Tunable Hydrogen Separation in sp鈥搒p2 Hybridized Carbon Membranes: A First-Principles Prediction

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• 作者：Hongyu Zhang ; Xiujie He ; Mingwen Zhao ; Meng Zhang ; Lixia Zhao ; Xiaojuan Feng ; Youhua Luo
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：August 9, 2012
• 年：2012
• 卷：116
• 期：31
• 页码：16634-16638
• 全文大小：334K
• 年卷期：v.116,no.31(August 9, 2012)
• ISSN：1932-7455

文摘

First-principles calculations are carried out to investigate the hydrogen separation characteristics of two-dimensional carbon allotropes consisting of sp- and sp²-hybridized carbon atoms, i.e., graphyne, graphdiyne, and rhombic-graphyne. The selectivities for H₂ over several gas molecules, including CO, N₂, and CH₄, are found to be sensitive to the pore sizes and shapes. The penetration barriers generally decrease exponentially with the pore sizes. Our results reveal that graphyne with small pores is unsuitable for the purpose of hydrogen separation. Graphdiyne, with larger pores, exhibits a high selectivity (10⁹) for hydrogen over large gas molecules such as CH₄, but a relatively low selectivity (10³) over small molecules such as CO and N₂. The large differences in diffusion barriers for molecules penetration through a rhombic-graphyne monolayer, which possesses pore size in between that of graphyne and graphdiyne, lead to a high selectivity (>10¹⁶) for hydrogen separation from the others. The results suggest that the abundant pores of different sizes in these carbon allotropes make them ideal molecular sieves for gas separation applications directed toward different separation needs and objectives.