Water dynamics in graphite oxide investigated with neutron scattering
Water dynamics in graphite oxide investigated with neutron scattering
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DOI：
10.1021/jp0641132
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发表时间：
2006-11-16
影响因子：
3.3
通讯作者：
Pieper, Joerg
中科院分区：
文献类型：
--
作者：
Buchsteiner, Alexandra;Lerf, Anton;Pieper, Joerg
氧化石墨是一种无机多层体系，它保留了石墨的层状结构，但不保留共轭键结构。过去几年，人们对氧化石墨的静态结构进行了详细的研究。这主要是通过NMR研究完成的，并导致了氧化石墨的新结构模型。氧化石墨的层间距随着湿度水平的增加而增加，从而导致碳层的不同间距在6至12埃的范围内。因此，水和官能团的不同类型的运动出现。关于水分子流动性的信息还不完整，但对于理解碳层的结构以及嵌入过程至关重要。在本文中，水合和温度依赖的氧化石墨的动态行为将使用的飞行时间谱仪NEAT在柏林的准弹性中子散射研究。嵌入水的特性在很宽的水化水平范围内不会改变。特别是层间水保持紧密结合，不显示任何平移运动。然而，在样品中有多余的水，水也分布在noninterlayer空隙，导致观察到的bulklike或承压水的额外运动。水合氧化石墨的动力学行为可以用一个一致的模型来描述，该模型结合了水分子运动和OH基团运动的两个双位点跳跃运动。
Graphite oxide is an inorganic multilayer system that preserves the layered structure of graphite but not the conjugated bond structure. In the past few years, detailed studies of the static structure of graphite oxide were carried out. This was mainly done by NMR investigations and led to a new structural model of graphite oxide. The layer distance of graphite oxide increases with increasing humidity level, giving rise to different spacings of the carbon layers in the range from 6 to 12 angstrom. As a consequence, different types of motions of water and functional groups appear. Information about the mobility of the water molecules is not yet complete but is crucial for the understanding of the structure of the carbon layers as well as the intercalation process. In this paper, the hydration- and temperature-dependent dynamic behavior of graphite oxide will be investigated by quasielastic neutron scattering using the time-of-flight spectrometer NEAT at the Hahn-Meitner-Institut Berlin. The character of the embedded water does not change over a wide range of hydration levels. Especially the interlayer water remains tightly bound and does not show any translational motion. In samples with excess water, however, the water is also distributed in noninterlayer voids, leading to the observation of additional motions of bulklike or confined water. The dynamic behavior of hydrated graphite oxide can be described by a consistent model that combines two two-site jump motions for the motions of the water molecules and the motions of OH groups.