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Persistent nucleation and size dependent attachment kinetics produce monodisperse PbS nanocrystals
Modern syntheses of colloidal nanocrystals yield extraordinarily narrow size distributions that are believed to result from a rapid "burst of nucleation" (La Mer, JACS , 1950, 72 (11), 4847-4854) followed by diffusion limited growth and size distribution focusing (Reiss, J. Chem. Phys. , 1...
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Published in: | Chemical science (Cambridge) 2022-05, Vol.13 (17), p.4977-4983 |
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Main Authors: | , , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Modern syntheses of colloidal nanocrystals yield extraordinarily narrow size distributions that are believed to result from a rapid "burst of nucleation" (La Mer,
JACS
, 1950,
72
(11), 4847-4854) followed by diffusion limited growth and size distribution focusing (Reiss,
J. Chem. Phys.
, 1951,
19
, 482). Using a combination of
in situ
X-ray scattering, optical absorption, and
13
C nuclear magnetic resonance (NMR) spectroscopy, we monitor the kinetics of PbS solute generation, nucleation, and crystal growth from three thiourea precursors whose conversion reactivity spans a 2-fold range. In all three cases, nucleation is found to be slow and continues during >50% of the precipitation. A population balance model based on a size dependent growth law (1/
r
) fits the data with a single growth rate constant (
k
G
) across all three precursors. However, the magnitude of the
k
G
and the lack of solvent viscosity dependence indicates that the rate limiting step is not diffusion from solution to the nanoparticle surface. Several surface reaction limited mechanisms and a ligand penetration model that fits data our experiments using a single fit parameter are proposed to explain the results.
In situ
X-ray scattering kinetics and population balance modeling of crystal nucleation and growth. |
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ISSN: | 2041-6520 2041-6539 |
DOI: | 10.1039/d1sc06134h |