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Jia Z, Zhang J, Ji Z, Yang X, Shi C, Sun X, Guo Y. Preparation of waterborne anti-counterfeiting ink based on dual luminescent nanohybrids of bacterial cellulose nanocrystals and lanthanide‑nitrogen co-modified GQDs. Int J Biol Macromol 2024; 271:132341. [PMID: 38821792 DOI: 10.1016/j.ijbiomac.2024.132341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 05/07/2024] [Accepted: 05/11/2024] [Indexed: 06/02/2024]
Abstract
To address the growing challenge of counterfeit prevention, this study developed a novel anti-counterfeiting ink system based on bacterial cellulose nanocrystals (BCNC) and lanthanide (Er, Yb)‑nitrogen (N) co-dropped graphene quantum dots (GQDs), which exhibited both photoluminescence (PL) and upconversion photoluminescence (UCPL) fluorescent properties as well as excellent rheological characteristics. The Er/Yb/N-GQDs with positive charges were synthesized by a one-step hydrothermal method and subsequently assembled with negatively charged BCNC through electrostatic self-assembly to fabricate a novel nanohybrid, Er/Yb/N-GQDs-BCNC. Raman spectroscopy results indicated an enhancement in the graphitization of GQDs due to lanthanide modification. The TEM results demonstrated a homogeneous distribution of Er/Yb/N-GQDs on BCNC, while XRD, FTIR, and XPS analyses confirmed their physical binding, thus validating the successful synthesis of novel nanohybrids. Then, Er/Yb/N-GQDs-BCNC was introduced into PVA waterborne ink and exhibited dual anti-counterfeiting properties by emitting blue fluorescence at Em 440 nm under Ex 370 nm and green fluorescence at Em 550 nm under Ex 980 nm. Furthermore, the incorporation of BCNC significantly enhanced the thixotropic behavior and yield stress of the PVA waterborne ink. This enhancement made the dual anti-counterfeiting fluorescent ink more suitable for diversified applications on different devices and various substrates, thus providing a novel approach for convenient and rapid information encryption and high security anti-counterfeiting.
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Affiliation(s)
- Zhixin Jia
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Shandong, Zibo 255049, China; Information Technology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; National Engineering Research Center for Information Technology in Agriculture, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China; Key Laboratory of Cold Chain Logistics Technology for Agro-product, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | | | - Zengtao Ji
- Information Technology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; National Engineering Research Center for Information Technology in Agriculture, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China; Key Laboratory of Cold Chain Logistics Technology for Agro-product, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Xinting Yang
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Shandong, Zibo 255049, China; Information Technology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; National Engineering Research Center for Information Technology in Agriculture, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China; Key Laboratory of Cold Chain Logistics Technology for Agro-product, Ministry of Agriculture and Rural Affairs, Beijing 100097, China.
| | - Ce Shi
- Information Technology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; National Engineering Research Center for Information Technology in Agriculture, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China; Key Laboratory of Cold Chain Logistics Technology for Agro-product, Ministry of Agriculture and Rural Affairs, Beijing 100097, China.
| | - Xia Sun
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Shandong, Zibo 255049, China
| | - Yemin Guo
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Shandong, Zibo 255049, China
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Ma X, Neek-Amal M, Sun C. Advances in Two-Dimensional Ion-Selective Membranes: Bridging Nanoscale Insights to Industrial-Scale Salinity Gradient Energy Harvesting. ACS NANO 2024; 18:12610-12638. [PMID: 38733357 DOI: 10.1021/acsnano.3c11646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2024]
Abstract
Salinity gradient energy, often referred to as the Gibbs free energy difference between saltwater and freshwater, is recognized as "blue energy" due to its inherent cleanliness, renewability, and continuous availability. Reverse electrodialysis (RED), relying on ion-selective membranes, stands as one of the most prevalent and promising methods for harnessing salinity gradient energy to generate electricity. Nevertheless, conventional RED membranes face challenges such as insufficient ion selectivity and transport rates and the difficulty of achieving the minimum commercial energy density threshold of 5 W/m2. In contrast, two-dimensional nanostructured materials, featuring nanoscale channels and abundant functional groups, offer a breakthrough by facilitating rapid ion transport and heightened selectivity. This comprehensive review delves into the mechanisms of osmotic power generation within a single nanopore and nanochannel, exploring optimal nanopore dimensions and nanochannel lengths. We subsequently examine the current landscape of power generation using two-dimensional nanostructured materials in laboratory-scale settings across various test areas. Furthermore, we address the notable decline in power density observed as test areas expand and propose essential criteria for the industrialization of two-dimensional ion-selective membranes. The review concludes with a forward-looking perspective, outlining future research directions, including scalable membrane fabrication, enhanced environmental adaptability, and integration into multiple industries. This review aims to bridge the gap between previous laboratory-scale investigations of two-dimensional ion-selective membranes in salinity gradient energy conversion and their potential large-scale industrial applications.
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Affiliation(s)
- Xinyi Ma
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Mehdi Neek-Amal
- Department of Physics, Shahid Rajaee Teacher Training University, Tehran 1678815811, Iran
- Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
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Zhou R, Neek-Amal M, Peeters FM, Bai B, Sun C. Interlink between Abnormal Water Imbibition in Hydrophilic and Rapid Flow in Hydrophobic Nanochannels. PHYSICAL REVIEW LETTERS 2024; 132:184001. [PMID: 38759191 DOI: 10.1103/physrevlett.132.184001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/29/2024] [Accepted: 03/21/2024] [Indexed: 05/19/2024]
Abstract
Nanoscale extension and refinement of the Lucas-Washburn model is presented with a detailed analysis of recent experimental data and extensive molecular dynamics simulations to investigate rapid water flow and water imbibition within nanocapillaries. Through a comparative analysis of capillary rise in hydrophilic nanochannels, an unexpected reversal of the anticipated trend, with an abnormal peak, of imbibition length below the size of 3 nm was discovered in hydrophilic nanochannels, surprisingly sharing the same physical origin as the well-known peak observed in flow rate within hydrophobic nanochannels. The extended imbibition model is applicable across diverse spatiotemporal scales and validated against simulation results and existing experimental data for both hydrophilic and hydrophobic nanochannels.
