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Haque MA, Hamilton ST, Feric TG, Park AHA, Dadmun MD. Elucidating the assembly of nanoparticle organic hybrid materials (NOHMs) near an electrode interface with varying potential using neutron reflectivity. NANOSCALE 2024; 16:8521-8532. [PMID: 38592848 DOI: 10.1039/d3nr06621e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
A critical concern regarding electrolyte formulation in an electrochemical environment is the impact of the interaction of the multiple components (i.e., supporting electrolyte or additive) with the electrode surface. Recently, liquid-like neat Nanoparticle Organic Hybrid Materials (NOHMs) have been considered as an electrolyte component to improve the transport of redox-active species to the electrode surface. However, the structure and assembly of the NOHMs near the electrode surface is unknown and could significantly impact the electrode-electrolyte interface. Hence, we have investigated the depth profile of polyetheramine (HPE) polymer and NOHM-I-HPE (nanoparticles with ionically bonded HPE polymer) in deuterated water (D2O) in the presence of two different salts (KHCO3 and ZnCl2) near two different electrode surfaces using neutron reflectometry. Moreover, the depth profile of the NOHM-I-HPE near the electrode surface in a potential has also been studied with in situ reflectivity experiments. Our results indicate that a change in the chemical structure/hydrophilicity of the electrode surface does not significantly impact the ordering of HPE polymer or NOHM-I-HPE near the surface. This study also indicates that the NOHM-I-HPE particles form a clear layer near the electrode surface immediately above an adsorbed layer of free polymer on the electrode surface. The addition of salt does not impact the layering of NOHM-I-HPE, though it does alter the conformation of the polymer grafted to the nanoparticle surface and free polymer sequestered near the surface. Finally, the application of negative potential results in an increased amount of free polymer near the electrode surface. Correlating the depth profile of free polymer and NOHM-I-HPE particles with the electrochemical performance indicates that this assembly of free polymer near the electrode surface in NOHM-I-HPE solutions contributes to the higher current density of the system. Therefore, this holistic study offers insight into the importance of the assembly of NOHM-I-HPE electrolyte and free polymer near the electrode surface in an electrochemical milieu on its performance.
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Affiliation(s)
- Md Ashraful Haque
- Department of Chemistry, The University of Tennessee, Knoxville, TN, 37996, USA.
| | - Sara T Hamilton
- Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
- Lenfest Center for Sustainable Energy, The Earth Institute, Columbia University, USA
| | - Tony G Feric
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
- Lenfest Center for Sustainable Energy, The Earth Institute, Columbia University, USA
| | - Ah-Hyung Alissa Park
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
- Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
- Lenfest Center for Sustainable Energy, The Earth Institute, Columbia University, USA
| | - Mark D Dadmun
- Department of Chemistry, The University of Tennessee, Knoxville, TN, 37996, USA.
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Hayes DG, Barth BA, Pingali SV. Effect of equilibration time on the structural gradient in the vertical direction for bicontinuous microemulsions in Winsor-III and -IV systems. SOFT MATTER 2024. [PMID: 38651769 DOI: 10.1039/d3sm01741a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Bicontinuous microemulsions (BMEs), self-assembly systems consisting of oil and water nanodomains separated by surfactant monolayers, have many applications. However, changes in structure and properties of BMEs in the vertical direction can affect BMEs' utility. This study's objective was to determine the effect of equilibration time (τeq) on structural changes in the vertical direction for bicontinuous phases of Winsor-III (WIII) systems in situ or after being isolated, for D2O + H2O/1-dodecane/sodium dodecyl sulfate (SDS)/1-pentanol/NaCl at 22 °C. Small-angle neutron scattering (SANS) measurements were performed using a vertical stage sample environment that precisely aligned samples in the neutron beam. SANS data were fitted by the Teubner-Strey (TS) model and changes in TS-derived parameter values were observed. For 10 min ≤ τeq ≤ 4 h, the effective activity of the bicontinuous phase's surfactant monolayers increased with time at all vertical positions. At short equilibration (τeq = 10 min), small but significant amounts of water and oil were transiently emulsified near the WIII upper liquid-liquid interface. WIII systems underwent a relaxation process after being transferred to narrow 1 mm pathlength cells, resulting in a decrease of surfactant activity for the top half of the bicontinuous phase. For isolated bicontinuous phases, results suggest that SDS was desorbed from the BMEs by quartz near the bottom, while near the top, the water concentration near was relatively high. The results suggest that WIII systems should equilibrate for at least 4 hours after being prepared and transferred to a container that differs in cross sectional area and surfactant behavior in BMEs can change near interfaces.
