ICC: A Combined Computational and Spectroscopic Study of Structure and Charge Transfer Dynamics of Ionic Liquids in Heterogeneous Environments

离子液体(ILS)是一类较新的材料，在能源设备中具有很大的应用潜力。本文提出的合作研究旨在通过计算化学(量子化学和模拟)和光谱学(红外、拉曼、X射线和非弹性中子散射)的综合努力，定量了解离子液体及其与有机共溶剂的混合物在纳米环境中的结构和动力学，包括与微孔石墨材料和金属-有机骨架(MOF)的界面。我们的重点是：(1)离子和共溶剂分子各自扮演的角色及其相互作用和微孔在调节离子液体的结构和动力学性质中的作用；(2)通过振动、X射线和非弹性中子散射实验测量离子液体的电子结构和电荷转移性质；(3)分析离子液体的电子结构和电荷转移性质及其随孔内溶剂化结构的变化。通过协同整合美国和英国小组的互补优势，拟议的研究将提供新的化学见解，从而促进我们对与技术相关的IL-石墨烯和相关界面系统的基本理解，这些系统在能量存储和转换设备中有广泛的应用，如超级电容器、充电电池、光伏和燃料电池，以及在催化剂中。美国小组将进行MD模拟，并分析ILS(及其与有机添加剂的混合物)在微孔MOF和碳环境中的结构和动力学。利用所获得的结构信息，他们将进行量子化学计算，以分析ILS的振动光谱，并研究离子在表面附近的电荷转移。英国研究小组将使用振动、X射线和非弹性中子散射光谱来研究相同的系统，以获得对分子相互作用和界面结构的全面了解。通过对计算结果和实验结果的详细比较，将确定真实体系中离子(和助溶剂分子)的分子构象，并对测量的光谱进行结构解释。这将对离子和非均相环境的相互作用如何在振动光谱和X射线光谱中表现出来提供重要的解释。它还将提供分子水平的洞察，了解由纳米级环境引起的ILS的结构变化如何影响其化学反应。通过对外国合作者实验室的长期研究访问，拟议的合作将为参与该项目的初级科学家提供极好的培训和成长机会。特别是，在不同的研究和文化环境中与具有完全不同专长(即理论与实验)的人进行积极合作将是一次宝贵的经验，不仅将加深和拓宽初级研究人员的技术技能和科学知识，而且还将加深和拓宽他们对科学及其全球化的看法。这项研究的主要成果将被纳入卡内基梅隆大学开发的基于网络的化学教育软件ChemCollective中。这将有助于将能源领域的研究成果传播给更广泛的受众，包括本科生和高中生。这也将有助于提高他们对能源和可持续发展的认识。

Ionic liquids (ILs) are a relatively new class of materials with great potential for applications in energy devises. The collaborative research proposed here aims at obtaining a quantitative understanding of structure and dynamics of ionic liquids and their mixtures with organic co-solvents in nano-sized environments, including interfaces with microporous graphitic materials and metal-organic frameworks (MOFs), via a combined effort in computational chemistry (quantum chemistry and simulations) and spectroscopy (IR, Raman, X-ray and inelastic neutron scattering). Our primary focuses are: (1) respective roles played by ions and co-solvent molecules and their interplay as well as roles by micropores in modulating structural and dynamic properties of ILs, (2) their measurements via vibrational, X-ray and inelastic neutron scattering experiments and (3) analysis of electronic structure and charge transfer properties of ILs and their variations with solvation structures inside the pores. By integrating complementary strengths of US and UK groups synergistically, the proposed research will provide novel chemical insights into, and thus advance our fundamental understanding of, technologically-relevant IL-graphene and related interfacial systems that have broad applications in energy storage and conversion devices, such as supercapacitors, rechargeable batteries, photovoltaics and fuel cells, as well as in catalysis.The US group will perform MD simulations and analyze structure and dynamics of ILs (and their mixtures with organic additives) in microporous MOF and carbon environments. Using the structural information thus obtained, they will perform quantum chemistry calculations to analyze vibrational spectra of ILs and investigate charge transfer of ions near the surface. The UK groups will investigate the same systems using vibrational, X-ray and inelastic neutron scattering spectroscopy to obtain a comprehensive understanding of molecular interactions and structures at the interface. Through a detailed comparison of computational and experimental results, molecular conformations of ions (and cosolvent molecules) in the real system will be identified and a structural interpretation of the measured spectra will be made. This will shed important light on how interactions of ions and heterogeneous environments are manifested in vibrational and X-ray spectra. It will also provide molecular-level insight into how structural changes of ILs induced by nano-scale environments influence their chemical reactivity.Through extended research visits to the foreign collaborators' labs, the proposed collaboration will provide excellent training and growth opportunities for junior scientists involved in the project. In particular, active collaboration with people with totally different expertise (i.e., theory vs experiments) in different research and cultural environments will be an invaluable experience that would both deepen and broaden not only technical skills and scientific knowledge of junior researchers but also their perspectives on science and its globalization. Key results of the research will be incorporated into web-based chemistry educational software, ChemCollective, developed at Carnegie Mellon University. This will help to disseminate the outcome of the research in the energy context to a broader audience, including undergraduate and high school students. This will also help to increase their awareness of energy and sustainability.