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Affiliation(s)
- Runfeng Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Mehdi Neek-Amal
- Department of Physics, Shahid Rajaee Teacher Training University, 16875-163 Lavizan, Tehran, Iran
- Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Francois M Peeters
- Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
- Departamento de Física, Universidade Federal do Ceará, Fortaleza-CE 60455-760, Brazil
| | - Bofeng Bai
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
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Rezlerová E, Moučka F, Předota M, Lísal M. Structure and self-diffusivity of mixed-cation electrolytes between neutral and charged graphene sheets. J Chem Phys 2024; 160:094701. [PMID: 38426518 DOI: 10.1063/5.0188104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/12/2024] [Indexed: 03/02/2024] Open
Abstract
Graphene-based applications, such as supercapacitors or capacitive deionization, take place in an aqueous environment, and they benefit from molecular-level insights into the behavior of aqueous electrolyte solutions in single-digit graphene nanopores with a size comparable to a few molecular diameters. Under single-digit graphene nanoconfinement (smallest dimension <2 nm), water and ions behave drastically different than in the bulk. Most aqueous electrolytes in the graphene-based applications as well as in nature contain a mix of electrolytes. We study several prototypical aqueous mixed alkali-chloride electrolytes containing an equimolar fraction of Li/Na, Li/K, or Na/K cations confined between neutral and positively or negatively charged parallel graphene sheets. The strong hydration shell of small Li+ vs a larger Na+ or large K+ with weaker or weak hydration shells affects the interplay between the ions's propensity to hydrate or dehydrate under the graphene nanoconfinement and the strength of the ion-graphene interactions mediated by confinement-induced layered water. We perform molecular dynamics simulations of the confined mixed-cation electrolytes using the effectively polarizable force field for electrolyte-graphene systems and focused on a relation between the electrochemical adsorption and structural properties of the water molecules and ions and their diffusion behavior. The simulations show that the one-layer nanoslits have the biggest impact on the ions' adsorption and the water and ions' diffusion. The positively charged one-layer nanoslits only allow for Cl- adsorption and strengthen the intermolecular bonding, which along with the ultrathin confinement substantially reduces the water and Cl- diffusion. In contrast, the negatively charged one-layer nanoslits only allow for adsorption of weakly hydrated Na+ or K+ and substantially break up the non-covalent bond network, which leads to the enhancement of the water and Na+ or K+ diffusion up to or even above the bulk diffusion. In wider nanoslits, cations adsorb closer to the graphene surfaces than Cl-'s with preferential adsorption of a weakly hydrated cation over a strongly hydrated cation. The positive graphene charge has an intuitive effect on the adsorption of weakly hydrated Na+'s or K+'s and Cl-'s and a counterintuitive effect on the adsorption of strongly hydrated Li+'s. On the other hand, the negative surface charge has an intuitive effect on the adsorption of both types of cations and only mild intuitive or counterintuitive effects on the Cl- adsorption. The diffusion of water molecules and ions confined in the wider nanoslits is reduced with respect to the bulk diffusion, more for the positive graphene charge, which strengthened the intermolecular bonding, and less for the negative surface charge, which weakened the non-covalent bond network.
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Affiliation(s)
- Eliška Rezlerová
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Rozvojová 135/1, Prague, Czech Republic
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Ústí nad Labem, Pasteurova 3544/1, Ústí n. Lab., Czech Republic
| | - Filip Moučka
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Rozvojová 135/1, Prague, Czech Republic
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Ústí nad Labem, Pasteurova 3544/1, Ústí n. Lab., Czech Republic
| | - Milan Předota
- Department of Physics, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Martin Lísal
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Rozvojová 135/1, Prague, Czech Republic
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Ústí nad Labem, Pasteurova 3544/1, Ústí n. Lab., Czech Republic
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Ferreira de Souza N, Picard C, Franco LFM, Coasne B. Thermal Conductivity of a Fluid-Filled Nanoporous Material: Underlying Molecular Mechanisms and the Rattle Effect. J Phys Chem B 2024. [PMID: 38438957 DOI: 10.1021/acs.jpcb.3c07088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Nanoporous materials are central to the energy and environmental crisis, with key applications in adsorption, separation, and catalysis. While confinement and surface effects on fluids severely confined in their porosity are well documented, the thermal behavior of nanoporous solids subjected to fluid adsorption remains puzzling in many aspects. With striking phenomena such as the so-called rattle effect, through which fluid/solid collisions decrease the overall thermal conductivity, the solid thermal conductivity and, more generally, heat transfer and dispersion in these complex systems challenge classical approaches (e.g., mixing rules including effective medium approaches fail to capture such effects as shown here). In particular, a robust molecular framework to describe the crossover between the decrease in thermal conductivity through the rattle effect in very narrow pores and the increase in thermal conductivity when replacing vacuum with a fluid phase in larger pores is still missing. Here, using a prototypical model of fluid-filled nanoporous materials (a Lennard-Jones phase confined in an all-silica zeolite), we perform a molecular simulation study to shed light on the parameters that govern the rattle effect in nanoporous solids. First, by varying the fluid/fluid, fluid/solid, and solid/solid interaction strengths as well as the fluid number density and mass density, we unravel the ingredients that lead to the essential coupling between fluid adsorption and phonon transport. Second, despite this complex interplay, inspired by pioneering molecular approaches on the rattle effect, we show that all data obey a simple statistical physics model that relies on the change in the speed of sound due to the fluid adsorbed density and the decrease in phonon lifetime due to scattering by fluid molecules. This framework, which provides a simple formalism to rationalize the thermal behavior of this class of solid/fluid composites, points to a decrease in thermal conductivity upon fluid confinement (up to 30% in some cases). Such an effect paves the way for the design of novel applications involving fluids in interaction with nanoporous materials.
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Affiliation(s)
- Nikolas Ferreira de Souza
- School of Chemical Engineering, Department of Chemical Systems Engineering, University of Campinas, 13083-852 Campinas, Brazil
- University Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - Cyril Picard
- University Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - Luís Fernando Mercier Franco
- School of Chemical Engineering, Department of Chemical Systems Engineering, University of Campinas, 13083-852 Campinas, Brazil
| | - Benoit Coasne
- University Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
- Institut Laue-Langevin, F-38042 Grenoble, France
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Kellouai W, Barrat JL, Judeinstein P, Plazanet M, Coasne B. On De Gennes narrowing of fluids confined at the molecular scale in nanoporous materials. J Chem Phys 2024; 160:024113. [PMID: 38193554 DOI: 10.1063/5.0186956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 12/10/2023] [Indexed: 01/10/2024] Open
Abstract
Beyond well-documented confinement and surface effects arising from the large internal surface and severely confining porosity of nanoporous hosts, the transport of nanoconfined fluids remains puzzling in many aspects. With striking examples such as memory, i.e., non-viscous effects, intermittent dynamics, and surface barriers, the dynamics of fluids in nanoconfinement challenge classical formalisms (e.g., random walk, viscous/advective transport)-especially for molecular pore sizes. In this context, while molecular frameworks such as intermittent Brownian motion, free volume theory, and surface diffusion are available to describe the self-diffusion of a molecularly confined fluid, a microscopic theory for collective diffusion (i.e., permeability), which characterizes the flow induced by a thermodynamic gradient, is lacking. Here, to fill this knowledge gap, we invoke the concept of "De Gennes narrowing," which relates the wavevector-dependent collective diffusivity D0(q) to the fluid structure factor S(q). First, using molecular simulation for a simple yet representative fluid confined in a prototypical solid (zeolite), we unravel an essential coupling between the wavevector-dependent collective diffusivity and the structural ordering imposed on the fluid by the crystalline nanoporous host. Second, despite this complex interplay with marked Bragg peaks in the fluid structure, the fluid collective dynamics is shown to be accurately described through De Gennes narrowing. Moreover, in contrast to the bulk fluid, the departure from De Gennes narrowing for the confined fluid in the macroscopic limit remains small as the fluid/solid interactions in severe confinement screen collective effects and, hence, weaken the wavevector dependence of collective transport.
