Research
Sorbents and Alternative Regeneration for Direct Air Capture
Direct air capture (DAC) of CO2 from the atmosphere is a negative emission technology that requires high capacity and high selectivity sorbents. Further, there is a need to make these sorbents regenerable with minimal energy input for their continued use. We develop new sorbents that are amenable for non-conventional approaches where targeted energy transfer via electromagnetic field can be coupled with moisture-swing to reduce the energy requirement of DAC.
Read out most recent perspective article in the Special issue of Future Perspectives on Separation Technologies: Zeeshan et al., Frontiers in Sustainability. (2023)
Lee and Cagli et al., Chemsuschem, 2023 - microwave regeneration and oxidative thermal degradation
Klemm et al., ACS Sustainable Chemistry & Engineering, 2023 - a thorough understanding of CO2 absorption by choline amino acid based sorbents
Ion Solvation and Mobility in Ionic Liquids
ILs are considered nonflammable and they have negligible vapor pressures; thus are safer alternatives over organic solvents for lithium, lithium-ion and sodium-ion batteries where aqueous electrolytes are not suitable. To improve ion conduction in ILs, we must first understand ion solvation and mobility. We employ Raman spectroscopy to study solvate structures in complex IL-IL mixtures and electrochemical techniques to perform ion transference measurements. The outcome of this study is pertinent to high energy density, lithium based battery chemistry with implifications in other applications such as electrodeposition processes.
For more details:
Penley and Wang et al, Journal of Chemical Engineering Data, 2022 - IL electrolytes with asymmetric anion
Penley et al., Frontiers in Energy Research, 2021 - Solvation of Li+ examined by DFT
Huang et al, Journal of Physical Chemistry B, 2018 - Li+ solvation and mobility in IL/IL mixtures
Huang, Lee and Gurkan, Industrial & Engineering Chemistry Research, 2019 - IL/IL electrolytes in batteries
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Electrode-Electrolyte Interfaces
The interfacial structure of ionic liquids (ILs) near electrified surfaces do not follow classical theories such as Helmholtz, Gouy-Chapman and Stern. We investigate these complex interfaces utilizing advanced spectroscopy and scattering techniques, coupled with electrochemical methods. We design and synthesize advanced electrolytes and investigate their interfacial behavior with the developed techniques to better understand the structure-property relations that govern the electrode-electrolyte interfaces and redox reactions at these interfaces.
Read our related papers:
Klein et al, ACS Applied Electronic Materials, 2022 - Neutron Reflectivity of ILs
Shaheen et al, Journal of Electrochemical Society, 2022 - Nitroxy radical oxidation
Dean et al, Journal of Physical Chemistry C, 2022 - H-bonded eutectics at interfaces
Klein et al, Journal of Physical Chemistry C, 2019 - Interface
Klein et al, Physical Chemistry Chemical Physics, 2019 - Potential dependent capacitance of ILs
Xu et al, Journal of Applied Electrochemistry, 2019 - Capacitors with surfactant ILs
Luo et al, ACS Applied Materials & Interfaces, 2018 - Hybrid electrodes for capacitors
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Deep Eutectic Solvents: Understanding Structure and Physical Properties
DES are alternatives to ILs and constitute a hydrogen bond donor and a hydrogen bond acceptor as opposed to discrete ions. Owing to their good solvent strength, achieving high concentrations of redox active species are possible. Therefore, DES are promising for redox flow batteries. Our focus is to understand the liquid structure and physical properties as a function of DES composition. We further characterize the redox activity of functionalized salts in DES.
This project is part of Breakthrough Electrolytes for Energy Storage (BEES): a DOE Energy Frontier Research Center.
Watch the video:
Metal-Free Deep Eutectic Solvents Preparation, Physical Properties, and Significance
Read the perspective paper at the Journal of Physical Chemistry Letters, 2019
Everything you need to know about DESs is in this 2021 Chemical Reviews article.
Want to know why we study these types of electrolytes for redox flow batteries? Read about it in our perspective article in Journal of Electrochemical Society. (2022)
Redox flow battery with DES electrolytes ACS Applied Materials & Interfaces. (2023)
Our collaborative study on the "Evolution of microscopic heterogeneity and dynamics in DESs" available at Nature Communications. (2022)
Importance of the second solvation shell in eutectic solvents for electron transfer reactions: Journal of Chemical Engineering Data, 2022.
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Polymer-ionic liquid Composite Capsules and Membranes for Gas Separations
ILs have high CO2 solubilities and can be easily engineered into composite materials such as capsules as absorbents and thin films as membranes for gas separations. We create new interfaces for gas-liquid reactions and study their applications for CO2 filtration from air.
Read our paper:
Lee et al, Nanoscale, 2022 - Facilitated transport membranes for CO2 separation from air
Lee et al, ACS Sustainable Chemistry & Engineering, 2021 - Solvents for reactive CO2 capture
Lee et al, ACS Applied Materials & Interfaces, 2020 - Capsules of ILs for CO2 capture
Huang et al, Industrial & Engineering Chemistry Research, 2019 - Encapsulating ILs
Read more about it at the following links:
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Electrochemical Reduction of Carbon Dioxide
The electrochemical reduction of carbon dioxide is the 146-year-old, still an unresolved, challenge that was first studied in 1870 by M. E. Royer in Paris. It was considered that the only significant products in aqueous solutions were formic acid (HCOOH) and formates (HCOO-) of alkali metals with the highest current densities (> 90 %) achievable with mercury or amalgam (alloys of mercury and metals) electrodes. Despite the progress thereafter, the process still requires to be optimized for selectivity and efficiency. We study the role of ILs in electroreduction of CO2 in order to reduce the energy requirement for the process.
Dongare et al., ACS Catalysis, 2023 - CO2 reduction co-catalyzed by functional IL