Elucidating the Effects of Organic and Inorganic Cations on the Structure of the Electrochemical Double Layer and Electrocatalysis

With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professor Matthias Waegele of Boston College is investigating how the distribution of organic and inorganic cations in the electrochemical double layer (EDL) is influenced by the bulk composition of the electrolyte and how this distribution affects electrocatalytic reactions, including carbon dioxide reduction and hydrogen evolution. Efficient and selective electrocatalytic processes for converting electrical energy to chemical energy are essential for a sustainable economy.

However, many processes still lack the necessary energy efficiency and product selectivity for practical use. Recent studies indicate that catalytic activity can be enhanced by choosing the appropriate electrolyte cation. To advance this strategy, detailed knowledge of the impact of the supporting electrolyte’s cation on the EDL structure is required but is largely missing.

Professor Waegele and his students will use vibrational spectroscopy to examine the distributions of cations and the resulting EDL electric fields as a function of electrode potential. Their studies could provide insights into the key factors influencing the EDL structure and resulting catalytic activity for carbon dioxide reduction, hydrogen evolution, and other technologically relevant reactions.

Additionally, Professor Waegele’s team will offer educational opportunities for high school students.

The project team will employ surface-enhanced infrared absorption spectroscopy (SEIRAS) to probe the potential-dependent structure of the EDL. To this end, Professor Waegele’s group will use multiple vibrational reporters. Briefly, the team will measure how the accumulation of organic cations in the EDL is controlled by their properties, anion identity, and electrode material and characterize the emergent electric field with vibrational Stark spectroscopy.

The team will further develop and apply vibrational reporters as quantitative measures of the accumulation of inorganic cations. Lastly, the team will investigate the EDL environment that is experienced by key reaction intermediates in carbon dioxide reduction. The work could provide fundamental insights into the structure of the EDL by unraveling the relationships between cation distribution in the EDL and interfacial electrostatics during electrocatalysis.

Results will likely advance the understanding of the EDL under reaction conditions, where application of classical EDL theories is often inadequate. Further, the project could establish how the structure of the micro-environment influences catalysis. This information is essential for designing electrocatalytic interfaces that selectively and efficiently catalyze many technologically relevant reactions.

The project will provide training opportunities for graduate and undergraduate students and engage non-academic communities, particularly high school 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.