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Isoelectronic Doping and External Electric Field Regulate the Gas-Separation Performance of Graphdiyne
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-01-17 , DOI: 10.1021/acs.jpcc.9b11062
Lei Fang 1 , Zexing Cao 1
Affiliation  

The first-principles calculations and molecular dynamics (MD) simulations have been used to explore the effects of boron nitride (BN) doping and an external electric field on the diffusion of gases (N2, CO, H2, CO2, and CH4) through a graphdiyne (GDY) membrane. BN-doped graphdiyne-like monolayers (GDY-BN and GDY-fBN) were predicted to have better permeability than the GDY membrane for the diffusion of these molecules and maintain high selectivity for hydrogen purification. The presence of an external electric field may regulate the diffusion behavior of CO2 and CO through the membrane, while other gas molecules are almost not influenced, which can improve the permselectivity toward gas separation. MD simulations reveal an unexpected temperature effect on gas diffusion through GDY-BN, which may be ascribed to a balance between the thermally driven translation and rotation motions. The rise in temperature increases the driving force for molecular translation through the membrane, but the thermal speedup of rotational motion may reduce the possibility of gases passing through the membrane in the optimal axial direction of molecules with the lowest diffusion barriers. The present results suggest that the gas-separation performance can be manipulated by regulating the charge distribution of the pore and using an external electric field.

中文翻译:

等电掺杂和外电场调节石墨二炔的气体分离性能

第一性原理计算和分子动力学(MD)模拟已用于探索氮化硼(BN)掺杂和外部电场对气体(N 2,CO,H 2,CO 2和CH)扩散的影响4)通过石墨二炔(GDY)膜。据预测,BN掺杂的石墨二炔样单层(GDY-BN和GDY-fBN)对于这些分子的扩散具有比GDY膜更好的渗透性,并保持较高的氢纯化选择性。外部电场的存在可能会调节CO 2的扩散行为气体和二氧化碳通过膜,而其他气体分子几乎不受影响,这可以提高对气体分离的渗透选择性。MD模拟显示出意外的温度影响气体通过GDY-BN扩散,这可能归因于热驱动平移和旋转运动之间的平衡。温度的升高增加了分子通过膜平移的驱动力,但是旋转运动的热加速可能会降低气体在具有最低扩散势垒的分子的最佳轴向上通过膜的可能性。目前的结果表明,可以通过调节孔的电荷分布并使用外部电场来控制气体分离性能。
更新日期:2020-01-17
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