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Khan GR, Daschakraborty S. Enhanced fluidity of water in superhydrophobic nanotubes: estimating viscosity using jump-corrected confined Stokes-Einstein approach. Phys Chem Chem Phys 2024; 26:4492-4504. [PMID: 38240480 DOI: 10.1039/d3cp05906e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Accurately predicting the viscosity of water confined within nanotubes is vital for various technological applications. Traditional methods have failed in this regard, necessitating a novel approach. We introduced the jump-corrected confined Stokes-Einstein (JCSE) method and now employ the same to estimate the viscosity and diffusion in superhydrophobic nanotubes. Our study covers a temperature range of 230-300 K and considers three nanotube diameters. Results show that water inside superhydrophobic nanotubes exhibits a significantly lower viscosity and higher diffusion than those inside hydrophobic nanotubes. Narrower nanotubes and lower temperatures accentuate these effects. Furthermore, water inside superhydrophobic nanotubes display a lower viscosity than bulk water, with the difference increasing at lower temperatures. This reduction is attributed to weaker water-water interactions caused by a lower water density in the interfacial region. These findings highlight the importance of interfacial water density and its influence on nanotube viscosity, shedding light on nanoscale fluid dynamics and opening avenues for diverse applications.
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Affiliation(s)
- Golam Rosul Khan
- Department of Chemistry, Indian Institute of Technology Patna, Bihar 801106, India.
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Wickramasinghe S, Hoehn A, Wetthasinghe ST, Lin H, Wang Q, Jakowski J, Rassolov V, Tang C, Garashchuk S. Theoretical Examination of the Hydroxide Transport in Cobaltocenium-Containing Polyelectrolytes. J Phys Chem B 2023; 127:10129-10141. [PMID: 37972315 DOI: 10.1021/acs.jpcb.3c04118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Polymers incorporating cobaltocenium groups have received attention as promising components of anion-exchange membranes (AEMs), exhibiting a good balance of chemical stability and high ionic conductivity. In this work, we analyze the hydroxide diffusion in the presence of cobaltocenium cations in an aqueous environment based on the molecular dynamics of model systems confined in one dimension to mimic the AEM channels. In order to describe the proton hopping mechanism, the forces are obtained from the electronic structure computed at the density-functional tight-binding level. We find that the hydroxide diffusion depends on the channel size, modulation of the electrostatic interactions by the solvation shell, and its rearrangement ability. Hydroxide diffusion proceeds via both the vehicular and structural diffusion mechanisms with the latter playing a larger role at low diffusion coefficients. The highest diffusion coefficient is observed under moderate water densities (around half the density of liquid water) when there are enough water molecules to form the solvation shell, reducing the electrostatic interaction between ions, yet there is enough space for the water rearrangements during the proton hopping. The effects of cobaltocenium separation, orientation, chemical modifications, and the role of nuclear quantum effects are also discussed.
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Affiliation(s)
- Sachith Wickramasinghe
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Alexandria Hoehn
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Shehani T Wetthasinghe
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Huina Lin
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Qi Wang
- Department of Mathematics, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Jacek Jakowski
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Vitaly Rassolov
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Chuanbing Tang
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sophya Garashchuk
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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Sharma T, Erimban S, Azad R, Nam Y, Raj R, Daschakraborty S. Investigating the Vapor-Phase Adsorption of Aroma Molecules on the Water-Vapor Interface using Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 38032075 DOI: 10.1021/acs.langmuir.3c02531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
Surfactants are amphiphilic additives primarily used to reduce the surface tension of water and manipulate its wettability on various surfaces. Recent reports suggest that volatile surfactants, such as aroma molecules, diffuse more quickly to the interface from the vapor-phase than conventional surfactants typically used in the aqueous phase. The ability to adsorb from the vapor phase, in addition to their use as cosurfactants, expands the potential applications of volatile surfactants, particularly in situations where adding surfactants from the liquid phase is difficult. Here, we present a molecular level understanding of the adsorption kinetics of linalool, a common aroma molecule, on the water interface using molecular dynamics simulations. We note that the value of surface tension while adsorption from vapor and liquid phases is dependent only on the surface coverage. A minimum surface tension of 32 ± 1.8 mN/m is obtained in both cases at a maximum surface coverage of 4.88 μmol/m2 at 300 K. We observe the extent of decrease of the H-bonds between linalool-water and linalool-linalool molecules at various surface coverages to explain the mechanism of surface tension reduction. We solve Gibb's adsorption equation to establish a correlation between the surface coverage of linalool and the corresponding bulk concentration in experiments. We investigate the free energy profile of linalool's adsorption behavior at different surface coverages and temperatures. Our report suggests that linalool adsorption onto the water interface is an enthalpy-driven process primarily dependent on the strength of the interaction between the hydroxyl group of linalool and water molecules. These insights are crucial for selecting a suitable aroma molecule for various applications that target the vapor-phase adsorption mechanism.
