1
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Ikeda T, Kobayashi Y, Yamakawa M. Structure and dynamics of amphiphilic patchy cubes in a nanoslit under shear. J Chem Phys 2024; 161:024901. [PMID: 38973760 DOI: 10.1063/5.0216550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/17/2024] [Indexed: 07/09/2024] Open
Abstract
Patchy nanocubes are intriguing materials with simple shapes and space-filling and multidirectional bonding properties. Previous studies have revealed various mesoscopic structures such as colloidal crystals in the solid regime and rod-like or fractal-like aggregates in the liquid regime of the phase diagram. Recent studies have also shown that mesoscopic structural properties, such as an average cluster size M and orientational order, in amphiphilic nanocube suspensions are associated with macroscopic viscosity changes, mainly owing to differences in cluster shape among patch arrangements. Although many studies have been conducted on the self-assembled structures of nanocubes in bulk, little is known about their self-assembly in nanoscale spaces or structural changes under shear. In this study, we investigated mixtures of one- and two-patch amphiphilic nanocubes confined in two flat parallel plates at rest and under shear using molecular dynamics simulations coupled with multiparticle collision dynamics. We considered two different patch arrangements for the two-patch particles and two different slit widths H to determine the degree of confinement in constant volume fractions in the liquid regime of the phase diagram. We revealed two unique cluster morphologies that have not been previously observed under bulk conditions. At rest, the size of the rod-like aggregates increased with decreasing H, whereas that of the fractal-like aggregates remained constant. Under weak shear with strong confinement, the rod-like aggregates maintained a larger M than the fractal-like aggregates, which were more rigid and maintained a larger M than the rod-like aggregates under bulk conditions.
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Affiliation(s)
- Takahiro Ikeda
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yusei Kobayashi
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Masashi Yamakawa
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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2
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Li J, Zhu C, Zhao W, Gao Y, Bai J, Jiang J, Zeng XC. Formation of a two-dimensional helical square tube ice in hydrophobic nanoslit using the TIP5P water model. J Chem Phys 2024; 160:164716. [PMID: 38661200 DOI: 10.1063/5.0205343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/09/2024] [Indexed: 04/26/2024] Open
Abstract
In extreme and nanoconfinement conditions, the tetrahedral arrangement of water molecules is challenged, resulting in a rich and new phase behavior unseen in bulk phases. The unique phase behavior of water confined in hydrophobic nanoslits has been previously observed, such as the formation of a variety of two-dimensional (2D) ices below the freezing temperature. The primary identified 2D ice phase, termed square tube ice (STI), represents a unique arrangement of water molecules in 2D ice, which can be viewed as an array of 1D ice nanotubes stacked in the direction parallel to the confinement plane. In this study, we report the molecular dynamics (MD) simulations evidence of a novel 2D ice phase, namely, helical square tube ice (H-STI). H-STI is characterized by the stacking of helical ice nanotubes in the direction parallel to the confinement plane. Its structural specificity is evident in the presence of helical square ice nanotubes, a configuration unseen in both STI and single-walled ice nanotubes. A detailed analysis of the hydrogen bonding strength showed that H-STI is a 2D ice phase diverging from the Bernal-Fowler-Pauling ice rules by forming only two strong hydrogen bonds between adjacent molecules along its helical ice chain. This arrangement of strong hydrogen bonds along ice nanotube and weak bonds between the ice nanotube shows a similarity to quasi-one-dimensional van der Waals materials. Ab initio molecular dynamics simulations (over a 30 ps) were employed to further verify H-STI's stability at 1 GPa and temperature up to 200 K.
