Important Progress in the Study of Graphite Oxide Membrane

The precise regulation of the spacing of graphene oxide membranes is the key to its application in water treatment, ion/molecular separation, and battery/capacitance. However, the precise "binding" of graphene oxide nanoparticles into graphene oxide films and the fixing of layer spacing is a very challenging task. Under the funding of the National Natural Science Foundation Project(project numbers: 11290164, 41430644, 21490585, 1157 4339, 1140 4361, 21476107, 11722548), Fanghaiping of the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences, Wuminghong Nanjinggongyedaxuejinwanqin of Shanghai University, and Chen Nanjinggongyedaxuejinwanqin of the Chinese Academy of Sciences, This paper proposes and realizes the precise regulation of the spacing of graphene oxide films by the water hydrated ions themselves. The membrane exhibits excellent ion screening and seawater desalination properties. The related work was titled "Ion SievinGraphene OxideMembranesviacriCommission InterlayerSpaging"(cationic regulation of graphene oxide membrane spacing for ion screening) and was published online on October 9 on Nature. Original link: Http://www.nature.com/nature/journal/vaop/ncurrent/full/nature24044.

Fanghaiping's team proposed that the ions themselves in the solution can effectively control the spacing of the graphene oxide film and perform corresponding theoretical simulation calculations. They used Shanghai light source X-ray small-angle scattering(BL16B1), fine absorption spectrum(BL14W1), and ultraviolet to confirm the presence of hydrated ion-π interactions between ions and aromatic rings in graphene sheets. This interaction supports the graphene oxide sheet like a "bridge pier", and hydrated ions of different sizes are equivalent to "bridge piers" of different sizes, which can accurately regulate the spacing of layers. The Wuminghong team successfully realized and observed the specific layer spacing after the interaction of the graphene oxide film with different Ionic solutions. The spacing can be as small as about one nanometer, and the corresponding membrane spacing after different ions is different at the Emi level. Jinwanqin's team designed and prepared a series of porous ceramics supported by hydrated ions to achieve accurate screening of different ions. For potassium ions with a minimum hydration diameter, due to the weak hydration layer of potassium ions, the hydration layer after entering the graphene oxide membrane deforms, resulting in a particularly small layer spacing. In this way, the graphene oxide film soaked in potassium ion solution can effectively intercept all ions in the salt solution, including potassium ions themselves, but it can still pass through water molecules effectively. This study not only provides theoretical and technical guidance for the design and preparation of graphene oxide films, but also opens up new ideas for the research of other two-dimensional materials in the field of separation films.

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