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Affiliation(s)
- Tonmoy Sharma
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Patna, Bihar 801106, India
| | - Shakkira Erimban
- Department of Chemistry, Indian Institute of Technology, Patna, Bihar 801106, India
| | - Rajnish Azad
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Patna, Bihar 801106, India
| | - Youngsuk Nam
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Rishi Raj
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Patna, Bihar 801106, India
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Rase D, Illathvalappil R, Singh HD, Shekhar P, Leo LS, Chakraborty D, Haldar S, Shelke A, Ajithkumar TG, Vaidhyanathan R. Hydroxide ion-conducting viologen-bakelite organic frameworks for flexible solid-state zinc-air battery applications. NANOSCALE HORIZONS 2023; 8:224-234. [PMID: 36511297 DOI: 10.1039/d2nh00455k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Adaptable polymer-based solid-state electrolytes can be a game-changer toward safe, lightweight flexible batteries. We present a robust Bakelite-type organic polymer covalently decked with viologen, triazine, and phenolic moieties. Its flexible structure with cationic viologen centers incorporates counter-balancing free hydroxide ions into the polymeric framework. By design, the aromatic groups and heteroatoms in the framework can be activated under an applied potential to prompt a push-pull drive, setting off the towing of hydroxide ions via weak electrostatic, van der Waals, and hydrogen-bond interactions. The frontier orbitals from a DFT-modeled structure certify this. The hydroxyl-polymer requires minimal KOH wetting to maintain a humid environment for Grotthuss-type transport. The hydroxide ion conductivity reaches a value of 1.4 × 10-2 S cm-1 at 80 °C and 95% RH, which is retained for over 15 h. We enhanced its practical utility by coating it as a thin solid-state separator-cum-electrolyte on readily available filter paper. The composite exhibits a conductivity of 4.5 × 10-3 S cm-1 at 80 °C and 95% RH. A zinc-air battery (ZAB) constructed using this polymer-coated paper as electrolyte yields a maximum power density of 115 mW cm-2 and high specific capacitance of 435 mA h g-1. The power density recorded for our ZAB is among the best reported for polymer electrolyte-based batteries. Subsequently, the flexible battery fabricated with IISERP-POF11_OH@FilterPaper exhibits an OCV of 1.44 V, and three batteries in series power a demo traffic signal. To underscore the efficiency of hydroxide ion transport through the complex multifunctional backbone of the polymer, we calculated the diffusion coefficient for OH- (Exp: 2.9 × 10-5 cm2 s-1; Comp. 5.2 × 10-6 cm2 s-1) using electrochemical methods and MD simulations. Climbing-edge NEB calculations reveal a large energy barrier of 2.11 eV for Zn2+ to penetrate the polymer and identify hydroxide ions within the polymer, suggesting no undesirable Zn2+ crossover. Our findings assert the readily accessible C-C-linked cationic polymer's capacity as a solid-state electrolyte for ZABs and any anion-conducting membrane.
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Affiliation(s)
- Deepak Rase
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Rajith Illathvalappil
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Himan Dev Singh
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Pragalbh Shekhar
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Liya S Leo
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Debanjan Chakraborty
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
| | - Sattwick Haldar
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Ankita Shelke
- Central NMR Facility and Physical/Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India
| | - Thalasseril G Ajithkumar
- Central NMR Facility and Physical/Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India
| | - Ramanathan Vaidhyanathan
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India.
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008, India
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