Square ice in graphene nanocapillaries
Square ice in graphene nanocapillaries
复制标题
石墨烯纳米毛细管中的方冰
DOI：
10.1038/nature14295
复制
发表时间：
2015-03-26
期刊：
影响因子：
64.8
通讯作者：
Grigorieva, I. V.
中科院分区：
文献类型：
--
作者：
Algara-Siller, G.;Lehtinen, O.;Grigorieva, I. V.
大量的水以多种形式存在，包括液体，蒸汽和许多结晶和非晶相的冰，六边形的冰是迷人的各种雪花的原因。不太引人注意但同样普遍存在的是吸附在界面上并限制在微观孔隙中的水。这种低维水决定了材料科学、地质学、生物学、摩擦学和纳米技术中各种现象的各个方面。理论表明，吸附水和承压水有许多可能的相，在这里，我们报告高分辨率电子显微镜成像的水锁定在两个石墨烯片，疏水限制的一个典型例子。观察结果表明，在室温下的nanobolized水形成“方冰”-一个相位具有对称性定性不同于传统的四面体几何的水分子之间的氢键。方冰具有高堆积密度，晶格常数为2.83 μ m，可以组装成双层和三层微晶。分子动力学模拟表明，方冰应该存在于疏水纳米通道内，独立于其确切的原子性质。
Bulk water exists in many forms, including liquid, vapour and numerous crystalline and amorphous phases of ice, with hexagonal ice being responsible for the fascinating variety of snowflakes,. Much less noticeable but equally ubiquitous is water adsorbed at interfaces and confined in microscopic pores. Such low-dimensional water determines aspects of various phenomena in materials science, geology, biology, tribology and nanotechnology,,,,,. Theory suggests many possible phases for adsorbed and confined water,,,,,,,,, but it has proved challenging to assess its crystal structure experimentally,,,,,,. Here we report high-resolution electron microscopy imaging of water locked between two graphene sheets, an archetypal example of hydrophobic confinement. The observations show that the nanoconfined water at room temperature forms ‘square ice’—a phase having symmetry qualitatively different from the conventional tetrahedral geometry of hydrogen bonding between water molecules. Square ice has a high packing density with a lattice constant of 2.83 Å and can assemble in bilayer and trilayer crystallites. Molecular dynamics simulations indicate that square ice should be present inside hydrophobic nanochannels independently of their exact atomic nature.