M. R. Hassan, B. A. Colon, J. Russell, T. R. Calhoun, "Small Molecule Sorting: A Fluorescence Study of Microemulsions," J. Phys. Chem. B, 2022.
S. T. Hamilton, T. G. Feric, A. Gladysiak, N. M. Cantillo, T. A. Zawodzinski, A. A. Park, "Mechanistic Study of Controlled Zinc Electrodeposition Behaviors Facilitated by Nanoscale Electrolyte Additives at the Electrode Interface," ACS Applied Materials & Interfaces, 2022.
A. E. Imel, B. Barth, D. G. Hayes, M. Dadmun, T. Zawodzinski, "Microemulsions as Emerging Electrolytes: The Correlation of Structure to Electrochemical Response," ACS Applied Materials & Interfaces, 2022.
N. Shaheen, W. Dean, J. Rintamaki, M. B. Vukmirovic, B. E. Gurkan, R. Akolkar, "Electro-oxidation of nitroxide radicals: Adsorption-mediated charge transfer probed using SERS and potentiometry," Journal of the Electrochemical Society, 2022.
J. M. Klein, H. W. Wang, R. L. Sacci, J. F. Browning, B. Gurkan, "Smooth Modified Surfaces of Silicon for the Study of Ionic Liquid Interfaces by Neutron Reflectometry", ACS Applied Electronic Materials, 2022.
S. T. Hamilton, T. G. Feric, S. Bhattacharyya, N. M. Cantillo, S. G. Greenbaum, T. A. Zawodzinski, A. Park, "Nanoscale Hybrid Electrolytes with Viscosity Controlled Using Ionic Stimulus for Electrochemical Energy Conversion and Storage", JACS Au, 2022.
Raziyeh Ghahremani, Robert F. Savinell and Burcu Gurkan, "Hydrogen Bonded Concentrated Electrolytes for Redox Flow Batteries: Limitations and Prospects", Journal of The Electrochemical Society, 2022.
C. C. Fraenza and S. G. Greenbaum, "Broadband NMR relaxometry of electrolytes for energy storage", Chemical Physics Reviews, 2022.
Y. Zhang, H. Squire, B. Gurkan, and E. J. Maginn, "Refined Classical Force Field for Choline Chloride and Ethylene Glycol Mixtures over Wide Composition Range", Journal of Chemical & Engineering Data, 2022.
Studies carried out by BEES and other researchers realized recently that what was believed to be the deep eutectic mixture sometimes is not. For example, it has been accepted that the 1:2 molar ratio of choline chloride (ChCl) and ethylene glycol (EG) is the eutectic point. However, new studies revealed that the eutectic mixture forms at the 1:4 ratio. On the other hand, there is no guarantee that a mixture at the eutectic point has the best properties for optimum electrochemical performance in battery applications. These discoveries clearly demonstrated the urgent need for systematic studies of eutectic solvent mixtures over a wide composition range. Unfortunately, reliable force field for such study is not available. In the current work, the widely used general Amber force field (GAFF) was refined for ChCl and EG mixtures by scaling the atomic partial charges and vdW parameters to fit experimental density and viscosity at multiple compositions. The performance of the refined force field is significantly improved compared to the original model and the calculated density, viscosity, self-diffusion coefficient, and ionic conductivity agree with experiments quantitatively even beyond the fitting compositions and temperatures. This makes it possible to systematically study the liquid properties of the ChCl and EG mixtures as a function of ChCl fraction over a wide composition range. In addition, the procedure used in the current work to refine the ChCl and EG force field can be easily applied to other eutectic liquid mixture systems.
Using the new model, the ionic conductivity of the ChCl and EG mixtures as a function of ChCl mole fraction was studied. It was found that the dynamics in these mixtures with ChCl mole fraction equal to or greater than 20% are similar to that of ionic liquids, high temperature molten salts, and highly concentrated water-in-salt electrolytes. These findings provide new insights of the ion conduction mechanism in these mixtures.