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Affiliation(s)
- Jiaxian Li
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| | - Chongqin Zhu
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100190, People's Republic of China
| | - Wenhui Zhao
- Department of Physics, School of Physical Science and Technology, Ningbo University, 818 Fenghua Road, Ningbo 315211, People's Republic of China
| | - Yurui Gao
- Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Jaeil Bai
- Department of Physics, University of Nebraska-Omaha, Omaha, Nebraska 68182, USA
| | - Jian Jiang
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong 999077, People's Republic of China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, People's Republic of China
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong 999077, People's Republic of China
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3
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Wei L, Li X, Bai Q, Kang J, Song J, Zhu S, Shen L, Wang H, Zhu C, Fang W. The performance of OPC and OPC3 water models in predictions of 2D structures under nanoconfinement. J Chem Phys 2024; 160:164504. [PMID: 38661199 DOI: 10.1063/5.0202518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
Nanoconfined water plays an important role in broad fields of science and engineering. Classical molecular dynamics (MD) simulations have been widely used to investigate water phases under nanoconfinement. The key ingredient of MD is the force field. In this study, we systematically investigated the performance of a recently introduced family of globally optimal water models, OPC and OPC3, and TIP4P/2005 in describing nanoconfined two-dimensional (2D) water ice. Our studies show that the melting points of the monolayer square ice (MSI) of all three water models are higher than the melting points of the corresponding bulk ice Ih. Under the same conditions, the melting points of MSI of OPC and TIP4P/2005 are the same and are ∼90 K lower than that of the OPC3 water model. In addition, we show that OPC and TIP4P/2005 water models are able to form a bilayer AA-stacked structure and a trilayer AAA-stacked structure, which are not the cases for the OPC3 model. Considering the available experimental data and first-principles simulations, we consider the OPC water model as a potential water model for 2D water ice MD studies.
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Affiliation(s)
- Laiyang Wei
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Xiaojiao Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Qi Bai
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Jing Kang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Jueying Song
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Shuang Zhu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Lin Shen
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Huan Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Chongqin Zhu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
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4
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Wu Y, Wang Z, Li S, Su J. Terahertz electric field induced melting and transport of monolayer water confined in double-walled carbon nanotubes. Phys Chem Chem Phys 2024; 26:10919-10931. [PMID: 38525864 DOI: 10.1039/d4cp00007b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Understanding the structures and dynamics of confined water in nanochannels holds great promise for various applications, ranging from membrane separation to blue energy collection. A setting of particular interest is the confined monolayer water within double-walled carbon nanotubes (DWCNTs), which demonstrates rich ice morphologies; however, the dynamics of this peculiar system are still unexplored. In this work, a series of molecular dynamics (MD) simulations reveal that the two-dimensional ice in DWCNTs can be effectively melted by terahertz electric fields but not by static electric fields, exhibiting an interesting ice to vapor-like transition along with extraordinary dynamical behaviors. Specifically, under appropriate field frequency, the water flow presents a sharp increase with the increase in field strength, indicating an excellent gating behavior. These remarkable findings are attributed to the resonance effect between the terahertz electric field and inherent vibration of water hydrogen bonds, causing the water molecules to change from the frozen to super permeation states. The amount of confined water exhibits a sudden reduction, confirming the breakdown of the hydrogen bond network. The distributions of density profiles, hydrogen bond number and dipole orientation demonstrate more details of the water structural change. Furthermore, under a certain field strength, the water flow shows a peculiar maximum behavior with the increase in field frequency, implying frequency optimization for water transport. These findings not only enhance our understanding of the phase transition behavior of water molecules confined within DWCNTs under the influence of a terahertz electric field but also provide a promising avenue for designing innovative nanofluidic devices.
