Wang Mi, Wang Yanlei, Wang Chenlu, Gan Zhongdong, Huo Feng, He Hongyan, Zhang Suojiang
Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Phys Chem Lett. 2021 Jul 8;12(26):6078-6084. doi: 10.1021/acs.jpclett.1c01114. Epub 2021 Jun 25.
Revealing the structure and behavior of confined ionic liquids (ILs) is essential for their applications in green chemical processes. Here, we explore the electroconductivity (σ) and ionic correlation of imidazole ILs confined in graphene nanochannels via joint molecular dynamics simulation and theoretical analysis. The ideal and actual σ of ILs are first calculated, showing a growing tendency and up to the bulk value as the nanochannel size ranges from 1 to 10 nm. To account for the ionic correlation, the ionicity was determined by the ratio of the actual to ideal σ, reflecting the average fraction of free ions in the confined ILs. Amazingly, the ionicity of all three ILs shows an abnormal changing tendency, which first increases and reaches the maximum at 2 nm and then decreases to the bulk value. The conformational analysis, pair dissociating energy, and residence time are further obtained, proving that the abnormal enhanced ionicity should be attributed to the structure reconstruction of ILs near the graphene wall. The analytical model of ionicity herein can guide the rational design of efficient IL-based nanoporous electrodes and solid catalysts.
揭示受限离子液体（ILs）的结构和行为对于其在绿色化学过程中的应用至关重要。在此，我们通过联合分子动力学模拟和理论分析，探索了限制在石墨烯纳米通道中的咪唑离子液体的电导率（σ）和离子相关性。首先计算了离子液体的理想电导率和实际电导率，结果表明，随着纳米通道尺寸从1纳米增加到10纳米，电导率呈增长趋势并最终达到本体值。为了解释离子相关性，通过实际电导率与理想电导率的比值确定离子性，该比值反映了受限离子液体中自由离子的平均比例。令人惊讶的是，所有三种离子液体的离子性均呈现出异常变化趋势，即先增加并在2纳米处达到最大值，然后降至本体值。进一步获得了构象分析、对解离能和停留时间，证明异常增强的离子性应归因于石墨烯壁附近离子液体的结构重构。本文提出 的离子性分析模型可为基于离子液体的高效纳米多孔电极和固体催化剂的合理设计提供指导。