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Affiliation(s)
- Wanda Kellouai
- Univ. Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - Jean-Louis Barrat
- Univ. Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
| | | | - Marie Plazanet
- Univ. Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - Benoit Coasne
- Univ. Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
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Li M, Wang D, Wang L. The curvature effect on the distribution behavior of nonpolar atoms in nano-confined space. Phys Chem Chem Phys 2023; 25:31960-31973. [PMID: 37975210 DOI: 10.1039/d3cp04399a] [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
The chemical and physical properties of nonpolar atoms are obviously affected by confinement. A curvature-based theoretical model for helium particles distributed in carbon nanotubes is proposed by considering the L-J pair potential and the Boltzmann distribution. The potential gap formed by the non-bonded interaction between a helium atom and a carbon nanotube surface leads to a layered structure distribution with high density near the surface. By assuming adsorption as a competition between the potential gap and the thermal energy, the desorption critical temperature is discussed for helium adsorbed on the layer, which is confirmed to be a monotonic decreasing function of nanotube diameter. The helium atom distribution relations between the nanotube diameter, temperature and the potential gap obtained from molecular dynamics simulations are consistent with the curvature-based model predictions. The adsorption ratio is defined by the numbers of particles adsorbed on the near surface layered structure over total particle numbers, which decreases with the increase of temperature and carbon nanotube diameter. The curvature-based model is further confirmed by studying krypton and argon atoms in the appendix. This work provides a simple model to predict the distribution behavior and reveals the curvature effect on the distribution and adsorption of non-polar atoms confined in nano-space, which could be important for a better understanding of the chemical and physical properties of gas storage in the nano-confined space.
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Affiliation(s)
- Mingqian Li
- State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, No. 29 Yudao Street, Nanjing 210016, China.
| | - Dan Wang
- State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, No. 29 Yudao Street, Nanjing 210016, China.
| | - Lifeng Wang
- State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, No. 29 Yudao Street, Nanjing 210016, China.
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Zhang Y, Huang R, Iepure M, Merriman S, Min Y. Geocolloidal interactions and relaxation dynamics under nanoconfinement: Effects of salinity and particle concentration. J Colloid Interface Sci 2023; 656:200-213. [PMID: 37989053 DOI: 10.1016/j.jcis.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 10/28/2023] [Accepted: 11/01/2023] [Indexed: 11/23/2023]
Abstract
HYPOTHESIS Energy-related contaminants are frequently associated with geocolloids that translocate in underground fissures with dimensions comparable with geocolloids. To assess the transport and impact of energy-related contaminants in geological systems, fundamental understandings of interfacial behaviors of nanoparticles under confinement is imperative. We hypothesize that the dynamic properties of geocolloids, as well as their dependence on aqueous medium conditions would deviate from bulk behaviors under nanoconfinement. EXPERIMENTS Force profiles and rheological properties of 50 nm silica nanoparticles in aqueous media confined between mica surfaces as a function of surface separation, particle concentrations, and salinity were measured utilizing the surface forces apparatus. FINDINGS Force profiles revealed the critical surface separation for nonlinear rheological behaviors coincides with the onset of exponential repulsion between mica surfaces. When salts were absent, the normal forces and viscosity values of colloidal suspensions resembled pure water. In contrast, with salts, the force profiles and corresponding critical length scales were found to be highly sensitive to the particle concentration and the degree of confinement. A Newtonian to shear-thinning transition was captured with increasing degrees of confinement. Our results show that the interplay among confinement, particle, and ionic concentrations can alter the interparticle forces and rheological responses of true nanosized-colloidal suspensions and thus their transport behaviors under nanoconfinement for the first time.
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Affiliation(s)
- Yuanzhong Zhang
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Rundong Huang
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Monica Iepure
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Stephen Merriman
- School of Polymer Science and Polymer Engineering, University of Akron, 44325 OH, USA
| | - Younjin Min
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA; Material Science and Engineering Program, University of California, Riverside, 92521 CA, USA.
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Chogani A, Plümper O. Decoding the nanoscale porosity in serpentinites from multidimensional electron microscopy and discrete element modelling. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY. BEITRAGE ZUR MINERALOGIE UND PETROLOGIE 2023; 178:78. [PMID: 38616804 PMCID: PMC11008076 DOI: 10.1007/s00410-023-02062-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 09/28/2023] [Indexed: 04/16/2024]
Abstract
Serpentinites, widespread in Earth's lithosphere, exhibit inherent nanoporosity that may significantly impact their geochemical behaviour. This study provides a comprehensive investigation into the characteristics, scale dependence, and potential implications of nanoporosity in lizardite-dominated serpentinites. Through a combination of multidimensional imaging techniques and molecular-dynamics-based discrete element modelling, we reveal that serpentinites function as nanoporous media with pore sizes predominantly less than 100 nm. Crystallographic relationships between olivine, serpentine, and nanoporosity are explored, indicating a lack of significant correlations. Instead, stochastic growth and random packing of serpentine grains within mesh cores may result in interconnected porosity. The analysis of pore morphology suggests that the irregular pore shapes align with the crystal form of serpentine minerals. Furthermore, the nanoporosity within brucite-rich layers at the serpentine-olivine interface is attributed to delamination along weak van der Waals planes, while pore formation within larger brucite domains likely results from low-temperature alteration processes. The fractal nature of the pore size distribution and the potential interconnectivity of porosity across different scales further support the presence of a pervasive nanoporous network within serpentinites. Confinement within these nanopores may introduce unique emergent properties, potentially influencing fluid transport, mineral solubility, and chemical reactions. As such, these processes may have profound implications for the geochemical evolution of serpentinites.
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Affiliation(s)
- Alireza Chogani
- Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
| | - Oliver Plümper
- Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
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Cao Z, Wang Y, Lorsung C, Barati Farimani A. Neural network predicts ion concentration profiles under nanoconfinement. J Chem Phys 2023; 159:094702. [PMID: 37655768 DOI: 10.1063/5.0147119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 06/23/2023] [Indexed: 09/02/2023] Open
Abstract
Modeling the ion concentration profile in nanochannel plays an important role in understanding the electrical double layer and electro-osmotic flow. Due to the non-negligible surface interaction and the effect of discrete solvent molecules, molecular dynamics (MD) simulation is often used as an essential tool to study the behavior of ions under nanoconfinement. Despite the accuracy of MD simulation in modeling nanoconfinement systems, it is computationally expensive. In this work, we propose neural network to predict ion concentration profiles in nanochannels with different configurations, including channel widths, ion molarity, and ion types. By modeling the ion concentration profile as a probability distribution, our neural network can serve as a much faster surrogate model for MD simulation with high accuracy. We further demonstrate the superior prediction accuracy of neural network over XGBoost. Finally, we demonstrated that neural network is flexible in predicting ion concentration profiles with different bin sizes. Overall, our deep learning model is a fast, flexible, and accurate surrogate model to predict ion concentration profiles in nanoconfinement.
