Mozaffari Saeed, Li Wenhui, Thompson Coogan, Ivanov Sergei, Seifert Soenke, Lee Byeongdu, Kovarik Libor, Karim Ayman M
Department of Chemical Engineering, Virginia Polytechnic Institute and State University.
Center for Integrated Nanotechnologies, Los Alamos National Laboratory.
J Vis Exp. 2018 Jun 25(136):57667. doi: 10.3791/57667.
The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.
封端配体的存在对胶体纳米粒子的尺寸、尺寸分布和稳定性有很大影响。尽管封端配体在合成反应中起着关键作用，但其在调节胶体纳米粒子成核和生长速率方面的作用仍未得到充分理解。在这项工作中，我们使用原位小角X射线散射（SAXS）和基于配体的动力学模型，对三辛基膦（TOP）在不同溶剂（甲苯和吡啶）中的钯纳米粒子中的作用进行了机理研究。我们在不同合成条件下的结果揭示了反应过程中钯纳米粒子成核和生长的重叠，这与拉默型成核和生长模型相矛盾。该模型考虑了前驱体和颗粒表面钯-TOP结合的动力学，这对于原位捕获尺寸演变以及颗粒浓度至关重要。此外，我们通过设计合成条件以获得具有所需尺寸的纳米粒子，展示了基于配体模型的预测能力。所提出的方法可应用于其他合成系统，因此是胶体纳米粒子预测合成的有效策略。