S. Spittle, D. Poe, B. Doherty, C. Kolodziej, L. Heroux, M. A. Haque, H. Squire, T. Cosby, Y. Zhang, C. Fraenza, S. Bhattacharyya, M. Tyagi, J. Peng, R. A. Elgammal, T. Zawodzinski, M. Tuckerman, S. Greenbaum, B. Gurkan, M. Dadmun, E. J. Maginn, and J. Sangoro, "Evolution of Microscopic Heterogeneity and Dynamics in Choline Chloride-based Deep Eutectic Solvents", Nature Communications, 13, 219, 2022.
C. C. Fraenza, R. A. Elgammal, M. N. Garaga, S. Bhattacharyya, T. A. Zawodzinski, and S. G. Greenbaum, "Dynamics of Glyceline and Interactions of Constituents: A Multi-technique NMR study", The Journal of Physical Chemistry B, 126, 4, 890-905, 2022.
The dynamics of the organic components of the deep eutectic solvent glyceline were analyzed using an array of complementary nuclear magnetic resonance (NMR) methods. The results showed that the translational and rotational motions of all species become faster with increasing ChCl concentration up to the eutectic point (33mol% ChCl). This suggests that the glycerol H- bonding network is disrupted as choline is added, but primarily in regions where there is intimate mixing of the two components. Thus, the local dynamics of most of the glycerol resembles that of pure glycerol until substantial choline chloride is present. Moreover, a relatively slow hydroxyl H-exchange process between glycerol and choline protons was deduced from the data.
A. E. Imel, B. Barth, D. G. Hayes, M. Dadmun, T. Zawodzinski, "Microemulsions as Emerging Electrolytes: The Correlation of Structure to Electrochemical Response", ACS Applied Materials & Interfaces, 2022.
B. Barth, A. Imel, K. M. Nelms, G. A. Goenaga, T. Zawodzinski, "Microemulsions: Breakthrough Electrolytes for Redox Flow Batteries", Frontiers in Chemistry, 2021.
Matthew A. Harris, Thomas Kinsey, Durgesh V. Wagle, Gary A. Baker and Joshua Sangoro, "Evidence of a liquid–liquid transition in a glass-forming ionic liquid", PNAS, 2021.
J. Peng, Y. Xiao, A. Imel; B. Barth, N. Cantillo, K. M.Nelms, T. A. Zawodzinski, "Electrolyte effects on the electrochemical performance of microemulsions", Electrochimica Acta, 2021.
S. Overa, T. G. Feric, A. Park, F. Jiao, "Tandem and Hybrid Processes for Carbon Dioxide Utilization", Joule, 2021.
T. G. Feric, S. T. Hamilton, and A. Park, "Insights into the Enhanced Oxidative Thermal Stability of Nanoparticle Organic Hybrid Materials Developed for Carbon Capture and Energy Storage", Energy & Fuels, 2021.
Xiaochen Shen, Nicholas Sinclair, Jesse Wainright, Adam Imel, Brian Barth, Thomas Zawodzinski and Robert F. Savinell, "A Study of Ferrocene Diffusion in Toluene/Tween 20/1-Butanol/Water Microemulsions for Redox Flow Battery Applications", Journal of The Electrochemical Society, 2021.
X. Shen, N. Sinclair, J. Wainright and R. F. Savinell, "Methods? Analyzing Electrochemical Kinetic Parameters in Deep Eutectic Solvents Using an Extended Butler-Volmer Equation", Journal of The Electrochemical Society, 2021.
Ibrahim Alfurayj, Carla Cecilia Fraenza, Yong Zhang, Rathiesh Pandian, Stephanie Spittle, Bryce Hansen, William Dean, Burcu Gurkan, Robert Savinell, Steve Greenbaum, Edward Maginn, Joshua Sangoro, and Clemens Burda, "Solvation Dynamics of Wet Ethaline: Water is the Magic Component", The Journal of Physical Chemistry B, 125, 31, 8888-8901, 2021.