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Affiliation(s)
- Yue Wu
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, and Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Zi Wang
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, and Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Shuang Li
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, and Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Jiaye Su
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, and Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
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5
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Zhong S, Shi Z, Zhang B, Wen Z, Chen L. Homogeneous water vapor condensation with a deep neural network potential model. J Chem Phys 2024; 160:124303. [PMID: 38516980 DOI: 10.1063/5.0189448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/03/2024] [Indexed: 03/23/2024] Open
Abstract
Molecular-level nucleation has not been clearly understood due to the complexity of multi-body potentials and the stochastic, rare nature of the process. This work utilizes molecular dynamics (MD) simulations, incorporating a first-principles-based deep neural network (DNN) potential model, to investigate homogeneous water vapor condensation. The nucleation rates and critical nucleus sizes predicted by the DNN model are compared against commonly used semi-empirical models, namely extended simple point charge (SPC/E), TIP4P, and OPC, in addition to classical nucleation theory (CNT). The nucleation rates from the DNN model are comparable with those from the OPC model yet surpass the rates from the SPC/E and TIP4P models, a discrepancy that could mainly arise from the overestimated bulk free energy by SPC/E and TIP4P. The surface free energy predicted by CNT is lower than that in MD simulations, while its bulk free energy is higher than that in MD simulations, irrespective of the potential model used. Further analysis of cluster properties with the DNN model unveils pronounced variations of O-H bond length and H-O-H bond angle, along with averaged bond lengths and angles that are enlarged during embryonic cluster formation. Properties such as cluster surface free energy and liquid-to-vapor density transition profiles exhibit significant deviations from CNT assumptions.
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Affiliation(s)
- Shenghui Zhong
- International Innovation Institute, Beihang University, Hangzhou 311115, China
| | - Zheyu Shi
- International Innovation Institute, Beihang University, Hangzhou 311115, China
- College of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Bin Zhang
- International Innovation Institute, Beihang University, Hangzhou 311115, China
| | - Zhengcheng Wen
- College of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Longfei Chen
- International Innovation Institute, Beihang University, Hangzhou 311115, China
- School of Energy and Power Engineering, Beihang University, Beijing 100191, China
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6
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Dufils T, Schran C, Chen J, Geim AK, Fumagalli L, Michaelides A. Origin of dielectric polarization suppression in confined water from first principles. Chem Sci 2024; 15:516-527. [PMID: 38179530 PMCID: PMC10763014 DOI: 10.1039/d3sc04740g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/23/2023] [Indexed: 01/06/2024] Open
Abstract
It has long been known that the dielectric constant of confined water should be different from that in bulk. Recent experiments have shown that it is vanishingly small, however the origin of the phenomenon remains unclear. Here we used ab initio molecular dynamics simulations (AIMD) and AIMD-trained machine-learning potentials to understand water's structure and electronic properties underpinning this effect. For the graphene and hexagonal boron-nitride substrates considered, we find that it originates in the spontaneous anti-parallel alignment of the water dipoles in the first two water layers near the solid interface. The interfacial layers exhibit net ferroelectric ordering, resulting in an overall anti-ferroelectric arrangement of confined water. Together with constrained hydrogen-bonding orientations, this leads to much reduced out-of-plane polarization. Furthermore, we directly contrast AIMD and simple classical force-field simulations, revealing important differences. This work offers insight into a property of water that is critical in modulating surface forces, the electric-double-layer formation and molecular solvation, and shows a way to compute it.
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Affiliation(s)
- T Dufils
- Department of Physics and Astronomy, University of Manchester Manchester M13 9PL UK
- National Graphene Institute, University of Manchester Manchester M13 9PL UK
| | - C Schran
- Cavendish Laboratory, Department of Physics, University of Cambridge Cambridge CB3 0HE UK
- Lennard-Jones Centre, University of Cambridge Trinity Ln Cambridge CB2 1TN UK
| | - J Chen
- School of Physics, Peking University Beijing 100871 China
| | - A K Geim
- Department of Physics and Astronomy, University of Manchester Manchester M13 9PL UK
- National Graphene Institute, University of Manchester Manchester M13 9PL UK
| | - L Fumagalli
- Department of Physics and Astronomy, University of Manchester Manchester M13 9PL UK
- National Graphene Institute, University of Manchester Manchester M13 9PL UK
| | - A Michaelides
- Lennard-Jones Centre, University of Cambridge Trinity Ln Cambridge CB2 1TN UK
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
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7
