Dielectric Relaxation Spectroscopy to Study Ionization Effects of Nanoconfined Water and Weak and Strong Aqueous Electrolytes

Description:
While bulk properties of water are well understood the dielectric properties of water under nano-confinement and in the presence of electric fields are not. In addition, aqueous electrolytes are ubiquitous but their dynamic structure still lacks clarity. However, the direct access to the sub-picosecond dynamics in aqueous electrolytes is limited, which explains why most of the models are based on static conductivity data. In our original research, I will report the first systematic experimental comparative study of the electrical properties of nanoconfined water and on ionization effects of weak and strong electrolytes over a wide frequency and concentration ranges. Our new results using broadband dielectric spectroscopy reveal new aspects of the dynamic structure of nanoconfined water that show anomalously high protonic conductivity [1]. Follow on studies to this work demonstrates that water confined to carbon-based materials changes its structure and dynamics, allowing for efficient electrochemical energy storage without using additional electrolytes as the ionic carrier. For aqueous weak and strong electrolytes, we discuss the possible mechanism of solute-solvent interplay that explains the observed anomalies [2]. Elucidation of the molecular dynamics in aqueous electrolytes provides impetus for the future development of energy storage, water treatment, water desalination, and nanofluidic technologies.


References:
[1] Artemov, V. G.; Uykur, E.; Kapralov, P. O.; Kiselev, A.; Ouerdane, H.; Stevenson, K. J.; Maier, J.; Dressel, M. “Anomalously High Protonic Conductivity of Interfacial Water,” J. Phys. Chem. Lett. 2020, 11, 3623-3628.
[2] Artemov, V. G.; Ryzhov, A.; Ouerdane, H.; Stevenson, K. J. “Electrodynamic Difference Between Weak and Strong Electrolytes Admits Solute-solvent Interplay via Proton Exchange Reactions,” J. Phys. Chem. Lett. 2023, 127 (1), 261–268.

Speaker: Keith Stevenson - KJS Consulting
Professor Stevenson received his PhD in 1997 from the University of Utah under the supervision of Professor Henry S. White. Subsequently, he held a postdoctoral appointment at Northwestern University (1997-2000) with Joseph T. Hupp; a professorial appointment from 2000-2015 at the University of Texas at Austin. From 2014-2022, he led the development of a new graduate level research and innovation institute in Moscow, Russia having served as Provost, Full Professor and Founder of the Center for Energy Science and Technology (CEST). Stevenson’s research interests are aimed at elucidating and controlling chemistry at solid/liquid interfaces vital to many emerging energy storage and energy conversion technologies. He has published over 350 peer-reviewed publications, 14 patents, and six book chapters in this field. Recent awards include the SEAC Charles N. Reilley Award (2021), and the Electrochemical Society David C. Grahame Award in Analytical and Physical Electrochemistry (2023).