In Situ Liquid Cell TEM Reveals Bridge-Induced Contact and Fusion of Au Nanocrystals in Aqueous Solution
In Situ Liquid Cell TEM Reveals Bridge-Induced Contact and Fusion of Au Nanocrystals in Aqueous Solution
复制标题
DOI：
10.1021/acs.nanolett.8b03139
复制
发表时间：
2018-10-01
期刊：
影响因子：
10.8
通讯作者：
Tang, Ruikang
中科院分区：
文献类型：
--
作者：
Jin, Biao;Sushko, Maria L.;Tang, Ruikang
在纳米粒子在水溶液中的聚结过程中，粒子的脱水和初始接触是非常重要但知之甚少的过程。在这项工作中，我们使用原位液池透射电子显微镜直接可视化的聚结过程的Au纳米晶体。结果表明，Au原子纳米桥形成于相邻纳米晶之间，相邻纳米晶之间被一层约0.5 nm的水化层隔开。纳米桥结构首先诱导Au纳米晶体在其水化层上的初始接触，然后表面扩散和晶界迁移以重新排列成单个纳米晶体。经典的密度泛函理论计算和从头算分子动力学模拟表明，纳米桥的形成是由于金离子在差距中的积累和较高的局部过饱和度，从而促进了Au纳米晶的脱水、接触和融合.这一多步骤过程的发现推进了我们对水溶液中纳米颗粒聚结机制的理解。
During nanoparticle coalescence in aqueous solution, dehydration and initial contact of particles are critically important but poorly understood processes. In this work, we used in situ liquid-cell transmission electron microscopy to directly visualize the coalescence process of Au nanocrystals. It is found that the Au atomic nanobridge forms between adjacent nanocrystals that are separated by a similar to 0.5 nm hydration layer. The nanobridge structure first induces initial contact of Au nanocrystals over their hydration layers and then surface diffusion and grain boundary migration to rearrange into a single nanocrystal. Classical density functional theory calculations and ab initio molecular dynamics simulations suggest that the formation of the nanobridge can be attributed to the accumulation of auric ions and a higher local supersaturation in the gap, which can promote dehydration, contact, and fusion of Au nanocrystals. The discovery of this multistep process advances our understanding of the nanoparticle coalescence mechanism in aqueous solutions.