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Shi Y, Limbu DK, Zhang Z, Momeni MR, Shakib FA. Effects of Defects and Presence of Open-Metal Sites on the Structure and Dynamics of Water in Hydrophobic Zeolitic Imidazolate Frameworks. J Chem Inf Model 2023; 63:7097-7106. [PMID: 37811792 DOI: 10.1021/acs.jcim.3c01077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Most of the chemistry in nanoporous materials with small pore sizes and windows takes place on the outer surface, which is in direct contact with the substrate/solvent, rather than within the pores and channels. Here, we report the results of our comprehensive atomistic molecular dynamics (MD) simulations to decipher the interaction of water with a realistic finite ∼5.1 nm nanoparticle (NP) model of ZIF-8, with edges containing undercoordinated Zn metal sites, vs a conventionally employed pristine crystalline bulk (CB) model. The hydrophobic interior surface of the CB model imparts significant dynamical behavior on water molecules with (i) increasing diffusivity from the surface toward the center of the pores and (ii) confined water, at low concentration, showing similar diffusivity to that of the bulk water. On the other hand, water molecules adsorbed on the surface of the NP model exhibit a range of characteristics, including "coordinated", "confined", and "bulk-like" behavior. Some of the water molecules form coordinative bonds with the undercoordinated Zn metal centers and act as nucleation sites for the water droplets to form, facilitating diffusion into the pores. However, diffusion of water molecules is limited to the areas near the surface and not all the way to the core of the NP model. Our atomistic MD simulations provide insights into the stability of ZIFs in aqueous solutions despite hydrolysis of their outer surface. Such insights are helpful in designing more robust nanoporous materials for applications in humid environments.
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Affiliation(s)
- Yuliang Shi
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Dil K Limbu
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Zeyu Zhang
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Mohammad R Momeni
- Division of Energy, Matter and Systems, School of Science and Engineering, University of Missouri─Kansas City, Kansas City, Missouri 64110, United States
| | - Farnaz A Shakib
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
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8
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Wei L, Bai Q, Li X, Liu Z, Li C, Cui Y, Shen L, Zhu C, Fang W. Puckered Zigzag Monolayer Ice: Does a Confined Flat Four-Coordinated Monolayer Ice Always Have a Corresponding Puckered Phase? J Phys Chem Lett 2023; 14:8890-8895. [PMID: 37767947 DOI: 10.1021/acs.jpclett.3c02065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
We note that a flat, four-coordinated monolayer ice under confinement always has a corresponding puckered phase. Recently, a monolayer ice consisting of an array of zigzag water chains (ZZMI) predicted by first-principles calculations of water under confinement is a flat four-coordinated monolayer ice. Herein, to investigate whether puckered ZZMI exists stably, we perform molecular dynamics simulations of two-dimensional (2D) ice formation for water constrained in graphene nanocapillaries. We find a novel monolayer ice structure that can be viewed as the ZZMI puckered along the direction perpendicular to the zigzag chain (pZZMI). Unlike ZZMI that does not satisfy the ice rule, each water molecule in pZZMI can form four hydrogen bonds (HBs) via forming two stable intersublayer HBs and two intrasublayer HBs. This work provides a fresh perspective on 2D confined ice, highlighting the intrinsic connections between 2D confined ices.
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Affiliation(s)
- Laiyang Wei
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Qi Bai
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Xiaojiao Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Ziyuan Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Chenruyuan Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Yanhong Cui
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310023, People's Republic of China
| | - Lin Shen
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Chongqin Zhu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
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Lin B, Jiang J, Zeng XC, Li L. Temperature-pressure phase diagram of confined monolayer water/ice at first-principles accuracy with a machine-learning force field. Nat Commun 2023; 14:4110. [PMID: 37433823 DOI: 10.1038/s41467-023-39829-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 06/23/2023] [Indexed: 07/13/2023] Open
Abstract
Understanding the phase behaviour of nanoconfined water films is of fundamental importance in broad fields of science and engineering. However, the phase behaviour of the thinnest water film - monolayer water - is still incompletely known. Here, we developed a machine-learning force field (MLFF) at first-principles accuracy to determine the phase diagram of monolayer water/ice in nanoconfinement with hydrophobic walls. We observed the spontaneous formation of two previously unreported high-density ices, namely, zigzag quasi-bilayer ice (ZZ-qBI) and branched-zigzag quasi-bilayer ice (bZZ-qBI). Unlike conventional bilayer ices, few inter-layer hydrogen bonds were observed in both quasi-bilayer ices. Notably, the bZZ-qBI entails a unique hydrogen-bonding network that consists of two distinctive types of hydrogen bonds. Moreover, we identified, for the first time, the stable region for the lowest-density [Formula: see text] monolayer ice (LD-48MI) at negative pressures (<-0.3 GPa). Overall, the MLFF enables large-scale first-principle-level molecular dynamics (MD) simulations of the spontaneous transition from the liquid water to a plethora of monolayer ices, including hexagonal, pentagonal, square, zigzag (ZZMI), and hexatic monolayer ices. These findings will enrich our understanding of the phase behaviour of the nanoconfined water/ices and provide a guide for future experimental realization of the 2D ices.
