Effect of graphene oxide (GO) nanosheet sizes, pinhole defects and non-ideal lamellar stacking on the performance of layered GO membranes: an atomistic investigation.
Effect of graphene oxide (GO) nanosheet sizes, pinhole defects and non-ideal lamellar stacking on the performance of layered GO membranes: an atomistic investigation.
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DOI：
10.1039/c9na00235a
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发表时间：
2019-08-06
影响因子：
4.7
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中科院分区：
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利用平衡分子动力学（MD）模拟研究了纳米片的非理想性（即针孔缺陷和非理想层状堆叠）对尺寸差异化氧化石墨烯（GO）层压板性能的影响。随着组成GO纳米片的尺寸的增加，层状GO膜的水渗透性降低并且盐截留率增加。但随着非理想性的加入，这些膜之间的水渗透性的差异显著减小。GO纳米片上的针孔为跨片流动提供更短的路线，从而增加膜的透水性。没有针孔缺陷的纳米片的非理想堆叠导致水渗透性的轻微降低，这是因为膜内部的渗透途径被阻塞。然而，在针孔缺陷的情况下，非理想堆叠变得有利于水渗透通过层状GO膜;因为此时非理想堆叠导致在膜内部形成空隙，其充当较短渗透路径的路线。这些非理想性的影响对于由大的GO纳米片组成的层状GO膜更显著。尽管由于这些非理想性，通过层状GO膜的水渗透性大大增强（约10倍），但盐截留率的相应变化非常低（<2%）。沿着组成氧化石墨烯（GO）纳米片的尺寸，GO纳米片上存在的针孔缺陷和非理想的层状堆叠在层状GO膜的性能中起着至关重要的作用。
The effect of non-idealities, namely pinhole defects and non-ideal lamellar stacking of nanosheets, on the performance of size-differentiated graphene oxide (GO) laminates is investigated using equilibrium molecular dynamics (MD) simulations. With the increase in sizes of the constituent GO nanosheets the water permeability of the layered GO membranes decreases and salt rejection increases. But with the inclusion of non-idealities the difference in water permeability between these membranes substantially reduced. The pinholes on the GO nanosheets provide shorter routes for trans-sheet flow, thereby increasing the water permeability of the membranes. The non-ideal stacking of the nanosheets without pinhole defects results in slight reduction in water permeability because of blockage of permeation pathways inside the membranes. However, with pinhole defects non-ideal stacking becomes favorable for water permeation through the layered GO membranes; as this time the non-ideal stacking leads to formation of voids inside the membranes, which act as routes for shorter permeation pathways. The effect of these non-idealities is more significant for layered GO membranes composed of large GO nanosheets. Although the water permeability through the layered GO membrane is greatly enhanced because of these non-idealities (about 10 times), the corresponding variation in the salt rejection is very low (<2%). Along with the size of the constituent graphene oxide (GO) nanosheets, the pinhole defects present on the GO nanosheets and non-ideal lamellar stacking play a crucial role in the performance of layered GO membranes.
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