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Zhang S, Jiang DE, Zhou N, Tang J, Zhang K, Li Y, Hu J, Peng C, Liu H, Yang B, Yao Y. Ionic liquids intercalation in titanium carbide MXenes: A first-principles investigation. J Comput Chem 2024; 45:2294-2307. [PMID: 38847556 DOI: 10.1002/jcc.27444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/24/2024] [Accepted: 05/23/2024] [Indexed: 08/15/2024]
Abstract
Herein, we present a density functional theory with dispersion correction (DFT-D) calculations that focus on the intercalation of ionic liquids (ILs) electrolytes into the two-dimensional (2D) Ti3C2Tx MXenes. These ILs include the cation 1-ethyl-3-methylimidazolium (Emim+), accompanied by three distinct anions: bis(trifluoromethylsulfonyl)imide (TFSA-), (fluorosulfonyl)imide (FSA-) and fluorosulfonyl(trifluoromethanesulfonyl)imide (FTFSA-). By altering the surface termination elements, we explore the intricate geometries of IL intercalation in neutral, negative, and positive pore systems. Accurate estimation of charge transfer is achieved through five population analysis models, such as Hirshfeld, Hirshfeld-I, DDEC6 (density derived electrostatic and chemical), Bader, and VDD (voronoi deformation density) charges. In this work, we recommend the DDEC6 and Hirshfeld-I charge models, as they offer moderate values and exhibit reasonable trends. The investigation, aimed at visualizing non-covalent interactions, elucidates the role of cation-MXene and anion-MXene interactions in governing the intercalation phenomenon of ionic liquids within MXenes. The magnitude of this role depends on two factors: the specific arrangement of the cation, and the nature of the anionic species involved in the process.
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Affiliation(s)
- Shaoze Zhang
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - De-En Jiang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Nan Zhou
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Jiaxing Tang
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Keyu Zhang
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Yin Li
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Junxian Hu
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Changjun Peng
- Key Laboratory for Advanced Materials and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Honglai Liu
- Key Laboratory for Advanced Materials and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Bin Yang
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
| | - Yaochun Yao
- National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, China
- Engineering Laboratory for Advanced Battery and Materials of Yunnan Province, Kunming University of Science and Technology, Kunming, China
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Tu YJ, Peng ST. Influence of surface nanostructure-induced innermost ion structuring on capacitance of carbon/ionic liquid double layers. Phys Chem Chem Phys 2024; 26:5932-5946. [PMID: 38299635 DOI: 10.1039/d3cp05617a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
Ionic liquids have drawn great interest as electrolytes for energy storage applications in which they form characteristic electrical double layers at electrode interfaces. For ionic liquids at carbon electrode interfaces, their double layers are subject to nanoscale structuring of the electrode surface, involving altered ion structure and interactions that significantly influence the double layer capacitance. In this regard, we investigate the modulation of ionic liquid double layers by electrode surface roughness and the resulting effects on the ion structure, interaction, and capacitance. We performed fixed voltage molecular dynamics simulations to compute the differential capacitance profiles for the ionic liquids [BMIm+][TFSI-] and [BMIm+][FSI-] at model carbon electrode interfaces with the surface channel width at subnanometer and nanometer scales. We find that both [BMIm+][TFSI-] and [BMIm+][FSI-] exhibit enhanced differential capacitance for the electrode surface with a subnanometer channel width relative to the flat graphene surface, but the most pronounced enhancements for these two ionic liquids unexpectedly appear at different applied potential regimes. For [BMIm+][TFSI-], the nanostructured electrode shows significant enhancement of capacitance at high positive potential. For [BMIm+][FSI-], on the other hand, this enhancement is small at positive polarization but noticeable at low negative potential. We demonstrate that differences in these capacitance trends is due to differences in ion correlation that arise from a steric constraint of nanostructured electrode surface on the voltage-mediated restructuring of ions closest to the electrode interface. For example, the TFSI- and FSI- anions tend to structure with their charged and nonpolar groups in contact with the positive electrode surface when the constraint on these close-contact anions is relaxed. This anion structuring largely retains the cation association near the nanostructured electrode, resulting in only a slight increase in capacitance at positive polarization. Our simulations highlight the sensitive dependence of the innermost ion structure on the electrode surface nanostructure and applied voltage and the resulting influence on ion correlation and capacitance of ionic liquid double layers.
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Affiliation(s)
- Yi-Jung Tu
- Department of Applied Chemistry, National Chi Nan University, Puli, Nantou, 54561, Taiwan.
| | - Sheng-Ting Peng
- Department of Applied Chemistry, National Chi Nan University, Puli, Nantou, 54561, Taiwan.
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Stephens NM, Smith EA. Structure of Deep Eutectic Solvents (DESs): What We Know, What We Want to Know, and Why We Need to Know It. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14017-14024. [PMID: 36346803 DOI: 10.1021/acs.langmuir.2c02116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Deep eutectic solvents (DESs) are a tunable class of solvents with many advantageous properties including good thermal stability, facile synthesis, low vapor pressure, and low-to-negligible toxicity. DESs are composed of hydrogen bond donors and acceptors that, when combined, significantly decrease the freezing point of the resulting solvent. DESs have distinct interfacial and bulk structural heterogeneity compared to traditional solvents, in part due to various intramolecular and intermolecular interactions. Many of the physiochemical properties observed for DESs are influenced by structure. However, our understanding of the interfacial and bulk structure of DESs is incomplete. To fully exploit these solvents in a range of applications including catalysis, separations, and electrochemistry, a better understanding of DES structure must be obtained. In this Perspective, we provide an overview of the current knowledge of the interfacial and bulk structure of DESs and suggest future research directions to improve our understanding of this important information.
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Affiliation(s)
- Nicole M Stephens
- Ames National Laboratory, U.S. Department of Energy, Ames, Iowa 50011-3111, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
| | - Emily A Smith
- Ames National Laboratory, U.S. Department of Energy, Ames, Iowa 50011-3111, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
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