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Affiliation(s)
- Bo Lin
- Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Jian Jiang
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, 999077, Hong Kong
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Xiao Cheng Zeng
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, 999077, Hong Kong.
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
| | - Lei Li
- Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
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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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11
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Ma N, Zhao X, Liang X, Zhu W, Sun Y, Zhao W, Zeng XC. Continuous and First-Order Liquid–Solid Phase Transitions in Two-Dimensional Water. J Phys Chem B 2022; 126:8892-8899. [DOI: 10.1021/acs.jpcb.2c05618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nan Ma
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiaorong Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiaoying Liang
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Weiduo Zhu
- Department of Physics, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Yunxiang Sun
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Wenhui Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiao Cheng Zeng
- Department of Materials Science & Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong, China
- Department of Chemistry, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States
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12
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The first-principles phase diagram of monolayer nanoconfined water. Nature 2022; 609:512-516. [PMID: 36104556 DOI: 10.1038/s41586-022-05036-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 06/28/2022] [Indexed: 11/09/2022]
Abstract
Water in nanoscale cavities is ubiquitous and of central importance to everyday phenomena in geology and biology. However, the properties of nanoscale water can be substantially different from those of bulk water, as shown, for example, by the anomalously low dielectric constant of water in nanochannels1, near frictionless water flow2 or the possible existence of a square ice phase3. Such properties suggest that nanoconfined water could be engineered for technological applications in nanofluidics4, electrolyte materials5 and water desalination6. Unfortunately, challenges in experimentally characterizing water at the nanoscale and the high cost of first-principles simulations have prevented the molecular-level understanding required to control the behaviour of water. Here we combine a range of computational approaches to enable a first-principles-level investigation of a single layer of water within a graphene-like channel. We find that monolayer water exhibits surprisingly rich and diverse phase behaviour that is highly sensitive to temperature and the van der Waals pressure acting within the nanochannel. In addition to multiple molecular phases with melting temperatures varying non-monotonically by more than 400 kelvins with pressure, we predict a hexatic phase, which is an intermediate between a solid and a liquid, and a superionic phase with a high electrical conductivity exceeding that of battery materials. Notably, this suggests that nanoconfinement could be a promising route towards superionic behaviour under easily accessible conditions.
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13
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Kobayashi Y, Arai N, Yasuoka K. Correlation between ordering and shear thinning in confined OMCTS liquids. J Chem Phys 2022; 157:114506. [DOI: 10.1063/5.0099473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Despite the extensive research that has been conducted for decades on the behavior of confined liquids, detailed knowledge of this phenomenon, particularly in the mixed/boundary lubrication regime, remains limited. This can be attributed to several factors including the difficulty of direct experimental observations of the behavior of lubricant molecules under non-equilibrium conditions, the high computational cost of molecular simulations to reach steady state, and the low signal-to-noise ratio at extremely low shear rates corresponding to actual operating conditions. To this end, we studied the correlation between the structure formation and shear viscosity of octamethylcyclotetrasiloxane confined between two mica surfaces in a mixed/boundary lubrication regime. Three different surface separations corresponding to two-, three-, and five-layered structures were considered to analyze the effect of confinement. The orientational distributions with one specific peak for n=2 and two distributions, including a parallel orientation with the surface normal for n>2, were observed at rest. The confined liquids exhibited a distinct shear-thinning behavior independent of surface separations for a relatively low shear rate, \dot{\gamma}<10^{8} s^{-1}. However, the shear viscosities at \dot{\gamma}<10^{8} s^{-1} depended on the number of layered structures. Newtonian behavior was observed with a further increase in the shear rate. Furthermore, we found a strong correlation between the degree of molecular orientation and the shear viscosity of the confined liquids. The magnitude of the shear viscosity of the confined liquids can primarily be determined by the degree of molecular orientation, and shear-thinning originates from the vanishing of specific orientational distributions with increasing shear rate.
