Tracking of photochemical Ostwald ripening of nanoparticles through voltammetric atom counting

Bartlett, Thomas R.; Sokolov, Stanislav V.; Plowman, Blake J.; Young, Neil P.; Compton, Richard G.

doi:10.1039/c6nr05740c

Cited by 12 publications

(19 citation statements)

References 25 publications

(43 reference statements)

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“…Following this, the UV−vis spectra of the citrate−AgNPs are reported with the addition of different concentrations of lead(II) solutions (UV− vis Responses of the Citrate−AgNP/Pb2+ Solutions). In order h: 33 ± 9, c l: 7 ± 1 19 25 ± 15 344 ± 1 13 980 ± 190…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The spherical citrate–AgNPs of 9 nm diameter and the triangular prismatic citrate–AgNPs were synthesized in our research group. − The spherical citrate–AgNPs of 30, 50, and 100 nm diameters were obtained from Nanocomposix, U.S.A. All of the citrate–AgNPs were characterized using transmission electron microscopy (TEM, 300 kV JEOL 3000F microscope) and dynamic light scattering (DLS, ZEN3600 Nano-ZS Zetasizer).…”

Section: Methodsmentioning

confidence: 99%

“…The value of ε ext per silver nanoparticle can also be approximated, see S2 (SI). 19 † h and l are the height of the triangular surface and the thickness of the prism respectively.…”

Section: Uv-vis Studies Of Citrate-agnps and The Interpretation Of Thmentioning

confidence: 99%

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Dynamics of Silver Nanoparticles in Aqueous Solution in the Presence of Metal Ions

et al. 2017

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Using a combined UV-vis, DLS, and electrochemical approach, this work experimentally studies the physical origin of the observed colorimetric sensitivity of aqueous silver nanoparticles toward divalent metal ions. In the presence of Pb, AgNPs are slow to reversibly form agglomerates (the time scale of the reverse deagglomeration process is of the order of hours). This agglomeration is shown to be induced by complex formation between Pb and citrate groups localized on the AgNPs, reducing surface charges (zeta-potential) and hence electrostatic repulsion between the AgNPs. Other divalent metal ions including Ca, Cd, Zn, Ni, Co, and Sn are also studied, and the resulting sizes of the AgNPs clusters and the extents of the UV-vis spectrum red-shift in λ have a strong positive correlation with the metal-ligand (citrate) complex formation constant (K). This work thus serves as a guide for the selection of capping agents on the basis of K and demonstrates the correlation between sizes and spectrophotometric as well as electrochemical responses of the AgNPs clusters. Importantly, we give further physical insights into the size-dependent properties of AgNPs and emphasize the difference between theoretical and experimental values of extinction coefficients, where the latter is affected by the angle-dependent scattering intensities and the measurement technique used.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Dynamics of Silver Nanoparticles in Aqueous Solution in the Presence of Metal Ions

et al. 2017

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“…In the nano-impact measurements, the total charge transferred during each current-transient spike directly relates to the number of constituent electroactive atoms or molecules of the nanoparticles, irrespective of their shape [19] or the presence of capping agents. [8] This is different from other techniques that measure the length scale of the particles such as transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

Single Oxidative Collision Events of Silver Nanoparticles: Understanding the Rate‐Determining Chemistry

Ngamchuea

Clark

Sokolov

et al. 2017

Chemistry A European J

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The oxidative dissolution of citrate-capped silver nanoparticles (AgNPs, ∼50 nm diameter) is investigated herein by two electrochemical techniques: nano-impacts and anodic stripping voltammetry. Nano-impacts or single nanoparticle-electrode collisions allow the detection of individual nanoparticles. The technique offers an advantage over surface-immobilized methods such as anodic stripping voltammetry as it eliminates the effects of particle agglomeration/aggregation. The electrochemical studies are performed in different electrolytes (KNO , KCl, KBr and KI) at varied concentrations (≤20 mm). In nano-impact measurements, the AgNP undergoes complete oxidation upon impact at a suitably potentiostated electrode. The frequency of the nanoparticle-electrode collisions observed as current-transient spikes depends on the electrolyte identity, its concentration and the potential applied at the working electrode. The frequencies of the spikes are significantly higher in the presence of halide ions and increase with increasing potentials. From the frequency, the rate of AgNP oxidation as compared with the timescale the AgNP is in electrical contact with the electrode can be inferred, and hence is indicative of the relative kinetics of the oxidation process. Primarily based on these results, we propose the initial formation of the silver (I) nucleus (Ag , AgCl, AgBr or AgI) as the rate-determining process of silver oxidation on the nanoparticle.

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“…Typically, a coalescence of particles or an Ostwald ripening occurs after nucleation of particles, 15,16 whereas in the present study particle growth stopped at a very early stage. The reason for this is unclear, but we speculate that these newly formed smaller nanoparticles are energetically preferred, since GSH seems to efficiently stabilise silver nanoparticles of this selected size.…”

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confidence: 64%

Kinetic monitoring of glutathione-induced silver nanoparticle disintegration

2018

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We report on etching of polyacrylic acid-stabilised silver nanoparticles in the presence of glutathione (GSH). The initial particles with a radius of 3.2 nm and consisting of ∼8100 silver atoms dissolve in a twostep reaction mechanism while in parallel smaller silver particles with a radius of 0.65 nm and consisting of 60 to 70 silver atoms were formed. The kinetics of the etching of the initial particles, accompanied by formation of smaller silver particles was interpreted based on in situ, time-resolved small-angle X-ray scattering (SAXS) experiments.

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Tracking of photochemical Ostwald ripening of nanoparticles through voltammetric atom counting

Cited by 12 publications

References 25 publications

Dynamics of Silver Nanoparticles in Aqueous Solution in the Presence of Metal Ions

Dynamics of Silver Nanoparticles in Aqueous Solution in the Presence of Metal Ions

Single Oxidative Collision Events of Silver Nanoparticles: Understanding the Rate‐Determining Chemistry

Kinetic monitoring of glutathione-induced silver nanoparticle disintegration

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