Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie, Paris, 75005 Paris, France.
PASTEUR, École normale supérieure, PSL Research University, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France.
Chem Soc Rev. 2017 Dec 7;46(23):7421-7437. doi: 10.1039/c7cs00478h. Epub 2017 Oct 20.
We review the high pressure forced intrusion studies of water in hydrophobic microporous materials such as zeolites and MOFs, a field of research that has emerged some 15 years ago and is now very active. Many of these studies are aimed at investigating the possibility of using these systems as energy storage devices. A series of all-silica zeolites (zeosil) frameworks were found suitable for reversible energy storage because of their stability with respect to hydrolysis after several water intrusion-extrusion cycles. Several microporous hydrophobic zeolite imidazolate frameworks (ZIFs) also happen to be quite stable and resistant towards hydrolysis and thus seem very promising for energy storage applications. Replacing pure water by electrolyte aqueous solutions enables to increase the stored energy by a factor close to 3, on account of the high pressure shift of the intrusion transition. In addition to the fact that aqueous solutions and microporous silica materials are environmental friendly, these systems are thus becoming increasingly interesting for the design of new energy storage devices. This review also addresses the theoretical approaches and molecular simulations performed in order to better understand the experimental behavior of nano-confined water. Molecular simulation studies showed that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional and sufficiently open. In an extreme confinement situations such as in ferrierite zeosil, condensation seem to take place through a continuous supercritical crossing from a diluted to a dense fluid, on account of the fact that the first-order transition line is shifted to higher pressure, and the confined water critical point is correlatively shifted to lower temperature. These molecular simulation studies suggest that the most important features of the intrusion/extrusion process can be understood in terms of equilibrium thermodynamics considerations.
我们回顾了水在疏水性微孔材料（如沸石和 MOF）中的高压强制侵入研究，这一研究领域大约在 15 年前出现，现在非常活跃。这些研究中的许多旨在研究这些系统作为储能设备的可能性。一系列全硅沸石（zeosil）框架由于在多次水侵入-挤出循环后水解的稳定性而被认为适合可逆能量存储。一些疏水性微孔沸石咪唑酯骨架（ZIF）也非常稳定且耐水解，因此对于储能应用似乎非常有前途。用电解质水溶液代替纯水，可以通过高压侵入转变的位移将存储的能量增加近 3 倍。由于水溶液和微孔硅材料对环境友好，因此这些系统在设计新型储能设备方面变得越来越有趣。这篇综述还介绍了为了更好地理解纳米受限水中的实验行为而进行的理论方法和分子模拟。分子模拟研究表明，只要相互连接的孔结构是三维的且足够开放，水就会通过真正的一级相变发生冷凝。在 Ferrierite zeosil 等极端受限情况下，由于一级相变线被推高，受限水的临界点相应地被推低，冷凝似乎通过从稀释到密集流体的连续超临界交叉发生。这些分子模拟研究表明，侵入/挤出过程的最重要特征可以根据平衡热力学考虑来理解。