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Affiliation(s)
- Yusei Kobayashi
- Mechanical Engineering, Keio University Faculty of Science and Technology Department of Mechanical Engineering, Japan
| | - Noriyoshi Arai
- Keio University Faculty of Science and Technology Department of Mechanical Engineering, Japan
| | - Kenji Yasuoka
- Mechanical Engineering, Keio University - Yagami Campus, Japan
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Kwan V, Maiti SR, Saika-Voivod I, Consta S. Salt Enrichment and Dynamics in the Interface of Supercooled Aqueous Droplets. J Am Chem Soc 2022; 144:11148-11158. [PMID: 35715222 DOI: 10.1021/jacs.2c01159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interconversion reaction of NaCl between the contact-ion pair (CIP) and the solvent-separated ion pair (SSIP) as well as the free-ion state in cold droplets has not yet been investigated. We report direct computational evidence that the lower is the temperature, the closer to the surface the ion interconversion reaction takes place. In supercooled droplets the enrichment of the subsurface in salt becomes more evident. The stability of the SSIP relative to the CIP increases as the ion-pairing is transferred toward the droplet's outer layers. In the free-ion state, where the ions diffuse independently in the solution, the number density of Cl- shows a broad maximum in the interior in addition to the well-known maximum in the surface. In the study of the reaction dynamics, we find a weak coupling between the interionic NaCl distance reaction coordinate and the solvent degrees of freedom, which contrasts with the diffusive crossing of the free energy barrier found in bulk solution modeling. The H2O self-diffusion coefficient is found to be at least an order of magnitude larger than that in the bulk solution. We propose to exploit the enhanced surface ion concentration at low temperature to eliminate salts from droplets in native mass spectrometry ionization methods.
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Affiliation(s)
- Victor Kwan
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Shoubhik R Maiti
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.,Department of Chemistry, The University of Sheffield, Sheffield S3 7HF, United Kingdom
| | - Ivan Saika-Voivod
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's A1B 3X7, Canada
| | - Styliani Consta
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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Fang F, Fu S, Lin J, Zhu J, Dai Z, Zhou G, Yang Z. Molecular-Level Insights into Unique Behavior of Water Molecules Confined in the Heterojunction between One- and Two-Dimensional Nanochannels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7300-7311. [PMID: 35635722 DOI: 10.1021/acs.langmuir.2c00825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
With the increasing importance of nanoconfined water in various heterostructures, it is quite essential to clarify the influence of nanoconfinement on the unique properties of water molecules in the pivotal heterojunction. In this work, we reported a series of classical molecular dynamics (MD) simulations to explore nanoconfined water in the subnanometer-sized and nanometer-sized heterostructures by adjusting one-dimensional (1-D) carbon nanotubes with different diameters and two-dimensional (2-D) graphene sheets with different interlayer distances. Our simulation results demonstrated that water molecules in the 1-D/2-D heterojunction show an obvious structural rearrangement associated with the remarkable breaking and formation of hydrogen bonds (HBs), and such rearrangements in the subnanometer-sized systems are much more pronounced than those in the nanometer-sized ones. When water molecules in the 1-D/2-D heterojunctions migrate from 2-D to 1-D confinements, the ordered multi-layer structure in the 2-D confinement are completely destroyed and then transform into different circular HB networks near the nanotube orifice for better connecting to the single-file or helical HB network in the 1-D nanotubes. Furthermore, water molecules in the 1-D/2-D heterojunctions can form stronger HBs with those water molecules further away from the 1-D confinement, leading to an asymmetrical orientational distribution near the orifice. More importantly, our comparison results revealed that the 1-D confinement plays a more important role than the 2-D confinement in determining both the structures and dynamics of water molecules in the 1-D/2-D heterojunction.
