基于Ti原子杂化微孔晶体结构的CO_(2)吸附特性和电荷转移机理研究

Research on CO_(2) Adsorption Properties and Charge Transfer Mechanism of Microporous Crystal Structures Based on Ti Atom Hybridization

替换SIFSIX类杂化微孔材料的金属位点或有机配体可以合成大量具有不同孔径的化合物,TiF_(6)^(2-)配体对CO_(2)吸附和电荷转移特性的影响机理尚不充分。本研究以此为背景在SIFSIX-3-Zn的基础上将SiF_(6)^(2-)的Si原子替换为Ti原子,构建了TiFSIX-3-Fe和TiFSIX-3-Zn模型,通过DFT分析了TiFSIX-3-M(TiF_(6)^(2-)为离子配体,M为金属位点,M=Fe/Zn)中CO_(2)在孔道内的吸附与电荷转移行为,计算了孔道内的CO_(2)吸附位点、能带结构、吸附能、差分电荷密度、Mulliken电荷分布。研究结果表明:TiFSIX-3-Fe和TiFSIX-3-Zn具有更小的孔道体积,分别为1.26×10^(5)nm^(3)和1.22×10^(5)nm^(3)。Ti原子加入改善了TiFSIX-3-Fe的能带结构,但对TIFSIX-3-Zn影响不明显。Ti构建的两种模型的吸附能最高分别为-0.356 e V和-0.361 eV。差分电荷密度表明电荷从F原子附近向C原子转移,结合Mulliken布居分析得到构型中电荷转移数量分别增大至0.072 e和0.075 e,TiFSIX-3-Fe和TiFSIX-3-Zn的CO_(2)吸附和电荷转移特性显著增强。本工作为开发具有高效CO_(2)捕集能力的杂化微孔材料提供了理论指导。

Abundant compounds with different pore sizes can be synthesized by modifying the metal sites or inorganic pillar of SIFSIX hybrid microporous materials.The mechanism of the influence of TiF_(6)^(2-) pillar on the adsorption and charge transfer characteristic of CO_(2) is still insufficient.In this study,TiFSIX-3-Fe and TiFSIX-3-Zn are constructed.The adsorption and charge transfer characteristic of CO_(2) in TiFSIX-3-M(TiF_(6)^(2-) is inorganic pillar,M is metal atom,M=Fe,Zn)was analyzed by DFT.The adsorption sites,band structure,adsorption energy,differential charge density and Mulliken population were calculated.The results show that:TiFSIX-3-Fe and TiFSIX-3-Zn have smaller volume,which are 1.26×10^(5)nm^(3)and 1.22×10^(5)nm^(3),respectively.The addition of Ti atom improves the band structure of TiFSIX-3-Fe but has no obvious effect on Zn.The highest adsorption energy are−0.356 eV and−0.361 eV,respectively.The differential charge density indicates that the charge transfer is from F atom to C atom.Combined with Mulliken’s population,the charge transfer quantity increases to 0.072 e and 0.075 e,respectively.The addition of Ti atom significantly enhances the adsorption energy and charge transfer characteristics of CO_(2).This work provides theoretical guidance for the development of hybrid microporous materials with high CO_(2) capture characteristic.