Nanosheets are finely structured two-dimensional materials and have great potential for innovation. They are fixed on top of each other in layered crystals, and must first be separated from each other so that they can be used, for example, to filter gas mixtures or for efficient gas barriers. A research team at the University of Bayreuth has now developed a gentle, environmentally-friendly process for this difficult process of delamination that can even be used on an industrial scale. This is the first time that a crystal from the technologically attractive group of zeolites has been made usable for a broad field of potential applications.
The delamination process developed in Bayreuth under the direction of Prof. Dr. Josef Breu is characterized by the fact that the structures of the nanosheets isolated from each other remain undamaged. It also has the advantage that it can be used at normal room temperature. The researchers present their results in detail in Science Advances.
The two-dimensional nanosheets, which lie on top of each other in layered crystals, are held together by electrostatic forces. In order for them to be used for technological applications, the electrostatic forces must be overcome, and the nanosheets detached from each other. A method particularly suitable for this is osmotic swelling, in which the nanosheets are forced apart by water and the molecules and ions dissolved in it. So far, however, it has only been possible to apply it to a few types of crystals, including some clay minerals, titanates, and niobates. For the group of zeolites, however, whose nanosheets are highly interesting for the production of functional membranes due to their silicate-containing fine structures, the mechanism of osmotic swelling has not yet been applicable.
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