爱因斯坦茶叶悖论引发了纳米颗粒的局部聚集及其向金气凝胶的转变。
Einstein's tea leaf paradox induced localized aggregation of nanoparticles and their conversion to gold aerogels.
作者信息
Zhang Zehui, Zhou Bin, Jia Mingtao, Wu Chengbin, Niu Tingting, Feng Chen, Wang Hongqiang, Liu Yanfeng, Lu Jialu, Zhang Zhihua, Shen Jun, Du Ai
机构信息
Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.
School of Resources and Safety Engineering, Central South University, Changsha, Hunan 410012, China.
出版信息
Sci Adv. 2023 Sep 15;9(37):eadi9108. doi: 10.1126/sciadv.adi9108.
Normally, stirring is regarded as a technology to disperse the substances in liquid evenly. However, Einstein's tea leaf paradox (ETLP) describes the phenomenon that tea leaves concentrate in a "doughnut" shape via a secondary flow effect while stirring. Herein, to demonstrate ETLP-induced concentration in nanofluid, we simulated the nanoparticle trajectory under stirring and made a grayscale analysis of SiO nanofluids during stirring and standing processes. Unexpectedly, a localized concentration effect in the layer flow was found beside the macroscopic ETLP effect. Subsequently, the localized concentration was applied to achieve the ultrafast aggregation of Au nanoparticles to form gold aerogels (GAs). The skeleton size of GAs was adjusted from about 10 to 200 nm by only adjusting the temperature of HAuCl solution. The fabricated GAs had extremely high purity and crystallinity, revealing potential applications in photocatalysis and surface-enhanced Raman scattering.
通常，搅拌被视为一种使物质在液体中均匀分散的技术。然而，爱因斯坦茶叶悖论（ETLP）描述了在搅拌过程中茶叶通过二次流效应集中成“甜甜圈”形状的现象。在此，为了证明纳米流体中由ETLP引起的聚集，我们模拟了搅拌下纳米颗粒的轨迹，并对SiO纳米流体在搅拌和静置过程中进行了灰度分析。出乎意料的是，在宏观ETLP效应之外，还发现了层流中的局部聚集效应。随后，利用这种局部聚集实现了金纳米颗粒的超快聚集，形成了金气凝胶（GAs）。仅通过调节HAuCl溶液的温度，就可以将GAs的骨架尺寸从约10纳米调整到200纳米。制备的GAs具有极高的纯度和结晶度，在光催化和表面增强拉曼散射方面显示出潜在的应用价值。
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