Jing Peng, Nelly M. Cantillo, Ye Xiao, K. McKensie Nelms, Lacey S. Roberts, Gabriel Goenaga, Adam Imel, Brian Andrew Barth, Mark Dadmun, Douglas G. Hayes and Thomas Zawodzinski, "Decoupling Conductivity and Solubility in Electrolytes Using Microemulsions", Journal of The Electrochemical Society, 2021.
Nicholas S. Sinclair, Xiaochen Shen, Evan Guarr, Robert F. Savinell and Jesse S. Wainright, "Electrochemical Decomposition of Primary Alcohol Groups in Deep Eutectic Solvents", Journal of The Electrochemical Society, 2021.
Tony G. Feric, Sara T. Hamilton, Nelly M. Cantillo, Adam E. Imel, Thomas A. Zawodzinski, and Ah-Hyung Alissa Park, "Dynamic Mixing Behaviors of Ionically Tethered Polymer Canopy of Nanoscale Hybrid Materials in Fluids of Varying Physical and Chemical Properties", The Journal of Physical Chemistry B, 2021.
Mounesha N. Garaga, Nishani Jayakody, Carla C. Fraenza, Boris Itin, Steven Greenbaum, "Molecular-level insights into structure and dynamics in ionic liquids and polymer gel electrolytes", Journal of Molecular Liquids, 2021.
Guanhe Rim, Noyonika Roy, Diandian Zhao, Shiho Kawashima, Phillip E. Stallworth, Steve G. Greenbaum and Ah-Hyung Alissa Park , "CO2 Utilization in Built Environment via the PCO2 Swing Carbonation of Alkaline Solid Wastes with Different Mineralogy", Faraday Discussions, 2021.
Md Ashraful Haque, Tony G. Feric, Sara T. Hamilton, Ah-Hyung Alissa Park, Mark D. Dadmun, "Structure and Dispersion of Free and Grafted Polymer in Nanoparticle Organic Hybrid Materials-based Solutions by Small Angle Neutron Scattering", The Journal of Physical Chemistry C, 2021.
Emmanuel Urandu Mapesa, Nelly M. Cantillo, Sara Triana Hamilton, Matthew A. Harris, Thomas A. Zawodzinski Jr., Ah-Hyung Alissa Park, Joshua Sangoro, "Localized and Collective Dynamics in liquid-like Polyethylenimine-based Nanoparticle Organic-Inorganic Hybrid Materials", Macromolecules, 2021.
Nicholas S. Sinclair, Derrick Poe, Robert F. Savinell, Edward J. Maginn, Jesse S. Wainright, "A Nitroxide Containing Organic Molecule in a Deep Eutectic Solvent for Flow Battery Applications ", J. Electrochem. Soc., 168, 020527, 2021.
The nitroxide radical redox organic molecule, 2-phenyl-4,4,5,5-tetrame- thylimidazoline-1-oxyl-3-oxide (PTIO), was investigated for the first time in a deep eutectic solvent (DES)-like system consisting of a 1:4 molar ratio of choline chloride and ethylene glycol (Ch1EG4) as a redox flow battery electrolyte. PTIO is an attractive redox organic as it is a single molecule with three oxidation states, and can provide both positive and negative redox couples for a flow battery. A flow battery using the PTIO/Ch1EG4 electrolyte demonstrated nearly 50% round trip efficiency with an approximately 1 V open circuit potential. Inefficiencies were primarily due to membrane resistance which can be significantly lowered with increased temperature. While PTIO appears stable over short periods (hours), the oxidized form is not stable in the DES-like electrolyte over longer times. Molecular modeling was performed to investigate the relative stability of PTIO in DES as compared to the previously studied 4-hydroxy-TEMPO (4HT). It was found that the oxoammonium cation 4HT+ exhibits a noticeably larger nucleophilic reactive cloud as compared to PTIO+, indicating a higher reactivity. This method to predict stability of the oxoammonium cation shows promise to inform the design and synthesis of promising redox systems based on nitroxide radicals in DES electrolytes to identify new chemistries for large scale energy storage.
William Dean, Jeffrey Klein and Burcu Gurkan, "Do Deep Eutectic Solvents Behave Like Ionic Liquid Electrolytes? A Perspective from the Electrode-Electrolyte Interface2" Journal of The Electrochemical Society, 168, 026503, 2021.