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Affiliation(s)
- Fang Fang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Shan Fu
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Jie Lin
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Jia Zhu
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Zhongyang Dai
- National Supercomputing Center in Shenzhen, Shenzhen 518055, People's Republic of China
| | - Guobing Zhou
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Zhen Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
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Zhao X, Liu Y, Lin D, Zhu W, Ma N, Xu WW, Zhao W, Sun Y, Zeng XC. Anomalous Phase Behaviors of Monolayer NaCl Aqueous Solutions Induced by Effective Coulombic Interactions within Angstrom-Scale Slits. J Phys Chem Lett 2022; 13:2704-2710. [PMID: 35302778 DOI: 10.1021/acs.jpclett.2c00501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Interests in subnanofluidic devices have called for molecular dynamics (MD) simulation studies of the thermodynamic behavior of monolayer salt solution within angstrom-scale slits. However, it still remains a grand challenge to accurately describe the Coulombic interactions by incorporating the effects of charge transfer and electronic dielectric screening. Herein, by using the electronic continuum model, where the effective ion charges are fine-tuned with a scaling factor of λ, we present simulation evidence that the effective Coulombic interactions among Na+/Cl- ions can strongly affect the behavior of monolayer ionic aqueous solution. Our microsecond-scale MD simulations show that only the counterions with moderate effective charges (0.3 ≤ λ ≤ 0.8) can dissolve in monolayer water, whereas the high effective charges (λ ≥ 0.85) induce ions to assemble into monolayer nanocrystals, and ions with the low effective charges (λ ≤ 0.2) exhibit gas-like nanobubble. These findings could provide deeper insights into the physical chemistry behind subnanofluidic iontronic devices.
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Affiliation(s)
- Xiaorong Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Yuying Liu
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Dongdong Lin
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Weiduo Zhu
- Department of Physics, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Nan Ma
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Wen Wu Xu
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Wenhui Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Yunxiang Sun
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States
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Williams CD, Wei Z, Shaharudin MRB, Carbone P. A molecular simulation study into the stability of hydrated graphene nanochannels used in nanofluidics devices. NANOSCALE 2022; 14:3467-3479. [PMID: 35170614 DOI: 10.1039/d1nr08275b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Graphene-based nanochannels are a popular choice in emerging nanofluidics applications because of their tunable and nanometer-scale channels. In this work, molecular dynamics (MD) simulations were employed both to (i) assess the stability of dry and hydrated graphene nanochannels and (ii) elucidate the properties of water confined in these channels, using replica-scale models with 0.66-2.38 nm channel heights. The use of flexible nanochannel walls allows the nanochannel height to relax in response to the solvation forces arising from the confined fluid and the forces between the confining surfaces, without the need for application of arbitrarily high external pressures. Dry nanochannels were found to completely collapse if the initial nanochannel height was less than 2 nm, due to attractive van der Waals interactions between the confining graphene surfaces. However, the presence of water was found to prevent total nanochannel collapse, due to repulsive hydration forces opposing the attractive van der Waals force. For nanochannel heights less than ∼1.7 nm, the confining surfaces must be relaxed to obtain accurate hydration pressures and water diffusion coefficients, by ensuring commensurability between the number of confined water layers and the channel height. For very small (∼0.7 nm), hydrated channels a pressure of 231 MPa due to the van der Waals forces was obtained. In the same system, the confined water forms a mobile, liquid monolayer with a diffusion coefficient of 4.0 × 10-5 cm2 s-1, much higher than bulk liquid water. Although this finding conflicts with most classical MD simulations, which predict in-plane order and arrested dynamics, it is supported by experiments and recently published first-principles MD simulations. Classical simulations can therefore be used to predict the properties of water confined in sub-nanometre graphene channels, providing sufficiently realistic molecular models and accurate intermolecular potentials are employed.
