Missing Piece of the Mechanism of the Turkevich Method: The Critical Role of Citrate Protonation

Kettemann, Frieder; Birnbaum, Alexander; Witte, Steffen; Wuithschick, Maria; Pinna, Nicola; Kraehnert, Ralph; Rademann, Klaus; Polte, Jörg

doi:10.1021/acs.chemmater.6b01796

Cited by 62 publications

(83 citation statements)

References 30 publications

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“…Citrate ions are widely utilized in the wet chemical synthesis of silver [3][4][5][6][7][8][9][10][11][12][13][14], gold [15][16][17][18][19][20][21], platinum [22] and other nanoparticles, acting as reducing (direct reduction of aqueous Ag + ions by citrate occurs under boiling or hydrothermal conditions [9][10][11][12][13]), complexing, and stabilizing agent, although the precise mechanisms are far from being fully understood. Сitrate is a key reagent for the preparation of silver nanoplates, cubes, disks, etc., as the selective adsorption of citrate on Ag (111) facets impedes their growth and promotes the yield of anisotropic particles [12,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Mikhlin

Vorobyev

Сайкова

et al. 2018

Applied Surface Science

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Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles 3 immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag + ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

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Section: Introductionmentioning

confidence: 99%

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Mikhlin

Vorobyev

Сайкова

et al. 2018

Applied Surface Science

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“…After the work by Kumar et al [7], authors such as Ji et al [8], Polte et al [9], and Kettemann et al [10] NPs evolve according to the nucleation-aggregation-growth mechanism described, for instance, by Polte et al [9]. These findings prompted us to investigate the model of Kumar et al [7] for different conditions (including different pH values) and verify whether its predictions are accurate or not.…”

Section: Introductionmentioning

confidence: 89%

“…Recent experimental data [10], [13] indicate that the precursor takes two paths: the reduction to form the nuclei and the passivation by . After nucleation, the nuclei aggregate to bigger sizes forming seeds.…”

Section: B Final Ph Of the Mixturementioning

confidence: 99%

A mathematical investigation of the Turkevich organizer theory in the citrate method for the synthesis of gold nanoparticles

Agunloye

Gavriilidis

Mazzei

2017

Chemical Engineering Science

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Abstract-Gold nanoparticles are commonly synthesized by reducing chloroauric acid with sodium citrate. This method, referred to as the citrate method, can produce spherical gold nanoparticles (NPs) in the size range 10-150 nm. Gold NPs of this size are useful in many applications. However, the NPs are usually polydisperse and irreproducible. A better understanding of the synthesis mechanisms is thus required. This work thoroughly investigated the only model that describes the synthesis. This model combines mass and population balance equations, describing the NPs synthesis through a sequence of chemical reactions. Chloroauric acid reacts with sodium citrate to form aurous chloride and dicarboxy acetone. The latter organizes aurous chloride in a nucleation step and concurrently degrades into acetone. The unconsumed precursor then grows the formed nuclei. However, depending on the pH, both the precursor and the reducing agent react differently thus affecting the synthesis. In this work, we investigated the model for different conditions of pH, temperature and initial reactant concentrations. To solve the model, we used Parsival, a commercial numerical code, whilst to test it, we considered various conditions studied experimentally by different researchers, for which results are available in the literature. The model poorly predicted the experimental data. We believe that this is because the model does not account for the acid-base properties of both chloroauric acid and sodium citrate.

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“…demonstrated that there is an optimal pH value that gives rise to uniform and monodisperse AuNP. In the same sense, Kettermann et al . studied the Turkevich method in great detail alerting about the influence of the resulting pH of the solution on the size and polydispersion of the obtained AuNP.…”

Section: Introductionmentioning

confidence: 99%

Mild Homogeneous Synthesis of Gold Nanoparticles through the Epoxide Route: Kinetics, Mechanisms, and Related One‐Pot Composites

Oestreicher

Huck‐Iriart

Soler-Illia

et al. 2020

Chemistry A European J

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A new one‐pot homogeneous methodology at room temperature to obtain Au nanoparticles (AuNP) on the basis of the epoxide route is presented. The proposed method takes advantage of the homogenous generation of OH− moieties driven by epoxide ring‐opening, mediated by chloride nucleophilic attack. Once reached alkaline conditions, the reducing medium allows the quantitative formation of AuNP under well‐defined kinetic control. A stabilizing agent, such as polyvinylpyrrolidone (PVP) or cetyltrimethylammonium chloride (CTAC), is required to maintain the AuNP stable. Meanwhile their presence dramatically affects the reduction kinetics and pathway, as demonstrated by the evolution of the UV/Vis spectra, small‐angle X‐ray scattering (SAXS) patterns, and pH value along the reaction. In the presence of PVP nanogold spheroids are obtained following a similar reduction mechanism as that observed for control experiments in the absence of PVP. However, if CTAC is employed a stable complex with AuIII is formed, leading to a different reaction pathway and resulting in ellipsoidal‐like shaped AuNP. Moreover, the proposed methodology allows stabilize the growing AuNP, by coupling their formation with nonalkoxidic sol–gel reactions, leading to nanocomposite gels with embedded metallic nanoparticles. The epoxide route thus offers a versatile scenario for the one‐pot preparation of new metal nanoparticles–inorganic/hybrid matrices nanocomposites with valuable optical properties.

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Missing Piece of the Mechanism of the Turkevich Method: The Critical Role of Citrate Protonation

Cited by 62 publications

References 30 publications

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

A mathematical investigation of the Turkevich organizer theory in the citrate method for the synthesis of gold nanoparticles

Mild Homogeneous Synthesis of Gold Nanoparticles through the Epoxide Route: Kinetics, Mechanisms, and Related One‐Pot Composites

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