This study discusses the electrical double layer of choline chloride and ethylene glycol based mixtures (1:2, 1:4, 1:6 molar ratios) including the deep eutectic solvent (DES) ethaline as well as glyceline (1:2 choline chloride:glycerol). Based on the electrochemical impedance spectroscopy (EIS) performed both on gold, platinum and glassy carbon surfaces, the electrode-electrolyte interfaces of DESs is found to be best described by a modified Gouy-Chapman model where only a diffuse layer is assumed with an ion-interaction parameter. The large ion size and the existing H-bonding network in these mixtures prevents the rapid rise in capacitance typical of the classical Gouy-Chapman model, resulting in a shallower U-shaped differential capacitance. This behavior is quite different than ionic liquids (ILs) which are extremely concentrated electrolytes with no neutral solvent molecules. Furthermore, the capacitive behavior of Cl-based DESs present specific ion adsorption on metal surfaces, specifically on gold, Au-Cl complexes form. This work represents one of the earliest srtudies in the field in regards to the theory development for the electrical double layer in DESs which is pertinent to electrochemical kinetics, morphology in electrodeposition processes as well as energy storage.
PRESENTATION: N. Shaheen, W. Dean, D. Penley, J. Rintamaki, M. Vukmirovic, B. Gurkan, R. Akolkar, "Spectroscopic and Electrochemical Investigation of Adsorbed Nitroxide Radicals", Presented on the 240th ECS Meeting, October 10-14, 2021.
B. E. Gurkan, E. J. Maginn, and E. B. Pentzer, "Deep Eutectic Solvents: A New Class of Versatile Liquids", The Journal of Physical Chemistry B, 2020.
Yun-Yang Lee, Drace Penley, Aidan Klemm, William Dean, and Burcu Gurkan, "Deep Eutectic Solvent Formed by Imidazolium Cyanopyrrolide and Ethylene Glycol for Reactive CO 2 Separations" ACS Sustainable Chemistry Engineering, 2020.
Hansen, B. B.; Spittle, S.; Chen, B.; Poe, D.; Zhang, Y.; Klein, J. M.; Horton, A.; Adhikari, L.; Zelovich, T.; Doherty, B. W.; Gurkan, B.; Maginn, E. J.; Ragauskas, A.; Dadmun, M.; Zawodzinski, T. A.; Baker, G. A.; Tuckerman, M. E.; Savinell, R. F.; Sangoro, J. R., "Deep Eutectic Solvents: A Review of Fundamentals and Applications", Chemical Review, 121, 3, 1232-1285, 2020.
Nora A. Shaheen,Mahesh Ijjada, Miomir B. Vukmirovic, and Rohan Akolkar, "Mechanism of Electrochemical Oxidation of Nitroxide Radicals in Ethaline Deep Eutectic Solvent" J. Electrochem. Soc., 167, 143505, 2020.
In this manuscript, an “Adsorption – Desorption” mechanism is proposed to explain unusual values of the anodic charge transfer coefficient associated with the electrochemical oxidation of two nitroxide-containing organics: TEMPO and 4-hydroxy-TEMPO. These values were extracted in both aqueous and deep eutectic solvent electrolytes, and were found to approach unity under a variety of conditions. In this mechanism, the nitroxide radical undergoes (step i) fast adsorption and charge transfer, followed by (step ii) slow desorption of the oxidized product. This impact of this desorption-limited oxidation was further investigated on transient cyclic voltammograms. Through a numerical model, the irreversibility observed at high concentrations was captured. Understanding mechanisms governing charge transfer of redox-active organics is critical for designing high energy density organic flow batteries, particularly when limited by surface coverage of the redox-active organic.
Jing Peng, Nelly M. Cantillo, K. McKensie Nelms, Lacey S. Roberts, Gabriel Goenaga, Adam Imel, Brian Andrew Barth, Mark Dadmun, Luke Heroux, Douglas G. Hayes, and Thomas Zawodzinski, "Electron Transfer in Microemulsion-Based Electrolytes" ACS Applied Materials and Interfaces, 2020.
