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Dynamic of water molecule in the nano-porous silica and its surface effect

纳米多孔二氧化硅中水分子的动态及其表面效应

基本信息

批准号：
18510093
负责人：
OTOMO Toshiya
金额：
$ 2.39万
依托单位：
High Energy Accelerator Research Organization
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

In this research, an in-situ water adsorption system was constructed and neutron quasi-elastic had been performed. New information concerning adsorbed water molecule in the nano-porous silica (FSM) were obtained by analysis based on Jump Diffusion Model.1) The dynamics of water molecules in the nano-pore can be analyzed by separating two types of molecules ; one is confined on the pore surface (monolayer water) and the other is free from the surface.2) The diffusion constant (～10^<-9>m^2s^<-1>) and activation energy (～2.5kcal/mol) of the monolayer water are about half of bulk water.3) The residential time before diffusion jumping is 5 times longer than bulk water.4) The other water shows similar diffusion behavior (～2.7×10^<-8>m^2s^<-1> and ～4.7kcal/mol) to bulk water.To understand the diffusion behavior in atomic level, neutron and X-ray diffraction had been performed. Diffraction profiles measured by in-situ adsorption technique show water adsorption behavior into the nano-pores but the structural analysis has not been finished yet. The glassy structure of FSM skeleton need to be investigated as well as controlling the content of hydrogen atoms and/or substitution to deuterium in the FSM. Inelastic scattering of FSM skeleton itself may be useful to understand the glassy structure.

本研究建立了一个原位水吸附系统，并进行了中子准弹性研究。基于跳跃扩散模型（Jump Diffusion Model）对纳米多孔二氧化硅（FSM）中的吸附水分子进行了分析，获得了新的信息：1）纳米孔中的水分子动力学可以通过分离两种类型的分子来分析：一种是限制在孔表面的分子（单层水），另一种是游离于孔表面的分子。2）纳米孔中的扩散常数（~ 10^ m^2s^）和活化能（~10^ m^2s ^）可以通过计算得到。3）<-9>纳米孔中的吸附水分子的扩散常数（~10^ m^2s^<-1>）和活化能（~ 10 ^m^2s ^（~2.5kcal/mol）的单层水约为本体水的一半。3）扩散跳跃前的停留时间是本体水的5倍。4）另一种水表现出与本体水相似的扩散行为（~2.7×10^<-8>m^2s^<-1>和~4.7kcal/mol）为了了解原子水平上的扩散行为，进行了中子和X射线衍射。原位吸附技术测得的衍射图显示了水在纳米孔中的吸附行为，但结构分析尚未完成。FSM骨架的玻璃态结构需要研究，以及控制FSM中氢原子的含量和/或氘的取代。FSM骨架本身的非弹性散射可能有助于理解玻璃态结构。