Doping of alkali, alkaline-earth, and transition metals in covalent-organic frameworks for enhancing CO2 capture by first-principles calculations and molecular simulations.
Doping of alkali, alkaline-earth, and transition metals in covalent-organic frameworks for enhancing CO2 capture by first-principles calculations and molecular simulations.
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DOI：
10.1021/nn100962r
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发表时间：
2010-06
期刊：
影响因子：
17.1
通讯作者：
J. Lan;D. Cao;Wenchuan Wang;B. Smit
中科院分区：
文献类型：
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作者：
J. Lan;D. Cao;Wenchuan Wang;B. Smit
我们使用多尺度模拟方法，它结合了第一性原理计算和巨正则蒙特卡罗模拟，全面研究了一系列碱金属（Li，Na和K），碱土金属（Be，Mg和Ca）和过渡金属（Sc和Ti）在纳米多孔共价有机框架（COFs）中的掺杂，以及掺杂金属对CO2捕获的影响。结果表明，在所研究的金属中，Li、Sc和Ti能与COFs稳定结合，而Be、Mg和Ca不能与COFs稳定结合，因为Be、Mg和Ca与COFs的结合很弱。此外，Li、Sc和Ti可以显著提高COF中CO2的吸收。然而，与Sc和Ti的CO2分子的结合能超过了化学吸附的下限，因此，遭受解吸的困难。通过以上对比研究发现，在所研究的所有金属中，Li是COFs捕集CO2的最佳表面改性剂。因此，我们进一步研究了CO2在Li掺杂COFs中的吸收。我们的模拟结果表明，在298 K和1巴，过量CO2吸收的锂掺杂COF-102和COF-105达到409和344 mg/g，这是在未掺杂的约8倍和4倍，分别。当压力增加到40巴时，Li掺杂的COF-102和COF-105的CO2吸收在298 K下分别达到1349和2266 mg/g，这是迄今为止报道的最高分数之一。总之，在多孔COF中掺杂金属提供了用于增强CO2捕获的有效方法。
We use the multiscale simulation approach, which combines the first-principles calculations and grand canonical Monte Carlo simulations, to comprehensively study the doping of a series of alkali (Li, Na, and K), alkaline-earth (Be, Mg, and Ca), and transition (Sc and Ti) metals in nanoporous covalent organic frameworks (COFs), and the effects of the doped metals on CO2 capture. The results indicate that, among all the metals studied, Li, Sc, and Ti can bind with COFs stably, while Be, Mg, and Ca cannot, because the binding of Be, Mg, and Ca with COFs is very weak. Furthermore, Li, Sc, and Ti can improve the uptakes of CO2 in COFs significantly. However, the binding energy of a CO2 molecule with Sc and Ti exceeds the lower limit of chemisorptions and, thus, suffers from the difficulty of desorption. By the comparative studies above, it is found that Li is the best surface modifier of COFs for CO2 capture among all the metals studied. Therefore, we further investigate the uptakes of CO2 in the Li-doped COFs. Our simulation results show that at 298 K and 1 bar, the excess CO2 uptakes of the Li-doped COF-102 and COF-105 reach 409 and 344 mg/g, which are about eight and four times those in the nondoped ones, respectively. As the pressure increases to 40 bar, the CO2 uptakes of the Li-doped COF-102 and COF-105 reach 1349 and 2266 mg/g at 298 K, respectively, which are among the reported highest scores to date. In summary, doping of metals in porous COFs provides an efficient approach for enhancing CO2 capture.