1School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China 2Collaborative Innovation Center of Light Manipulations and Applications, Shandong Normal University, Jinan 250358, China 3College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes (Ministry of Education), Shandong Normal University, Jinan 250014, China
Abstract：Through atomic molecular dynamics simulations, we investigate the performance of two graphenic materials, boron (BC$_{3}$) and nitrogen doped graphene (C$_{3}$N), for seawater desalination and salt rejection, and take pristine graphene as a control. Effects of inter-layer separation have been explored. When water is filtered along the transverse directions of three-layered nanomaterials, the optimal inter-layer separation is 0.7–0.9 nm, which results in high water permeability and salt obstruction capability. The water permeability is considerably higher than porous graphene filter, and is about two orders of magnitude higher than commercial reverse osmosis (RO) membrane. By changing the inter-layer spacing, the water permeability of three graphenic layered nanomaterials follows an order of C$_{3}$N $\ge$ GRA $>$ BC$_{3}$ under the same working conditions. Amongst three nanomaterials, BC$_{3}$ is more sensitive to inter-layer separation which offers a possibility to control the water desalination speed by mechanically changing the membrane thickness. This is caused by the intrinsic charge transfer inside BC$_{3}$ that results in periodic distributed water clusters around the layer surface. Our present results reveal the high potentiality of multi-layered graphenic materials for controlled water desalination. It is hopeful that the present work can guide design and fabrication of highly efficient and tunable desalination architectures.
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2020, Vol. 37 
