Abécassis Benjamin, Greenberg Matthew W, Bal Vivekananda, McMurtry Brandon M, Campos Michael P, Guillemeney Lilian, Mahler Benoit, Prevost Sylvain, Sharpnack Lewis, Hendricks Mark P, DeRosha Daniel, Bennett Ellie, Saenz Natalie, Peters Baron, Owen Jonathan S
Laboratoire de Chimie, ENS de Lyon, CNRS, Université Claude Bernard Lyon 1 F69342 Lyon France.
Department of Chemistry, Columbia University New York New York 10027 USA
Chem Sci. 2022 Mar 30;13(17):4977-4983. doi: 10.1039/d1sc06134h. eCollection 2022 May 4.
Modern syntheses of colloidal nanocrystals yield extraordinarily narrow size distributions that are believed to result from a rapid "burst of nucleation" (La Mer, , 1950, (11), 4847-4854) followed by diffusion limited growth and size distribution focusing (Reiss, , 1951, , 482). Using a combination of X-ray scattering, optical absorption, and 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/) fits the data with a single growth rate constant ( ) across all three precursors. However, the magnitude of the 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.
现代胶体纳米晶体的合成产生了极其狭窄的尺寸分布，据信这是由快速的“成核爆发”（拉默，1950年，（11），4847 - 4854）导致的，随后是扩散限制生长和尺寸分布聚焦（赖斯，1951年，，482）。我们结合使用X射线散射、光吸收和碳核磁共振（NMR）光谱，监测了由三种硫脲前体生成PbS溶质、成核和晶体生长的动力学，这三种前体的转化反应活性跨越了2倍的范围。在所有三种情况下，都发现成核缓慢，并且在超过50%的沉淀过程中持续进行。基于尺寸依赖生长规律（1/）的群体平衡模型，用一个单一的生长速率常数（）拟合了所有三种前体的数据。然而，的大小以及对溶剂粘度缺乏依赖性表明，速率限制步骤不是从溶液扩散到纳米颗粒表面。我们提出了几种表面反应限制机制和一个配体渗透模型，该模型使用一个单一的拟合参数来拟合我们实验的数据，以解释这些结果。