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Affiliation(s)
- Douglas G Hayes
- Department of Biosystems Engineering and Soil Science, University of Tennessee, 2506 E.J. Chapman Drive, Knoxville, TN 37996-4531, USA.
| | - Brian A Barth
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr, Knoxville, TN 37996, USA.
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Pérez Ramos Á, Zheng Y, Peng J, Ridruejo Á. Structure, Partitioning, and Transport behavior of Microemulsion Electrolytes: Molecular Dynamics and Electrochemical Study. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
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Nakao K, Noda K, Hashimoto H, Nakagawa M, Nishimi T, Ohira A, Sato Y, Kato D, Kamata T, Niwa O, Kunitake M. Electrochemistry in bicontinuous microemulsions derived from two immiscible electrolyte solutions for a membrane-free redox flow battery. J Colloid Interface Sci 2023; 641:348-358. [PMID: 36940591 DOI: 10.1016/j.jcis.2023.03.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 03/04/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023]
Abstract
HYPOTHESES Bicontinuous microemulsions (BMEs) have attracted attention as unique heterogeneous mixture for electrochemistry. An interface between two immiscible electrolyte solutions (ITIES) is an electrochemical system that straddles the interface between a saline and an organic solvent with a lipophilic electrolyte. Although most BMEs have been reported with nonpolar oils, such as toluene and fatty acids, it should be possible to construct a sponge-like three-dimensionally expanded ITIES comprising a BME phase. EXPERIMENTS Dichloromethane (DCM)-water microemulsions stabilized by a surfactant were investigated in terms of the concentrations of co-surfactants and hydrophilic/lipophilic salts. A Winsor III microemulsion three-layer system, consisting of an upper saline phase, a middle BME phase, and a lower DCM phase, was prepared, and electrochemistry was conducted in each phase. FINDINGS We found the conditions for ITIES-BME phases. Regardless of where the three electrodes were placed in the macroscopically heterogeneous three-layer system, electrochemistry was possible, as in a homogeneous electrolyte solution. This indicates that the anodic and cathodic reactions can be divided into two immiscible solution phases. A redox flow battery comprising a three-layer system with a BME as the middle phase was demonstrated, paving the way for applications such as electrolysis synthesis and secondary batteries.
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Affiliation(s)
- Kodai Nakao
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan; Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Koji Noda
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Hinako Hashimoto
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Mayuki Nakagawa
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Taisei Nishimi
- Japan Technological Research Association of Artificial Photosynthetic Chemical Process (ARPChem), Room 422, Bldg. 12, Faculty of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akihiro Ohira
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Yukari Sato
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Dai Kato
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Tomoyuki Kamata
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Osamu Niwa
- Advanced Science Research Laboratory, Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama 369-0293, Japan
| | - Masashi Kunitake
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan; Institute of Industrial Nanomaterials, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan.
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Hassan MR, Colon BA, Russell J, Calhoun TR. Small Molecule Sorting: A Fluorescence Study of Microemulsions. J Phys Chem B 2022; 126:4990-4998. [PMID: 35759793 DOI: 10.1021/acs.jpcb.2c02774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The application of microemulsions to a wide range of industries relies on their ability to solubilize small molecules with vastly different structures. Herein, we use multiple fluorescence techniques to probe ionic (rhodamine 6g, r6g), polar (coumarin 153, c153), nonpolar (diphenylanthracene, DPA), and amphiphilic (laurdan) small molecules in a nonionic, bicontinuous microemulsion of varying hydration. All fluorophores investigated were found to associate with the surfactant region despite their different structures and properties. The hydration of the surfactant layer was found to increase linearly with water addition, but while this initially increases the fluidity of the surfactant layer, fluorescence anisotropy of c153 and r6g indicates a stiffening of the surfactant at water content >60%. This stiffening of the surfactant layer at higher water content correlates with a morphological change in the microemulsion from a bicontinuous structure to droplets. In contrast, the nonpolar DPA shows a change in partitioning as hydration changes, increasing its association with the oil domain. Overall, these studies elucidate not only the capability of these microemulsions to host a range of small molecules in the surfactant layer with tunable position but also the ability to probe the driving force of bulk structural changes in these heterogeneous fluids.
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Affiliation(s)
- Muhammad Redwan Hassan
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Brandon A Colon
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - James Russell
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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