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Affiliation(s)
- Zhonglin Cao
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Yuyang Wang
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Cooper Lorsung
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Amir Barati Farimani
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- Machine Learning Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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11
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Rezlerová E, Moučka F, Předota M, Lísal M. Structure and self-diffusivity of alkali-halide electrolytes in neutral and charged graphene nanochannels. Phys Chem Chem Phys 2023; 25:21579-21594. [PMID: 37548441 DOI: 10.1039/d3cp03027j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Understanding the microscopic behaviour of aqueous electrolyte solutions in graphene-based ultrathin nanochannels is important in nanofluidic applications such as water purification, fuel cells, and molecular sensing. Under extreme confinement (<2 nm), the properties of water and ions differ drastically from those in the bulk phase. We studied the structural and diffusion behaviour of prototypical aqueous solutions of electrolytes (LiCl, NaCl, and KCl) confined in both neutral and positively-, and negatively-charged graphene nanochannels. We performed molecular dynamics simulations of the solutions in the nanochannels with either one, two- or three-layer water structures using the effectively polarisable force field for graphene. We analysed the structure and intermolecular bond network of the confined solutions along with their relation to the self-diffusivity of water and ions. The simulations show that Na and K cations can more easily rearrange their solvation shells under the graphene nanoconfinement and adsorb on the graphene surfaces or dissolve in the confinement-induced layered water than the Li cation. The negative surface charge together with the presence of ions orient water molecules with hydrogens towards the graphene surfaces, which in turn weakens the intermolecular bond network. The one-layer nanochannels have the biggest effect on the water structure and intermolecular bonding as well as on the adsorption of ions with only co-ions entering these nanochannels. The self-diffusivity of confined water is strongly reduced with respect to the bulk water and decreases with diminishing nanochannel heights except for the negatively-charged one-layer nanochannel. The self-diffusivity of ions also decreases with the reducing the nanochannel heights except for the self-diffusivity of cations in the negatively-charged one-layer nanochannel, evidencing cooperative diffusion of confined water and ions. Due to the significant break-up of the intermolecular bond network in the negatively-charged one-layer nanochannel, self-diffusion coefficients of water and cations exceed those for the two- and three-layer nanochannels and become comparable to the bulk values.
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Affiliation(s)
- Eliška Rezlerová
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Prague, Czech Republic.
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Úst nad Labem, Ústín. Lab., Czech Republic
| | - Filip Moučka
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Prague, Czech Republic.
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Úst nad Labem, Ústín. Lab., Czech Republic
| | - Milan Předota
- Department of Physics, Faculty of Science, University of South Bohemia, České Budě jovice, Czech Republic
| | - Martin Lísal
- Research Group of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Prague, Czech Republic.
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Úst nad Labem, Ústín. Lab., Czech Republic
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12
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Wang D, Lippmann M, Gäding J, Ehnes A, Novikov D, Meißner R, Seeck OH. Orientation order of a nonpolar molecular fluid compressed into a nanosmall space. NANOSCALE 2023; 15:8019-8028. [PMID: 37070420 DOI: 10.1039/d2nr06330a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The ordering structures of non-polar carbon tetrachloride liquid compressed to nano-scales between parallel substrates is studied in this work. The theoretical considerations show that the potential well formed by the confined parallel substrates induces orientational ordering of non-polar molecules. Through molecular dynamic (MD) simulations, the relations between various ordered structures of a non-polar liquid (carbon tetrachloride) and the confined gap size are demonstrated. The density distribution shows that the confinement does affect the ordering modes and induces an orientational ordering of molecules at the solid-liquid interface under extreme confinement conditions. This molecular orientation suggested from the theoretical model and MD simulation is directly supported by the experimental studies for the first time. The X-ray reflectivity data reveal a strong layering effect with splitting of the density profile in C and Cl-rich sublayers. The investigation shows that the liquid structure factor in confinement has a characteristic length similar to the short-range ordering in bulk, but the confined structure is strongly influenced by the surface potential and the interface properties. This introduces preferred molecular orientation and ordering which are not favorable in the bulk phase. As the orientational ordering is closely related to crystallization, our results provide a new perspective to control the crystallization in nano-confined space by compression.
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Affiliation(s)
- Dan Wang
- State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, No. 29 Yudao Street, Nanjing 210016, China
| | - Milena Lippmann
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany.
| | | | - Anita Ehnes
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany.
| | - Dmitri Novikov
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany.
| | - Robert Meißner
- Hamburg University of Technology, 21073 Hamburg, Germany
- Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
| | - Oliver H Seeck
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany.
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13
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Zhao Z, Jin Y, Zhou R, Sun C, Huang X. Unexpected Behavior in Thermal Conductivity of Confined Monolayer Water. J Phys Chem B 2023; 127:4090-4098. [PMID: 37105181 DOI: 10.1021/acs.jpcb.2c07506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Monolayer water can be formed under extreme confinement and will present distinctive thermodynamic properties compared with bulk water. In this work, we perform molecular dynamics simulations to study the thermal conductivity of monolayer water confined in graphene channels, finding an unexpected way of thermal conductivity of monolayer water dependent on its number density, which has a close correlation with the structure of water. The monolayer water is in an amorphous state, and its thermal conductivity increases linearly with the area density when the water density is low at first. Then, the thermal conductivity increases as the number density of water rises, which is attributed to the formation of a crystal structure and the reduction of crystal defects as the number of water molecules increases. After reaching the zenith, the thermal conductivity decreases rapidly owing to the formation of a wrinkle structure of monolayer water with excessive water molecules, which weakens the phonon dispersion. Moreover, we further investigate the remarkable effects of the channel height on both the structure and thermal conductivity of monolayer water. In summary, this study demonstrates the close connection between the thermal conductivity of monolayer water and its structure, contributing to not only expanding the understanding of the thermodynamic property of nanoconfined water but also benefiting the engineering applications for nanofluidics.
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Affiliation(s)
- Zhixiang Zhao
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Shaanxi 710048, China
| | - Yonghui Jin
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Shaanxi 710048, China
| | - Runfeng Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Shaanxi 710049, China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Shaanxi 710049, China
| | - Xiang Huang
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Shaanxi 710048, China
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14
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Hou Y, Ling Y, Wang Y, Wang M, Chen Y, Li X, Hou X. Learning from the Brain: Bioinspired Nanofluidics. J Phys Chem Lett 2023; 14:2891-2900. [PMID: 36927003 DOI: 10.1021/acs.jpclett.2c03930] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The human brain completes intelligent behaviors such as the generation, transmission, and storage of neural signals by regulating the ionic conductivity of ion channels in neuron cells, which provides new inspiration for the development of ion-based brain-like intelligence. Against the backdrop of the gradual maturity of neuroscience, computer science, and micronano materials science, bioinspired nanofluidic iontronics, as an emerging interdisciplinary subject that focuses on the regulation of ionic conductivity of nanofluidic systems to realize brain-like functionalities, has attracted the attention of many researchers. This Perspective provides brief background information and the state-of-the-art progress of nanofluidic intelligent systems. Two main categories are included: nanofluidic transistors and nanofluidic memristors. The prospects of nanofluidic iontronics' interdisciplinary progress in future artificial intelligence fields such as neuromorphic computing or brain-computer interfaces are discussed. This Perspective aims to give readers a clear understanding of the concepts and prospects of this emerging interdisciplinary field.
