Quantitative In Situ Visualization of Thermal Effects on the Formation of Gold Nanocrystals in Solution,Advanced Materials

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Quantitative In Situ Visualization of Thermal Effects on the Formation of Gold Nanocrystals in Solution
Advanced Materials ( IF 27.4 ) Pub Date : 2021-08-02 , DOI: 10.1002/adma.202102514
Abdelali Khelfa ₁ , Jaysen Nelayah ₁ , Hakim Amara _{1,

2} , Guillaume Wang ₁ , Christian Ricolleau ₁ , Damien Alloyeau ₁

Affiliation

Understanding temperature effects in nanochemistry requires real-time in situ measurements because this key parameter of wet-chemical synthesis simultaneously influences the kinetics of chemical reactions and the thermodynamic equilibrium of nanomaterials in solution. Here, temperature-controlled liquid cell transmission electron microscopy is exploited to directly image the radiolysis-driven formation of gold nanoparticles between 25 °C and 85 °C and provide a deeper understanding of the atomic-scale processes determining the size and shape of gold colloids. By quantitatively comparing the nucleation and growth rates of colloidal assemblies with classical models for nanocrystal formation, it is shown that the increase of the molecular diffusion and the solubility of gold governs the drastic changes in the formation dynamics of nanostructures in solution with temperature. In contraction with the common view of coarsening processes in solution, it is also demonstrated that the dissolution of nanoparticles and thus the Ostwald ripening is not only driven by size effects. Furthermore, visualizing thermal effects on faceting processes at the single nanoparticle level reveals how the competition between the growth speed and the surface diffusion dictates the final shape of nanocrystals.

中文翻译：

热效应对溶液中金纳米晶体形成的定量原位可视化

了解纳米化学中的温度效应需要实时原位测量，因为湿化学合成的这一关键参数同时影响化学反应动力学和纳米材料在溶液中的热力学平衡。在这里，温度控制的液体细胞透射电子显微镜被用来直接成像在 25 ° C 和 85 °之间的金纳米粒子的辐射驱动形成C 并提供对决定金胶体大小和形状的原子级过程的更深入了解。通过将胶体组装体的成核和生长速率与纳米晶体形成的经典模型进行定量比较，表明分子扩散和金溶解度的增加控制了溶液中纳米结构的形成动力学随温度的剧烈变化。在溶液中粗化过程的普遍观点中，还证明纳米粒子的溶解和奥斯特瓦尔德熟化不仅受尺寸效应的驱动。此外，在单个纳米颗粒水平上对刻面过程的热效应可视化揭示了生长速度和表面扩散之间的竞争如何决定纳米晶体的最终形状。

更新日期：2021-09-21

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