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

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.

The research to be carried out within the project will have a direct impact on other researchers and be of interest to the industry in the field of energy as well. For example, our findings will help developers of devices such as supercapacitors, rechargeable batteries, photovoltaics and fuel cells to design task-specific electrolytes. This will improve the efficiency and thus minimize fuel consumption and pollutant formation. As a consequence, our research has a great potential to have a sustainable impact in the longer term on the economy in the energy sector and an environmental impact as well as it may help to develop clean technologies for energy storage and conversion. Moreover, it aims at providing a basis for novel energy applications and hence means an opportunity of making the future society less dependent on fossil fuels.
Directly related to catalysis, the proposed research will also benefit the chemical industries. For example, it may open up new concepts for chemical reactors to produce for instance pharmaceuticals or fine chemicals with improved quality and less side-products and wastes. This would have significant economic, societal and environmental impact in the long term.
Of course, the researchers involved in the project will benefit as well. The interdisciplinary and international environment in which the project is carried out means a very special and invaluable training, in particular for the junior researchers (PhD students and post-docs) participating. This will be ensured by an exchange in which researchers of the UK group spend several months at the US institution and vise versa. This experience will help them making the next step in becoming independent researchers in the future. The senior researchers involved will benefit from becoming further established in their fields, but also from broadening their knowledge through the interdisciplinary work across the theoretical and experimental approaches.