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Affiliation(s)
- Yaqi Hou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- The Institute of Flexible Electronics (IFE, Future Technologies), Xiamen University, Xiamen 361005, China
| | - Yixin Ling
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yanqiong Wang
- The Institute of Flexible Electronics (IFE, Future Technologies), Xiamen University, Xiamen 361005, China
| | - Miao Wang
- Institute of Artificial Intelligence, Xiamen University, Xiamen 361005, China
- College of Materials, Xiamen University, Xiamen 361005, China
| | - Yeyun Chen
- Institute of Artificial Intelligence, Xiamen University, Xiamen 361005, China
| | - Xipeng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- Binzhou Institute of Technology, Binzhou, 256600, China
| | - Xu Hou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Jiujiang Research Institute, College of Physical Science and Technology, Xiamen University, Xiamen 361005, China
- Institute of Artificial Intelligence, Xiamen University, Xiamen 361005, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361102, China
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15
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Photosensitive ion channels in layered MXene membranes modified with plasmonic gold nanostars and cellulose nanofibers. Nat Commun 2023; 14:359. [PMID: 36690639 PMCID: PMC9870870 DOI: 10.1038/s41467-023-36039-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 01/11/2023] [Indexed: 01/24/2023] Open
Abstract
Ion channels transduce external stimuli into ion-transport-mediated signaling, which has received considerable attention in diverse fields such as sensors, energy harvesting devices, and desalination membrane. In this work, we present a photosensitive ion channel based on plasmonic gold nanostars (AuNSs) and cellulose nanofibers (CNFs) embedded in layered MXene nanosheets. The MXene/AuNS/CNF (MAC) membrane provides subnanometer-sized ionic pathways for light-sensitive cationic flow. When the MAC nanochannel is exposed to NIR light, a photothermal gradient is formed, which induces directional photothermo-osmotic flow of nanoconfined electrolyte against the thermal gradient and produces a net ionic current. MAC membrane exhibits enhanced photothermal current compared with pristine MXene, which is attributed to the combined photothermal effects of plasmonic AuNSs and MXene and the widened interspacing of the MAC composite via the hydrophilic nanofibrils. The MAC composite membranes are envisioned to be applied in flexible ionic channels with ionogels and light-controlled ionic circuits.
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16
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Wang Z, Li S, Zhang X, Su J. Water transport through a graphene channel with different cross-sectional shapes. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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17
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Sun Z, Kang Y, Li S. Elastic Properties of Confined Fluids in Nanopores: An Acoustic-Propagation Model. J Phys Chem B 2022; 126:8010-8020. [PMID: 36179366 DOI: 10.1021/acs.jpcb.2c05125] [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
Following the compressibility route in statistical mechanics, the local isothermal modulus is derived for nanoconfined fluids. Based on this inhomogeneous modulus, an acoustic-propagation model (APM) is first proposed for averaged isothermal modulus in the pore. By utilizing the density profiles obtained from classical density functional theory, the inhomogeneous modulus of supercritical methane in the graphite slit pore is calculated. It is found that the profile of the modulus in the pore is out of phase with that of density. Further, employing the proposed APM method, the averaged isothermal modulus is calculated, and the effects of pressure, pore size, and temperature on the averaged modulus are investigated. It is found that (i) averaged modulus obtained from APM method still satisfies the Tait-Murnaghan (TM) equation, (ii) the averaged modulus is proportional to the reciprocal pore width for wider pores, while it oscillates with the reciprocal pore width for narrower pores, and (iii) the reciprocal modulus is proportional to temperature, while the linearization coefficient is insensitive to the pore size. These findings bear important implications for understanding the elasticity in fluid-saturated nanoporous media and may shed light on the capture or storage of special gases in the fields of geochemistry and geophysics.
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Affiliation(s)
- Zongli Sun
- Department of Mathematics and Physics, North China Electric Power University, Baoding071003, China.,Hebei Key Laboratory of Physics and Energy Technology, Baoding071003, China
| | - Yanshuang Kang
- College of Science, Hebei Agricultural University, Baoding071001, China
| | - Songtao Li
- Department of Mathematics and Physics, North China Electric Power University, Baoding071003, China.,Hebei Key Laboratory of Physics and Energy Technology, Baoding071003, China
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18
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Zhao B, Zhou R, Sun C, Bai B. PVT properties and diffusion characteristics of H2O/H2/CO2 mixtures in graphite nanoslits. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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Ion-induced oil–water wettability alteration of rock surfaces. Part III: Ion-bridging interactions between oil and solid. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Li Y, Wang GJ. How to produce confidence intervals instead of confidence tricks: Representative sampling for molecular simulations of fluid self-diffusion under nanoscale confinement. J Chem Phys 2022; 156:114113. [DOI: 10.1063/5.0081707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ergodicity (or at least the tantalizing promise of it) is a core animating principle of molecular-dynamics (MD) simulations: Put simply, sample for long enough (in time), and you will make representative visits to states of a system all throughout phase space, consistent with the desired statistical ensemble. However, one is not guaranteed a priori that the chosen window of sampling in a production run is sufficiently long to avoid problematically non-ergodic observations; one is also not guaranteed that successive measurements of an observable are statistically independent of each other. In this paper, we investigate several particularly striking and troublesome examples of statistical correlations in MD simulations of nanoconfined fluids, which have profound implications on the quantification of uncertainty for transport phenomena in these systems. In particular, we show that these correlations can lead to confidence intervals on the fluid self-diffusion coefficient that are dramatically overconfident and estimates of this transport quantity that are simply inaccurate. We propose a simple approach—based on the thermally accelerated decorrelation of fluid positions and momenta—that ameliorates these issues and improves our confidence in MD measurements of nanoconfined fluid transport properties. We demonstrate that the formation of faithful confidence intervals for measurements of self-diffusion under nanoscale confinement typically requires at least 20 statistically independent samples, and potentially more depending on the sampling technique used.
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Affiliation(s)
- Yuanhao Li
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Gerald J. Wang
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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21
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Tan Q, Fan Y, Song Z, Chen J, Chen L. Effects of interlayer spacing and oxidation degree of graphene oxide nanosheets on water permeation: a molecular dynamics study. J Mol Model 2022; 28:57. [PMID: 35137256 DOI: 10.1007/s00894-022-05045-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 01/28/2022] [Indexed: 11/25/2022]
Abstract
Graphene oxide (GO) membranes have shown great potential in the applications of water filtration and desalination. The flow behavior and structural properties of water molecules through GO nanochannels are still under debate. In this work, molecular dynamics simulations were performed to explore the effects of interlayer spacing and oxidation degree of GO nanochannels on water transport. The results show that GO nanosheets have strong adsorption capacity. The adsorbed layer of water molecules on GO surface is thermodynamically stable and not easy to flow. When the interlayer spacing falls into the range of 0.6 ~ 1.0 nm, water molecules form into single or double adsorbed layers between two GO nanosheets. When the interlayer spacing is bigger than 1.2 nm, the other water layers in the middle of nanochannel become disordered. Taking the separation performance based on size exclusion into consideration, the most suitable interlayer spacing for water nanofiltration is approximate 1.2 nm, which has one flowing layer of water molecules. Oxygen-containing groups are unfavorable for water permeation, as more and more hydrogen bonds prevent water flowing on GO surface with the increasing oxidation degree. Our simulation results may help to improve the design of GO nanofiltration membranes for water treatment.
