after that the further growth was discontinued for a long time, which is consistent with the growth kinetics associated with the OA growth [19,30]. Therefore, the acidification-mediated particle growth observed in this study may proceed via the OA mechanism as well, as can be directly revealed by looking the morphology of the intermediate products.…”

“…Goubet et al found that thermal treatment leads to small Au seeds stuck together and completely melted, forming large particles [18]. Shields et al systematically studied the thermal coarsening kinetics of thiolate-capped Au NPs in the presence of tetraoctylammonium bromide [19]. They found that the growth kinetics shows a typical sigmoidal curve, which is against the OR growth.…”

Elucidating Strong Field Photochemical Reduction Mechanisms of Aqueous [AuCl4]−: Kinetics of Multiphoton Photolysis and Radical-Mediated Reduction

“…9,10 Ever since LaMer's development of classical nucleation theory in 1950, 11 this nucleation− growth model has commonly been used to describe the kinetics of AuNP formation up to the present day. 9,12,13 However, as early as Turkevich's 1951 study of HAuCl 4 reduction by sodium citrate, 14 alternative AuNP formation mechanisms including autocatalysis 14−16 and aggregative growth 17,18 have proven to better account for the observed kinetics of Au precursor reduction and AuNP growth. In particular, the quantitative Finke−Watsky rate law describing the autocatalytic nucleation and growth of Ir nanoclusters, 19 along with subsequent modifications to account for particle aggregation, 20 has recently been applied to HAuCl 4 reduction and AuNP growth under a variety of reaction conditions.…”

Kinetics of reaction of gold nanoparticles following partial removal of stabilizers

“…On the other hand, there has been extensive interest in the formation and growth kinetics of NPs from clusters involving two mechanisms-the Ostwald ripening and oriented attachment process (Ribeiro et al 2005, Shields et al 2010. It can be said that progress in the understanding of kinetics of aggregation of chemically synthesized colloidal NPs has been somewhat hindered by the lack of availability of sufficiently stable, bare and reactive NPs.…”