化工学报 ›› 2023, Vol. 74 ›› Issue (9): 3665-3680.DOI: 10.11949/0438-1157.20230489

• 离子液体与绿色过程专栏 • 上一篇    下一篇

离子液体界面极化及其调控氢键性质的分子机理

陆俊凤1,2(), 孙怀宇1, 王艳磊1,2(), 何宏艳1,2   

  1. 1.沈阳化工大学化学工程学院,辽宁 沈阳 110142
    2.中国科学院过程工程研究所,离子液体清洁过程北京市重点实验室,北京 100190
  • 收稿日期:2023-05-16 修回日期:2023-07-13 出版日期:2023-09-25 发布日期:2023-11-20
  • 通讯作者: 王艳磊
  • 作者简介:陆俊凤(1994—),女,硕士研究生,lujunfeng@ipe.ac.cn
  • 基金资助:
    北京市科技新星计划项目(2021016);江苏省水处理新材料与污水资源化工程实验室项目(SDHY2114)

Molecular understanding of interfacial polarization and its effect on ionic liquid hydrogen bonds

Junfeng LU1,2(), Huaiyu SUN1, Yanlei WANG1,2(), Hongyan HE1,2   

  1. 1.School of Chemical Engineering, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China
    2.Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2023-05-16 Revised:2023-07-13 Online:2023-09-25 Published:2023-11-20
  • Contact: Yanlei WANG

摘要:

离子液体在电极界面处的结构及行为对其在超级电容器、固载催化剂等实际化工应用中有重要的影响。采用第一性原理计算结合理论分析研究了7种咪唑类离子液体在常见二维固体石墨烯、氮化硼、二硫化钼表面极化的分子机理及其对离子液体氢键的微观作用机制。结果表明,当离子液体在这三种二维表面吸附时会发生电荷转移和轨道相互作用,导致了显著的表面极化作用,且吸附能和电荷转移数值越大,表面极化作用越强。进一步分析了二维表面离子液体氢键的键长、键角、键序和键能,发现表面极化作用会显著削弱离子液体氢键。对于不同离子液体红外光谱的计算结果也验证了氢键被削弱的趋势。最后,通过SPSS软件对表面极化作用和离子液体氢键强度间的关系进行了定量解析,发现表面极化作用与氢键强度呈负相关关系。本文关于离子液体氢键的定量分析不仅有助于理解离子液体-固体表面作用的分子机理,而且可为离子液体在实际化工过程的应用提供理论支撑。

关键词: 离子液体, 绿色化工, 界面作用, 二维材料, 氢键

Abstract:

The structure and behavior of ionic liquid (IL) at the electrode interface have an important impact on their practical chemical applications such as supercapacitors and immobilized catalysts. In these applications, the interactions between IL with solid surfaces are common. Understanding the effect of the interfacial interactions on hydrogen bonds of IL is crucial for their practical chemical applications. However, due to the diversity of IL and solid surfaces, as well as the coexistence and coupling of many types of interactions on the surface, the effects of interfacial polarization on hydrogen bonds and the quantitative relationship between them are not clear. In this work, the first-principles calculations were performed to investigate the molecular mechanism of interfacial polarization and its influence on the hydrogen bonds for seven imidazole-based IL at the two-dimensional (2D) solid surfaces. The 1-ethyl-3-methylimidazolium (Emim]+) was selected as the cation for the study, used as electrolytes widely owing to their excellent conductivity, quasi-planar structure, and enhanced electrochemical properties. It was paired with seven anions, including [Cl]-, [Br]-, thiocyanate ([SCN]-), dicyanamide ([DCA]-), dicyanoboranuide ([B(H2CN2)]-), tricyanomethanide ([TCM]-) and tetracyanoborate ([TCB]-). The typical three 2D materials, including graphene (Gra), boron nitride (BN), and molybdenum disulfide (MoS2) were chosen as the solid surfaces. The results showed that charge transfer and orbital interaction would occur when ionic liquids are adsorbed on these three 2D surfaces, which further resulted in significant interfacial polarization. Its strength also increased with the decrease of the adsorption energy of IL on the 2D surfaces. Moreover, the change of IL hydrogen bonds on surfaces was described by the bond length, bond angle, bond order, and bond energy. It was found that the interfacial polarization would weaken the strength of HBs, where the strength of hydrogen bonds reduced notably as the IL lost more charge. And the infrared spectra of IL on solid surfaces were also calculated to confirm the evolution of hydrogen bonds with the interfacial polarization. Finally, the canonical correlation analysis was applied to construct a correlating model involving different factors related to the hydrogen bonds at the solid surface, proving that interface polarization was negatively correlated with the hydrogen bond strength. These quantitative results on the hydrogen bonds of IL can not only help understand the molecular mechanism of IL-solid interface but also be beneficial for the rational design of IL toward high-performance applications.

Key words: ionic liquid, green chemical engineering, interface interaction, 2D materials, hydrogen bond

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