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Affiliation(s)
- Qiong Tan
- Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China
| | - Yan Fan
- Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China
| | - Zailing Song
- Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China
| | - Junlang Chen
- Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China.
| | - Liang Chen
- Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China
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22
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Zhu S, Yu H, Yan G, Li J, Cao A, Sun C. Miscibility Process of Hydrocarbon Mixture Gas and Crude Oil: Insights from Molecular Dynamics. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c01392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shaohua Zhu
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Hongwei Yu
- State Key Laboratory of Enhanced Oil Recovery, PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China
| | - Gengping Yan
- Research Institute of Petroleum Exploration and Development, PetroChina Tarim Oilfield, XinJiang 841000, China
| | - Jun Li
- Research Institute of Petroleum Exploration and Development, PetroChina Tarim Oilfield, XinJiang 841000, China
| | - An Cao
- Research Institute of Petroleum Exploration and Development, PetroChina Tarim Oilfield, XinJiang 841000, China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
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23
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Sun C, Zhou R, Zhao Z, Bai B. Unveiling the hydroxyl-dependent viscosity of water in graphene oxide nanochannels via molecular dynamics simulations. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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24
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Bergamasco L, Morciano M, Fasano M. Effect of water nanoconfinement on the dynamic properties of paramagnetic colloidal complexes. Phys Chem Chem Phys 2021; 23:16948-16957. [PMID: 34338258 DOI: 10.1039/d1cp00708d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The anomalous behavior of confined water at the nanoscale has remarkable implications in a number of nanotechnological applications. In this work, we analyze the effect of water self-diffusion on the dynamic properties of a solvated gadolinium-based paramagnetic complex, typically used for contrast enhancement in magnetic resonance imaging. In particular, we examine the effect of silica-based nanostructures on water behavior in the proximity of the paramagnetic complex via atomistic simulations, and interpret the resulting tumbling dynamics in the light of the local solvent modification based on the Lipari-Szabo formalism and of the fractional Stokes-Einstein relation. It is found that the local water confinement induces an increased "stiffness" on the outer sphere of the paramagnetic complex, which eventually reduces its tumbling properties. These model predictions are found to explain well the relaxivity enhancement observed experimentally by confining paramagnetic complexes into porous nanoconstructs, and thus offer mechanistic guidelines to design improved contrast agents for imaging applications.
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Affiliation(s)
- Luca Bergamasco
- Department of Energy, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
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25
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Biswas P, Sen D, Prasher M, Sarkar SK, Dasgupta K. Confinement driven anomalous freezing in nano porous spray dried microspheres. NANOTECHNOLOGY 2021; 32:385707. [PMID: 34116521 DOI: 10.1088/1361-6528/ac0ab6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/11/2021] [Indexed: 06/12/2023]
Abstract
One-step evaporative jamming of colloidal silica particles in contact-free spray droplets resulted in well-defined powder micro-granules with interstitial nanopores. This paper reports the anomalous freezing behaviour of confined water in the microspheres synthesized using spray drying. It has been revealed that the freezing point of water in these microspheres gets significantly lowered (∼-45 °C) owing to the confinement effect. Thermoporometry results are corroborated with the structural details obtained using complementary techniques of gas adsorption measurements and small-angle x-ray scattering.
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Affiliation(s)
- Priyanka Biswas
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India
- Homi Bhabha National Institute, Mumbai-400094, India
| | - Debasis Sen
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India
- Homi Bhabha National Institute, Mumbai-400094, India
| | - Meenu Prasher
- Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Sudip Kumar Sarkar
- Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Kinshuk Dasgupta
- Homi Bhabha National Institute, Mumbai-400094, India
- Glass and Advanced Materials Division, Materials Group, Bhabha Atomic Research Centre, Mumbai-400085, India
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26
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Ion-induced oil–water wettability alteration of rock surfaces. Part II: Base interactions between oil and solid. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2021.116521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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27
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Zeng Z, Song R, Zhang S, Han X, Zhu Z, Chen X, Wang L. Biomimetic N-Doped Graphene Membrane for Proton Exchange Membranes. NANO LETTERS 2021; 21:4314-4319. [PMID: 33848172 DOI: 10.1021/acs.nanolett.1c00813] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Proton exchange membranes (PEMs) with both high selectivity and high permeance are of great demand in hydrogen-based applications, especially in fuel cells. Although graphene membranes have shown high selectivity of protons over other ions and molecules, the relatively low permeance of protons through perfect pristine graphene restricts its practical applications. Inspired by the nitrogen-assisted proton transport in biological systems, we introduced N-doping to increase the proton permeance and proposed a type of N-doped graphene membranes (NGMs) for proton exchange, which have both high proton permeance and high selectivity. Compared to the state-of-the-art commercial PEMs, the NGMs show significant increases in both areal proton conductivity (2-3 orders of magnitude) and selectivity of proton to methanol (1-2 orders of magnitude). The work realized the controllable tuning of proton permeance of the graphene membrane with N-doping and developed a new type of graphene-based PEMs with high performance for practical applications.
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Affiliation(s)
- Zhiyang Zeng
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Ruiyang Song
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Shengping Zhang
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xiao Han
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Zhen Zhu
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Xiaobo Chen
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Luda Wang
- Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
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28
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Sun C, Zhou R, Zhao Z, Bai B. Extending the Classical Continuum Theory to Describe Water Flow through Two-Dimensional Nanopores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6158-6167. [PMID: 33969992 DOI: 10.1021/acs.langmuir.1c00298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Water flow through two-dimensional nanopores has attracted significant attention owing to the promising water purification technology based on atomically thick membranes. However, the theoretical description of water flow in nanopores based on the classical continuum theory is very challenging owing to the pronounced entrance/exit effects. Here, we extend the classical Hagen-Poiseuille equation for describing the relationship between flow rate and pressure loss in laminar tube flow to two-dimensional nanopores. A totally theoretical model is established by appropriately considering the velocity slip on pore surfaces both in the friction pressure loss and entrance/exit pressure loss. Based on molecular dynamics simulations of water flow through graphene nanopores, it is shown that the model can not only well predict the overall flow rate but also give a good estimation of the velocity profiles. As the pore radius and length increase, the model can reduce to the equations applicable to the fluid flow in infinitely/finitely long nanotubes, thin orifices, and macroscale tubes, showing an accurate prediction of the existing experimental and simulation data of the water flow through nanotubes and nanopores in the literature. Namely, the presented model is a unified model that can uniformly describe the fluid flow from nanoscales to macroscales by modifying the classical continuum theory.
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Affiliation(s)
- Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Runfeng Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Zhixiang Zhao
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, China
| | - Bofeng Bai
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
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29
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Sun C, Luo K, Zhou R, Bai B. Theoretical description of molecular permeation via surface diffusion through graphene nanopores. Phys Chem Chem Phys 2021; 23:7057-7065. [PMID: 33690758 DOI: 10.1039/d0cp05629d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We establish a theoretical model to describe the surface molecular permeation through two-dimensional graphene nanopores based on the surface diffusion equation and Fick's law. The model is established by considering molecular adsorption and desorption from the surface adsorption layer and the molecular diffusion and concentration gradient on the graphene surface. By comparing with the surface flux obtained from molecular dynamics simulations, it is shown that the model can predict well the overall permeation flux especially for strongly adsorbed molecules (i.e. CO2 and H2S) on graphene surfaces. Although good agreement between the theoretical and simulated density distribution is hard to achieve owing to the large uncertainty in the calculation of surface diffusion coefficients based on the Einstein equation, the model itself is very competent to describe the surface molecular permeation both from the aspects of the overall permeation flux and detailed density distribution. This model is believed to supplement the theoretical description of molecular permeation through graphene nanopores and provide a good reference for the description of mass transport through two-dimensional porous materials.
