Vogel Dayton J, Nenoff Tina M, Rimsza Jessica M
Computational Materials and Data Science Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
Material, Physical and Chemical Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
ACS Omega. 2022 Feb 22;7(9):7963-7972. doi: 10.1021/acsomega.1c07041. eCollection 2022 Mar 8.
Barely porous organic cages (POCs) successfully separate hydrogen isotopes (H/D) at temperatures below 100 K. Identifying the mechanisms that control the separation process is key to the design of next-generation hydrogen separation materials. Here, molecular dynamics (AIMD) simulations are used to elucidate the mechanisms that control D and H separation in barely POCs with varying functionalization. The temperature and pore size dependence were identified, including the selective capture of D in three different CC3 structures (RCC3, CC3-S, and 6ET-RCC3). The temperature capture trend was reversed for the 6ET-RCC3 structure, identifying that the D and H escape mechanisms are unique in highly functionalized systems. Analysis of calculated isotope velocities identified effective pore sizes that extend beyond the pore opening distances, resulting in increased capture in minimally functionalized CC3-S and RCC3. In a highly functionalized POC, 6ET-RCC3, higher velocities of the H isotopes were calculated moving through the restricted pore compared to the rest of the system, identifying a unique molecular behavior in the barely nanoporous pore openings. By using AIMD, mechanisms of H and D separation were identified, allowing for the targeted design of future novel materials for hydrogen isotope separation.
几乎无孔的有机笼状物（POCs）在低于100K的温度下成功分离氢同位素（H/D）。确定控制分离过程的机制是设计下一代氢分离材料的关键。在此，采用分子动力学（AIMD）模拟来阐明在具有不同功能化的几乎无孔的POCs中控制D和H分离的机制。确定了温度和孔径依赖性，包括在三种不同的CC3结构（RCC3、CC3-S和6ET-RCC3）中对D的选择性捕获。6ET-RCC3结构的温度捕获趋势相反，这表明在高度功能化的系统中D和H的逸出机制是独特的。对计算出的同位素速度的分析确定了有效孔径，其延伸超出了孔径开口距离，导致在功能最少的CC3-S和RCC3中捕获增加。在高度功能化的POC 6ET-RCC3中，与系统的其余部分相比，计算出H同位素通过受限孔移动的速度更高，这表明在几乎无孔的孔开口中存在独特的分子行为。通过使用AIMD，确定了H和D分离的机制，从而为未来用于氢同位素分离的新型材料的靶向设计提供了可能。
