CAREER: Elucidating the Interfacial Structure of Complex Solvents for Chemical Transformations

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The availability of high-performing solvents that function as absorbents, co-catalysts, and electrolytes is a critical and unmet need for advanced technologies such as integrated capture and conversion of carbon dioxide. This project will develop functionalized solvents that have high affinity to carbon dioxide as well as facilitate its efficient conversion to other useful products such as fuels. These complex solvents are hydrogen-bonded organic complex (HBOC) liquids with high concentrations of salts and often have molecular-scale structure and heterogeneity. The mechanisms of absorption and reactivity of carbon dioxide at the electrode-electrolyte interface are not well understood in these solvents. This project will explore the fundamental mechanisms that underpin absorption, interfacial liquid structure, and reactivity to inform future designs of integrated systems for chemical transformations. The knowledge gained has far-reaching applications in separations, catalysis, sensors, and other electrochemical processes. Through these applications, this research addresses the societal challenges of climate change, emission mitigation, waste utilization, and energy consumption. The educational goal of this CAREER project is to enhance students’ learning experience using visuals and to build science literacy through drawing. Visual illustrations of the scientific concepts of this project will be created for use as educational materials, which will be disseminated via publications, seminars, and public events. These activities will foster teamwork and strengthen ties with the local community in Cleveland through collaboration with the Cleveland Institute of Art.With support from both the Interfacial Engineering and Electrochemical Systems programs, this project will characterize the liquid structure of concentrated electrolytes at interfaces with electrified surfaces and quantitatively assess the structural impact on charge distribution, thermodynamics, and reaction mechanisms in separation processes and electrochemical reactions. The solvation structure and reactive state of the carbon dioxide model compound both within and at HBOC electrolyte-electrode interfaces will be investigated by spectroscopy, neutron and X-ray reflectivity, and electroanalytical techniques. These studies will provide a basis for understanding the structure and dynamics of the behavior of small molecules in complex solvents. More specifically, the following scientific questions will be answered: (1) What is the physical environment of the carbon dioxide solvate complex at the electrode-electrolyte interface? and (2) What is the impact of the interface structure on electron and proton transfer and selectivity of the carbon dioxide reduction mechanism? The results from this study will contribute to the understanding of electrical double layer structures of HBOC electrolytes, as they cannot be explained by the traditional models suitable for dilute systems. The results will also impact the discussions on the role of the electrolyte in carbon dioxide co-catalysis. The project will apply the STEM educational concept of ‘learning by drawing’ and artistic illustration in undergraduate and graduate-level courses and public outreach. Learning by drawing is expected to enhance student engagement in engineering courses, improve visual literacy, promote knowledge retention, increase diversity among students pursuing STEM-related fields, as well foster interdisciplinary communication between art and engineering students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.