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Affiliation(s)
- Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, China.
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30
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Hamid I, Jalali H, Peeters FM, Neek-Amal M. Abnormal in-plane permittivity and ferroelectricity of confined water: From sub-nanometer channels to bulk. J Chem Phys 2021; 154:114503. [PMID: 33752365 DOI: 10.1063/5.0038359] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Dielectric properties of nano-confined water are important in several areas of science, i.e., it is relevant in the dielectric double layer that exists in practically all heterogeneous fluid-based systems. Molecular dynamics simulations are used to predict the in-plane dielectric properties of confined water in planar channels of width ranging from sub-nanometer to bulk. Because of suppressed rotational degrees of freedom near the confining walls, the dipole of the water molecules tends to be aligned parallel to the walls, which results in a strongly enhanced in-plane dielectric constant (ε∥) reaching values of about 120 for channels with height 8 Å < h < 10 Å. With the increase in the width of the channel, we predict that ε∥ decreases nonlinearly and reaches the bulk value for h > 70 Å. A stratified continuum model is proposed that reproduces the h > 10 Å dependence of ε∥. For sub-nanometer height channels, abnormal behavior of ε∥ is found with two orders of magnitude reduction of ε∥ around h ∼ 7.5 Å, which is attributed to the formation of a particular ice phase that exhibits long-time (∼μs) stable ferroelectricity. This is of particular importance for the understanding of the influence of confined water on the functioning of biological systems.
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Affiliation(s)
- Ilyar Hamid
- Department of Physics, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Hossein Jalali
- Department of Physics, University of Zanjan, 45195-313 Zanjan, Iran
| | - Francois M Peeters
- Department of Physics, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Mehdi Neek-Amal
- Department of Physics, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
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Hou D, Zhang S, Chen X, Song R, Zhang D, Yao A, Sun J, Wang W, Sun L, Chen B, Liu Z, Wang L. Decimeter-Scale Atomically Thin Graphene Membranes for Gas-Liquid Separation. ACS APPLIED MATERIALS & INTERFACES 2021; 13:10328-10335. [PMID: 33599473 DOI: 10.1021/acsami.0c23013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Graphene holds great potential for fabricating ultrathin selective membranes possessing high permeability without compromising selectivity and has attracted intensive interest in developing high-performance separation membranes for desalination, natural gas purification, hemodialysis, distillation, and other gas-liquid separation. However, the scalable and cost-effective synthesis of nanoporous graphene membranes, especially designing a method to produce an appropriate porous polymer substrate, remains very challenging. Here, we report a facile route to fabricate decimeter-scale (∼15 × 10 cm2) nanoporous atomically thin membranes (NATMs) via the direct casting of the porous polymer substrate onto graphene, which was produced by chemical vapor deposition (CVD). After the vapor-induced phase-inversion process under proper experimental conditions (60 °C and 60% humidity), the flexible nanoporous polymer substrate was formed. The resultant skin-free polymer substrate, which had the proper pore size and a uniform spongelike structure, provided enough mechanical support without reducing the permeance of the NATMs. It was demonstrated that after creating nanopores by the O2 plasma treatment, the NATMs were salt-resistant and simultaneously showed 3-5 times higher gas (CO2) permeance than the state-of-the-art commercial polymeric membranes. Therefore, our work provides guidance for the technological developments of graphene-based membranes and bridges the gap between the laboratory-scale "proof-of-concept" and the practical applications of NATMs in the industry.
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Affiliation(s)
- Dandan Hou
- Institute of microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Beijing Graphene Institute, Beijing 100095, China
| | - Shengping Zhang
- Institute of microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing 100871, China
- Beijing Graphene Institute, Beijing 100095, China
| | - Xiaobo Chen
- Institute of microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Ruiyang Song
- Institute of microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
| | - Dongxu Zhang
- Beijing Graphene Institute, Beijing 100095, China
| | - Ayan Yao
- Beijing Graphene Institute, Beijing 100095, China
| | - Jiayue Sun
- Beijing Graphene Institute, Beijing 100095, China
| | - Wenxuan Wang
- Beijing Graphene Institute, Beijing 100095, China
| | - Luzhao Sun
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing 100871, China
- Beijing Graphene Institute, Beijing 100095, China
| | - Buhang Chen
- Beijing Graphene Institute, Beijing 100095, China
| | - Zhongfan Liu
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing 100871, China
- Beijing Graphene Institute, Beijing 100095, China
| | - Luda Wang
- Institute of microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing 100871, China
- Beijing Graphene Institute, Beijing 100095, China
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32
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Zhou R, Sun C, Bai B. Wall friction should be decoupled from fluid viscosity for the prediction of nanoscale flow. J Chem Phys 2021; 154:074709. [PMID: 33607889 DOI: 10.1063/5.0039228] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The accurate determination of fluid viscosity based on the microscopic information of molecules is very crucial for the prediction of nanoscale flow. Despite the challenge of this problem, researchers have done a lot of meaningful work and developed several distinctive methods. However, one of the common approaches to calculate the fluid viscosity is using the Green-Kubo formula by considering all the fluid molecules in nanospace, inevitably causing the involvement of the frictional interaction between fluid and the wall into the fluid viscosity. This practice is certainly not appropriate because viscosity is essentially related only to the interactions among fluid molecules. Here, we clarify that the wall friction should be decoupled from fluid viscosity by distinguishing the frictional region and the viscous region for the accurate prediction of nanoscale flow. By comparing the fluid viscosities calculated from the Green-Kubo formula in the whole region and viscous region and the viscosity obtained from the velocity profile through the Hagen-Poiseuille equation, it is found that only the calculated viscosity in the viscous region agrees well with the viscosity from the velocity profile. To demonstrate the applicability of this clarification, the Lennard-Jones fluid and water confined between Lennard-Jones, graphene, and silica walls, even with different fluid-wall interactions, are extensively tested. This work clearly defines the viscosity of fluids at nanoscales from the inherent nature of physics, aiming at the accurate prediction of nanoscale flow from the classical continuum hydrodynamic theory.
