Dhali Rama, John Chris, Swathi Rotti Srinivasamurthy
School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram , 695551 Kerala , India.
J Phys Chem A. 2019 Aug 29;123(34):7499-7506. doi: 10.1021/acs.jpca.9b06677. Epub 2019 Aug 20.
The remarkable performance of carbon membranes for the selective passage of various species has led to extensive research in designing smart membranes. The mechanical stability of graphene in conjunction with the excellent host-guest chemistry of crown ethers makes the recently synthesized family of crown ether-embedded graphene nanomeshes promising candidates for sieving applications. Inspired by the excellent control over pore architectures offered by such nanomeshes, we investigate the abilities of crown ether-embedded graphene nanomeshes for noble gas separation by the size-sieving mechanism and for He isotope separation by the quantum sieving mechanism. Unlike the previous studies that employ either a finite-difference approach or a wave packet approach, we employ an analytical Eckart potential approach to calculate the tunneling probabilities. Using tunneling-corrected transition-state theory, we examine the competing nature of the zero-point energy effects and tunneling effects in governing the total quantum transmission of the isotopes. Our analysis of the permeation barriers, diffusion rates, transmission probabilities, permeabilities, and selectivities suggests that crown ether-embedded graphene nanomeshes are a class of promising carbon membranes for He isotope separation.
碳膜在各种物质的选择性传输方面的卓越性能引发了对设计智能膜的广泛研究。石墨烯的机械稳定性与冠醚出色的主客体化学性质相结合，使得最近合成的嵌入冠醚的石墨烯纳米网成为筛分应用的有前景的候选材料。受此类纳米网对孔结构的出色控制的启发，我们研究了嵌入冠醚的石墨烯纳米网通过尺寸筛分机制进行稀有气体分离以及通过量子筛分机制进行氦同位素分离的能力。与以往采用有限差分法或波包法的研究不同，我们采用解析埃卡特势方法来计算隧穿概率。利用隧穿校正的过渡态理论，我们研究了零点能效应和隧穿效应在控制同位素总量子传输中的竞争性质。我们对渗透势垒、扩散速率、传输概率、渗透率和选择性的分析表明，嵌入冠醚的石墨烯纳米网是一类用于氦同位素分离的有前景的碳膜。