Nelly M. Cantillo, Maria Bruce, Sara T. Hamilton, Tony G. Feric, Ah-Hyung Alissa Park and Thomas A. Zawodzinski Jr., "Electrochemical Behavior of Copper Ion Complexed with Nanoparticle Organic Hybrid Materials" IOP Science, 2020.
Nishani K Jayakody, Carla C. Fraenza, Steven G. Greenbaum, David S. Ashby, and Bruce S. Dunn, "NMR Relaxometry and Diffusometry Analysis of Dynamics in Ionic Liquids and Ionogels for Use in Lithium Ion Batteries" Journal of Physical Chemistry B, 2020.
Brian Chen, Sarah Mitchell, Nicholas Sinclair, Jesse Wainright, Emily Pentzer and Burcu Gurkan, "Feasibility of TEMPO-functionalized imidazolium, ammonium and pyridinium salts as redox-active carriers in ethaline deep eutectic solvent for energy storage", Molecular Systems Design and Engineering, 2020.
TEMPO is a common redox active specie that is studied widely in redox flow batteries. However, we found that its solubility is limited in deep eutectic solvent ethaline. This study derivatized imidazolium, ammonium, and pyridinium salts with the nitroxy radical functionality to incorporate into ethaline. While the functionalization of the salts improved the solubility of TEMPO, its reactivity in the presence of the alcohol group of ethylene glycol led to redox irreversibility. The redox flow battery experiments demonstrate the feasibility of these salts as redox active species in deep eutectic solvents for energy storage.
Jeffrey M. Klein, Henry Squire, William Dean, and Burcu E. Gurkan, "From Salt in Solution to Solely Ions – Solvation of MethylViologen in Deep Eutectic Solvents and Ionic Liquids", Journal of Physical Chemistry B, 2020.
Solvation of redox species in hydrogen bonded concentrated electrolytes such as deep eutectic solvents (DESs) is important to understand as it impacts redox potentials and redox reversibility in energy storage. Raman spectroscopy suggests that the redox specie methyl viologen dichloride (MVCl2) is strongly solvated by ethylene glycol in choline bis(trifluorosulfonyl)imide (TFSI) and ethylene glycol mixtures whereas it is interstitially accommodated in holes of ethaline (choline chloride : ethylene glycol, 1:2) mixtures and the pyrrolidinium TFSI ionic liquid. The unhindered redox center of MVCl2 in DES ethaline leads to its robust redox reversibility.
Yong Zhang, Derrick Poe, Luke Heroux, Henry Squire, Brian W. Doherty, Zhuoran Long,Mark Dadmun, Burcu Gurkan, Mark E. Tuckerman, and Edward J. Maginn, "Liquid Structure and Transport Properties of the Deep EutecticSolvent Ethaline", Journal of Physical Chemistry B, 124, 5251-5264, 2020.
Ethaline, comprised of a 1:2 molar ratio of choline chloride (ChCl) and ethylene glycol (EG), is one of the most widely studied deep eutectic solvents (DES). This work reported a comprehensive study of the structure and dynamics of ethaline using a range of experimental and simulation techniques. Experimentally measured densities and viscosities match previously reported values very well. Classical and ab initio molecular dynamics simulations both capture experimental liquid structure, as determined by neutron scattering measurements. Computed diffusivities and viscosities also agree well with experiments. The simulations suggest that the solvation environment in ethaline is more complicated than what may be assumed based on its stoichiometric composition. Addition of ChCl into pure EG breaks the hydrogen bond (HB) network in EG and multiple types of HBs are formed. In particular, the HBs between Cl and EG hydroxyl groups were found to be stronger than those hydroxyl HBs in pure EG, resulting in higher viscosity and slower dynamics in ethaline compared to pure EG. The complex HBs in ethaline also cause complexity in dynamics. Rotational relaxation of choline is much slower than ethylene glycol. Dynamic heterogeneities persist for over 10 ns in ethaline, with the chloride ion experiencing the most dynamical heterogeneity due to its hydrogen bonding interactions. Based on MD simulations, significant insights into coordination probability, contact pair fraction, and hydrogen bond dynamics, were obtained. These analyses provided great insight into the structure and dynamics of ethaline and revealed the direct connection between local hydrogen bonding structure and transport properties. These fundamental understandings will guide the study and design of other DES mixtures, and the development of electrolytes with optimum properties for flow battery applications.