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Affiliation(s)
- Christopher D Williams
- Department of Chemical Engineering and Analytical Science, School of Engineering, The University of Manchester, Manchester, UK.
| | - Zixuan Wei
- Department of Chemical Engineering and Analytical Science, School of Engineering, The University of Manchester, Manchester, UK.
| | - Mohd Rafie Bin Shaharudin
- Department of Chemical Engineering and Analytical Science, School of Engineering, The University of Manchester, Manchester, UK.
| | - Paola Carbone
- Department of Chemical Engineering and Analytical Science, School of Engineering, The University of Manchester, Manchester, UK.
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Jian ZB, Bie J, Chen S. Self-assembled rhomboidal ammonia monolayer confined in two vertically stacked graphene oxide/graphene nanosheets. NANOSCALE 2021; 13:16615-16621. [PMID: 34585703 DOI: 10.1039/d1nr04062f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Confined water molecules have attracted widespread research interest due to their versatile phase behaviors. Ammonia (NH3, isoelectronic with water) molecules are also expected to realize the delicate self-assembled hydrogen-bonded network like water in confinement. Here, the structures and phase behavior of NH3 monolayers confined in two structurally symmetrical graphene oxide (GO) or graphene (G) nanosheets are investigated using first-principles calculations and ab initio molecular dynamics simulations. A highly ordered new rhomboidal phase with all NH3 molecules adopting a Y-shaped configuration, in which one N-H bond is parallel to the confining planes and two other N-H bonds point to the top/bottom GO/G layers, respectively, was discovered at low temperature, resulting from the symmetrical confinement and subtle interlayer/intermolecular interactions. Remarkably, this new phase is so stable that a quite large strain is needed to destroy it. At room temperature, these NH3 monolayers behave like a liquid. These rhomboidal NH3 monolayers confined in GO/G nanosheets not only offer diverse hydrogen-bonded networks but also possess potential piezoelectricity for future device applications.
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Affiliation(s)
- Zhi-Bin Jian
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, Jiangsu 210023, China.
| | - Jie Bie
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, Jiangsu 210023, China.
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Shuang Chen
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, Jiangsu 210023, China.
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Zhao W, Sun Y, Zhu W, Jiang J, Zhao X, Lin D, Xu W, Duan X, Francisco JS, Zeng XC. Two-dimensional monolayer salt nanostructures can spontaneously aggregate rather than dissolve in dilute aqueous solutions. Nat Commun 2021; 12:5602. [PMID: 34556665 PMCID: PMC8460741 DOI: 10.1038/s41467-021-25938-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/02/2021] [Indexed: 11/29/2022] Open
Abstract
It is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal ring and/or zigzag chain patterns. These structural patterns appeared to be quite generic, regardless of the water and ion models used in the MD simulations. The generic patterns formed by 2D monolayer NaCl and LiCl nanostructures were also confirmed by ab initio MD simulations. The formation of 2D salt structures in dilute aqueous solution at room temperature is counterintuitive. Free energy calculations indicated that the unexpected spontaneous salt nucleation behavior can be attributed to the nanoscale confinement and strongly compressed hydration shells of ions. Aqueous solutions under nanoscale confinement exhibit interesting physicochemical properties. This work reports evidence on the spontaneous formation of two-dimensional alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement by computer simulations.
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Affiliation(s)
- Wenhui Zhao
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Yunxiang Sun
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Weiduo Zhu
- Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Jian Jiang
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Xiaorong Zhao
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Dongdong Lin
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Wenwu Xu
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Xiangmei Duan
- Department of Physics, Ningbo University, Ningbo, 315211, China
| | - Joseph S Francisco
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, 19104, USA. .,Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA. .,Department of Chemical & Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
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