Separation selectivity and structural flexibility of graphene-like 2-dimensional membranes.
Separation selectivity and structural flexibility of graphene-like 2-dimensional membranes.
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DOI：
10.1039/c8cp00466h
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发表时间：
2018-07
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影响因子：
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通讯作者：
Liying Zhang;Chao Wu;Xiangdong Ding;Yong Fang;Jun Sun
中科院分区：
文献类型：
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作者：
Liying Zhang;Chao Wu;Xiangdong Ding;Yong Fang;Jun Sun
采用第一性原理计算，对具有相似孔径（约8 × 6 μ m）的多孔石墨烯、石墨炔衍生物（α/α2/β-石墨炔）和多孔氮化硼（BN）的单层膜分离戊烷异构体进行了评价。尽管它们的孔径稍大，但石墨炔衍生物仅允许线性戊烷分子穿过它们的天然孔，而相比之下，多孔石墨烯和BN膜仅阻挡二支化异构体，即，新戊烷分子。几何变化的分析表明，膜的结构柔性决定了渗透屏障。在分子的渗透过程中，刚性膜如石墨炔衍生物可能表现出与柔性多孔石墨烯和BN类似的变形;然而，前者的能量增加是后者的两倍。更重要的是，与柔性膜相比，通过刚性膜的分子经历约两倍的几何畸变和四倍的能量势垒增加。变形越大的通过分子和变形越小的刚性膜可以导致高得多的渗透屏障。我们的研究结果表明，多孔BN的灵活性是可比的多孔石墨烯，而石墨炔衍生物更刚性。
Single-layer membranes of porous graphene, graphyne derivatives (α/α2/β-graphyne), and porous boron nitride (BN) with similar pore sizes (approximately 8 × 6 Å) have been evaluated for separating pentane isomers using first-principles calculations. In spite of their slightly bigger pore sizes, graphyne derivatives only allow linear pentane molecules to go through their native pores, while in contrast porous graphene and BN membranes only block dibranched isomers, i.e., neopentane molecules. Analyses of the geometric changes reveal that the structural flexibility of the membrane determines the penetration barrier. During the penetration of molecules, rigid membranes like graphyne derivatives may exhibit similar distortion to flexible porous graphene and BN; however the energy increase for the former is twice that for the latter. More importantly, the passing molecules experience about two times geometry distortion and four times energy barrier increase when going through rigid membranes compared with flexible membranes. The more deformed passing molecule and the less deformed rigid membrane can result in a much higher penetration barrier. Our results show that the flexibility of porous BN is comparable to that of porous graphene while graphyne derivatives are much more rigid.