Miomir B. Vukmirovic, Radoslav R. Adzic, and Rohan Akolkar, "Copper Electrodeposition from Deep Eutectic Solvents – Voltammetric Studies Providing Insights into the Role of Substrate: Platinum vs. Glassy Carbon", Journal of Physical Chemistry B, 2020.
X. Shen, N. Sinclair, J. Wainright, R. Akolkar, and R.F. Savinell, "Evaluating and developing a reliable reference electrode for choline chloride based deep eutectic solvents", Journal of the Electrochemical Society, 2020 167 (8).
Guanhe Rim, Ariane Katrina Marchese, Phillip Stallworth, Steven G. Greenbaum, Ah-Hyung Alissa Park, "29 Si Solid State MAS NMR Study on Leaching Behaviors and Chemical Stability of Different Mg-Silicate Structures CO2 Sequestration", Chemical Engineering Journal, 396 (c).
L. Chang and A. J. Bard, "Electrochemical Characterization of Bromine Reduction to Tribromide in Individual Nitrobenzene-in-Water Emulsion Droplets", Journal of The Electrochemical Society, 2020 167 (6).
Nora A. Shaheen, Ijjada Mahesh, Miomir B. Vukmirovic, Rohan Akolkar, "Hysteresis effects and roughness suppression efficacy of polyethylenimine additive in Cu electrodeposition in ethaline", Electrochemistry Communications 2020 115 106721
PRESENTATION: M. Ijjada, N. Shaheen, M. Vukmirovic, R. Akolkar, "Mechanism Underlying Electron-Transfer Reactions Involving TEMPO and 4-Hydroxy-TEMPO in Deep Eutectic Solvents", Presented on the ECS PRIME 2020, October 4-9, 2020.
J.M. Klein; H. Squire; B. Gurkan, "Electroanalytical Investigation of the Electrode–Electrolyte Interface of Quaternary Ammonium Ionic Liquids: Impact of Alkyl Chain Length and Ether Functionality, The Journal of Physical Chemistry C, 124, 10, 5613-5623, (2019).
This study developed a combined surface enhanced Raman spectroscopy (SERS) and electrochemical impedance spectroscopy (EIS) method to probe electrode-electrolyte interfaces to identify the surface species of ionic liquids (ILs) as the electrode potential is swept. This method can be applied more broadly to other complex electrolytes. The study shows that long alkyl chains of IL cations buckle to compact with increased polarization (a phenomenon that has not been reported before).
Dai Shen, Miomir B Vukmirovic, Rohan Akolkar, "Understanding the Role of Complexation in the Charge-Transfer Kinetics of the Cu2+ + e ↔ Cu1+ Redox Reaction in Ethaline Deep Eutectic Solvent", Journal of The Electrochemical Society, 166 (15), E526-E532 (2019)
Burcu Gurkan, Henry Squire, and Emily Pentzer, "Metal-Free Deep Eutectic Solvents: Preparation, Physical Properties, and Significance", The Journal of Physical Chemistry Letters 2019 10 (24), 7956-7964 (2019)
This perspective provides an overview of metal-free deep eutectic solvents (DESs) with the goal of standardizing sample preparation and characterization in the field. Specific properties of interest for various applications including energy storage and characterization methods are summarized for the newcomers to the field in order to engage other researchers and help advance the field.
Dai Shen, Katherine Steinberg, Rohan Akolkar, “Avoiding Pitfalls in the Determination of Reliable Electrochemical Kinetics Parameters for the Cu2+→Cu1+ Reduction Reaction in Deep Eutectic Solvents”, Journal of The Electrochemical Society , 165 (14), E808-E815, 2018,