Okeil Sherif, Rabet Sahar, Valadez Huerta Gerardo, Raabe Gabriele, Garnweitner Georg
Institute for Particle Technology, Technische Universität Braunschweig, Volkmaroder Str. 5, 38104 Braunschweig, Germany.
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Ain Shams University, Abbassia, Cairo 11566, Egypt.
Langmuir. 2024 Sep 17;40(37):19343-19356. doi: 10.1021/acs.langmuir.4c00921. Epub 2024 Sep 3.
The controlled synthesis of nanoparticles with tailored shapes and morphologies has garnered significant attention, driven by the ever-growing demand for advanced materials with defined properties. In nanoparticle formation, various parameters influence the final product, and among these, the solvent plays a pivotal role, as it constitutes the major component of the reaction medium. In this work, the critical role of solvents in controlling the growth of zinc oxide (ZnO) nanoparticles was investigated, with a focus on simple primary alcoholic solvents as the reaction medium. A model reaction based on the direct solvolysis of anhydrous zinc acetylacetonate was employed to probe the influence of different primary alcohols, specifically methanol, ethanol, and their mixture. A substantial difference in the preferential growth direction of the ZnO nanocrystals in methanol and ethanol was observed through XRD and was further proven through TEM. Thereby, in ethanol, a preferential growth in the [001] direction was observed, resulting in short nanorods as primary particles, while this growth was inhibited in methanol, leading to platelet- or sheet-like primary particles. To unravel the underlying mechanisms responsible for the observed solvent-dependent variations, molecular dynamics (MD) simulations were employed using an optimized interface force field to model the ZnO-alcohol interaction. These simulations provide valuable insights into the preferential adsorption of the solvent molecules onto the polar (0001) and (0001̅) and nonpolar (101̅0) ZnO surfaces, shedding light on the fundamental interactions driving the shape control phenomenon. Essentially, the experimental observations on primary particle morphology could be explained well by the adsorption behavior determined by the MD simulations. Furthermore, this report provides an extensive comparison with various similar reaction systems for ZnO synthesis, deriving correlations with the findings from the model system. These insights contribute to a deeper understanding of the intricate interplay between solvent properties and nanoparticle growth, offering a valuable toolkit for designing and optimizing the synthesis of ZnO nanoparticles with specific shapes and functionalities.
随着对具有特定性能的先进材料的需求不断增长，具有定制形状和形态的纳米颗粒的可控合成受到了广泛关注。在纳米颗粒的形成过程中，各种参数会影响最终产物，其中溶剂起着关键作用，因为它是反应介质的主要成分。在这项工作中，研究了溶剂在控制氧化锌（ZnO）纳米颗粒生长中的关键作用，重点是使用简单的伯醇类溶剂作为反应介质。采用基于无水乙酰丙酮锌直接溶剂分解的模型反应来探究不同伯醇（特别是甲醇、乙醇及其混合物）的影响。通过X射线衍射（XRD）观察到甲醇和乙醇中ZnO纳米晶体的择优生长方向存在显著差异，并通过透射电子显微镜（TEM）进一步证实。因此，在乙醇中，观察到沿[001]方向的择优生长，形成短纳米棒作为初级颗粒，而在甲醇中这种生长受到抑制，导致形成片状或薄片状初级颗粒。为了揭示导致观察到的溶剂依赖性变化的潜在机制，使用优化的界面力场进行分子动力学（MD）模拟，以模拟ZnO-醇的相互作用。这些模拟为溶剂分子在极性（0001）和（0001̅）以及非极性（101̅0）ZnO表面的择优吸附提供了有价值的见解，揭示了驱动形状控制现象的基本相互作用。从本质上讲，MD模拟确定的吸附行为可以很好地解释初级颗粒形态的实验观察结果。此外，本报告与各种类似的ZnO合成反应体系进行了广泛比较，得出了与模型体系研究结果的相关性。这些见解有助于更深入地理解溶剂性质与纳米颗粒生长之间的复杂相互作用，为设计和优化具有特定形状和功能的ZnO纳米颗粒的合成提供了宝贵的工具。
