In Situ Study of Molecular Structure of Water and Ice Entrapped in Graphene Nanovessels
In Situ Study of Molecular Structure of Water and Ice Entrapped in Graphene Nanovessels
复制标题
DOI：
10.1021/acsnano.9b00914
复制
发表时间：
2019-04-01
期刊：
影响因子：
17.1
通讯作者：
Megaridis, Constantine M.
中科院分区：
文献类型：
--
作者：
Ghodsi, Seyed Mohammadreza;Anand, Sushant;Megaridis, Constantine M.
水在自然系统中无处不在，从浩瀚的海洋到地壳中的纳米毛细血管或细胞器。在体积或与固体表面密切接触时，水分子根据它们的氢(H)键排列自己，这对它们的短期和长期分子结构有重要影响。水分子间氢键的形成表示水的某些非键分子轨道的能级，这可以用光谱技术来量化。虽然纳米外壳中水的分子结构对科学和工业都特别感兴趣，但它需要具有纳米空间分辨率和亚ev能量灵敏度的精细光谱探针。石墨烯液体电池（GLCs）的特点是疏水石墨烯片间距相反，便于高分辨率透射电子显微镜（TEM）和电子能量损失光谱（EELS）测量紧密封装在GLC纳米容器中的100升水体积。我们对包裹在室温和低温下的薄GLCs中的水进行了原位TEM和EELS分析，以检查所含水分子的纳米级排列。同时定量的GLC厚度得出结论，氢键在增加水约束下增强。本研究结果证明了GLC纳米容器中含水流体纳米级化学表征的可行性，并为高约束条件下的水分子排列提供了新的见解。
Water is ubiquitous in natural systems, ranging from the vast oceans to the nanocapillaries in the earth crust or cellular organelles. In bulk or in intimate contact with solid surfaces, water molecules arrange themselves according to their hydrogen (H) bonding, which critically affects their short- and long-range molecular structures. Formation of H bonds among water molecules designates the energy levels of certain nonbonding molecular orbitals of water, which are quantifiable by spectroscopic techniques. While the molecular architecture of water in nanoenclosures is of particular interest to both science and industry, it requires fine spectroscopic probes with nanometer spatial resolution and sub-eV energy sensitivity. Graphene liquid cells (GLCs), which feature opposing closely spaced sheets of hydrophobic graphene, facilitate high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) measurements of attoliter water volumes encapsulated tightly in the GLC nanovessels. We perform in situ TEM and EELS analysis of water encased in thin GLCs exposed to room and cryogenic temperatures to examine the nanoscale arrangement of the contained water molecules. Simultaneous quantification of GLC thickness leads to the conclusion that H-bonding strengthens under increased water confinement. The present results demonstrate the feasibility of nanoscale chemical characterization of aqueous fluids trapped in GLC nanovessels and offer insights on water molecule arrangement under high-confinement conditions.