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Affiliation(s)
- Runfeng Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Bofeng Bai
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
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34
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Zhao Z, Zhou R, Sun C. Hierarchical thermal transport in nanoconfined water. J Chem Phys 2020; 153:234701. [PMID: 33353331 DOI: 10.1063/5.0030738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structure of nanoconfined fluids is particularly non-uniform owing to the wall interaction, resulting in the distinctive characteristic of thermal transport compared to bulk fluids. We present the molecular simulations on the thermal transport of water confined in nanochannels with a major investigation of its spatial distribution under the effects of wall interaction. The results show that the thermal conductivity of nanoconfined water is inhomogeneous and its layered distribution is very similar to the density profile. The layered thermal conductivity is the coupling result of inhomogeneous density and energy distributions that are generally diametrical, and their contributions to the thermal conductivity compensate with each other. However, the accumulative effect of water molecules is really dominating, resulting in a high thermal conductivity in the high-density layers with the low-energy molecules, and vice versa. Moreover, it is found that the adsorptive and repulsive interactions from solid walls have different roles in the hierarchical thermal transport in nanoconfined water. The adsorptive interaction is only responsible for the layered distribution of thermal conductivity, while the repulsive interaction is responsible for the overall thermal conductivity; accordingly, the thermal conductivity is independent of the strength of water-solid interactions. The identified hierarchical thermal transport in nanoconfined water and its underlying mechanisms have a great significance for the understanding of nanoscale thermal transport and even the mass and energy transport of nanoconfined fluids.
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Affiliation(s)
- Zhixiang Zhao
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, China
| | - Runfeng Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
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Paniagua-Guerra LE, Gonzalez-Valle CU, Ramos-Alvarado B. Effects of the Interfacial Modeling Approach on Equilibrium Calculations of Slip Length for Nanoconfined Water in Carbon Slits. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14772-14781. [PMID: 33215929 DOI: 10.1021/acs.langmuir.0c02718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this investigation, equilibrium molecular dynamics simulations were conducted to assess the influence of the interface modeling approach on the calculation of hydrodynamic slip in carbon nanochannels. A Green-Kubo formalism was implemented for the calculation of the slip length in water confined by graphite layers. The nonbonded interactions between solid and liquid atoms (interface models) were modeled using parameters optimized to represent the wetting behavior and adsorption energy curves from electronic structure calculations. Conventional carbon-oxygen-only interaction models were compared against comprehensive models able to represent the molecular-orientation-dependent energy of interaction. Quasi-universal relationships built under the premise of the slip length dependence on the water-graphite affinity and characterized by macroscopic wettability were critically assessed. It was found that the wetting behavior cannot fully characterize the hydrodynamic slip because interface models that produced the same surface wettability yielded different values of the friction coefficient. Alternatively, the density depletion length, used to characterize the interfacial liquid structuring and the availability of momentum carriers (interfacial water molecules), was able to accurately represent the slip length trends independently of the interface model. These findings reassert the importance of physically sound interface models to study interfacial transport properties and the need of reliable parameters and characterization procedures to support theoretical models that seek to unveil the inconsistencies in hydrodynamic slip calculations.
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Affiliation(s)
- Luis E Paniagua-Guerra
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - C Ulises Gonzalez-Valle
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Bladimir Ramos-Alvarado
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Li J, Long R, Zhang B, Yang R, Liu W, Liu Z. Nano Heat Pump Based on Reverse Thermo-osmosis Effect. J Phys Chem Lett 2020; 11:9856-9861. [PMID: 32991184 DOI: 10.1021/acs.jpclett.0c02475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Heat pumps are widely used in domestic applications, agriculture, and industry. Here, we report a novel heat pump based on the reverse thermo-osmosis (RTO) effect in a nanoporous graphene (NPG) membrane. Through classical molecular dynamics (MD) simulation, we prove that the heat pump can transport mass and heat efficiently. The heat and mass fluxes are increased linearly with the hydraulic pressure provided. Ultrahigh heat fluxes of 6.2 ± 1.0 kW/cm2 and coefficient of performance (COP) of 20.2 are obtained with a temperature increment of 5 K and a working pressure of 80 MPa. It is interesting that water molecules on the NPG membrane can evaporate in a cluster state, and the cluster evaporations reduce the vaporization enthalpy of the processes.
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Affiliation(s)
- Ji Li
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Rui Long
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Bo Zhang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ronggui Yang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Wei Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhichun Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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Jia Y, Lu X, Cao Z, Yan T. From a bulk to nanoconfined water chain: bridge water at the pore of the (6,6) carbon nanotube. Phys Chem Chem Phys 2020; 22:25747-25759. [PMID: 33146653 DOI: 10.1039/d0cp02531c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrophobic porous materials with nano-pores are critical in many processes such as water desalination and biological membrane transportation. Herein, we performed molecular dynamics (MD) simulations on a prototypical hydrophobic nanochannel consisting of a (6,6) carbon nanotube (CNT) of 4.12 Å in radius and 13.72 Å in length immersed in water. The simulation shows that there are two major filling numbers of water N = 5 and N = 6, with the former being the most stable one. The confined waters form a single-file water chain with two hydrogen bonds per water. An extending water chain is formed for N = 5, with a bridge water near the pore of the CNT linking the water confined inside the CNT and hydration layer around the pore of the CNT. The bridge water can be considered as intermediate water characterized by three hydrogen bonds that distinguish from the confined water and bulk water. On the other hand, the hydration layer is depleted from the pore when N = 6. The analyses of the correlation of the bond order for the adjacent hydrogen bond pair of the hydration layer around the pore of the CNT does not show apparent difference from that of bulk water, though the former is slightly ordered. van Hove analysis of the bridge water shows that it tends to move inside the CNT when N < 5, in order to maintain the chemical equilibrium between the confined water and bulk water. This study highlights the unique structure of water around the hydrophobic pore of a sub-nanometer nanochannel.
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Affiliation(s)
- Yunzhe Jia
- Institute of New Energy Material Chemistry, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China.
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Meconi GM, Zangi R. Adsorption-induced clustering of CO 2 on graphene. Phys Chem Chem Phys 2020; 22:21031-21041. [PMID: 32926038 DOI: 10.1039/d0cp03482g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Utilization of graphene-based materials for selective carbon dioxide capture has been demonstrated recently as a promising technological approach. In this study we report results from density functional theory calculations and molecular dynamics simulations on the adsorption of CO2, N2, and CH4 gases on a graphene sheet. We calculate adsorption isotherms of ternary and binary mixtures of these gases and reproduce the larger selectivity of CO2 to graphene relative to the other two gases. Furthermore it is shown that the confinement to two-dimensions, associated with adsorbing the CO2 gas molecules on the plane of graphene, increases their propensity to form clusters on the surface. Above a critical surface coverage (or partial pressure) of the gas, these CO2-CO2 interactions augment the effective adsorption energy to graphene, and, in part, contribute to the high selectivity of carbon dioxide with respect to nitrogen and methane. The origin of the attractive interaction between the CO2 molecules adsorbed on the surface is of electric quadrupole-quadrupole nature, in which the positively-charged carbon of one molecule interacts with the negatively-charged oxygen of another molecule. The energy of attraction of forming a CO2 dimer is predicted to be around 5-6 kJ mol-1, much higher than the corresponding values calculated for N2 and CH4. We also evaluated the adsorption energies of these gases to a graphene sheet and found that the attractions obtained using the classical force-fields might be over-exaggerated. Nevertheless, even when the magnitudes of these (classical force-field) graphene-gas interactions are scaled-down sufficiently, the tendency of CO2 molecules to cluster on the surface is still observed.
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Affiliation(s)
- Giulia Magi Meconi
- POLYMAT & Department of Applied Chemistry, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018, San Sebastian, Spain
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