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Liu D, Xiong Z, Wang P, Liang Q, Zhu H, Liu JZ, Forsyth M, Li D. Ion-Specific Nanoconfinement Effect in Multilayered Graphene Membranes: A Combined Nuclear Magnetic Resonance and Computational Study. NANO LETTERS 2023. [PMID: 37315026 DOI: 10.1021/acs.nanolett.3c00877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ion adsorption within nanopores is involved in numerous applications. However, a comprehensive understanding of the fundamental relationship between in-pore ion concentration and pore size, particularly in the sub-2 nm range, is scarce. This study investigates the ion-species-dependent concentration in multilayered graphene membranes (MGMs) with tunable nanoslit sizes (0.5-1.6 nm) using nuclear magnetic resonance and computational simulations. For Na+-based electrolytes in MGMs, the concentration of anions in graphene nanoslits increases in correlation with their chaotropic properties. As the nanoslit size decreases, the concentration of chaotropic ion (BF4-) increases, whereas the concentration of kosmotropic ions (Cit3-, PO43-) and other ions (Ac-, F-) decreases or changes slightly. Notably, anions remain more concentrated than counter Na+ ions, leading to electroneutrality breakdown and unipolar anion packing in MGMs. A continuum modeling approach, integrating molecular dynamic simulation with the Poisson-Boltzmann model, elucidates these observations by considering water-mediated ion-graphene non-electrostatic interactions and charge screening from graphene walls.
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Affiliation(s)
- Diyan Liu
- Department of Materials Science and Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Zhiyuan Xiong
- School of Light Industry and Engineering, South China University of Technology, Guangzhou 510640, China
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Peiyao Wang
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
- Department of Mechanical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Qinghua Liang
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Haijin Zhu
- Institute for Frontier Materials, Deakin University, Burwood, VIC 3125, Australia
- Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion-Israel Institute of Technology, Guangdong 515063, P. R. China
| | - Jefferson Zhe Liu
- Department of Mechanical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Maria Forsyth
- Institute for Frontier Materials, Deakin University, Burwood, VIC 3125, Australia
| | - Dan Li
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
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Xue M, Qiu H, Shen C, Zhang Z, Guo W. Ion Hydration under Nanoscale Confinement: Dimensionality and Scale Effects. J Phys Chem Lett 2022; 13:4815-4822. [PMID: 35616271 DOI: 10.1021/acs.jpclett.2c00817] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
How ions are hydrated in nanoconfined spaces is crucial for understanding many natural phenomena and practical applications, such as biological functionalities and energy conversion devices. In real systems, nanoconfinement shows structural diversity, but the influence of dimensionality and scale on ion hydration remains considerably unrevealed. Here, we study ion hydration under various confinements by systematic molecular dynamics simulations. In a given dimension, the structure and dynamics of water molecules in the first hydration shell are altered to a degree inversely correlated with the confinement scale, as long as there is no central bulk-like region. Further comparison of ion hydration among different dimensional systems shows that this scale effect becomes more pronounced in systems with lower dimensionality, due to a more significant water layering effect and lower probability for ions to stay away from confining surfaces. These findings provide a qualitatively new understanding of ion transport in biological channels and are instrumental for the design of functional nanofluidic devices.
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Affiliation(s)
- Minmin Xue
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China
| | - Hu Qiu
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China
| | - Chun Shen
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China
| | - Zhuhua Zhang
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China
| | - Wanlin Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of 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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Zhao X, Qiu H, Zhou W, Guo Y, Guo W. Phase-dependent friction of nanoconfined water meniscus. NANOSCALE 2021; 13:3201-3207. [PMID: 33527966 DOI: 10.1039/d0nr08121c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A water meniscus naturally forms under ambient conditions at the point of contact between a nanoscale tip and an atomically flat substrate. Here, we study the effect of the phase state of this nanoscale meniscus-consisting of coexisting monolayer, bilayer and trilayer phase domains-on the frictional behavior during tip sliding by means of molecular dynamics simulations. While the meniscus experiences a domain-by-domain liquid-to-solid phase transition induced by lateral compression, we observe an evident transition in measured friction curves from continuous sliding to stick-slip and meanwhile a gradual increase in friction forces. Moreover, the stick-slip friction can be modulated by varying lattice orientation of the monolayer ice domain in the meniscus, choosing the sliding direction or applying in-plane strains to the substrate. Our results shed light on the rational design of high-performance micro- and nano-electromechanical systems relying on hydration lubrication.
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Affiliation(s)
- Xin Zhao
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of MOE, Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Hu Qiu
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of MOE, Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Wanqi Zhou
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of MOE, Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Yufeng Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of MOE, Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Wanlin Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory for Intelligent Nano Materials and Devices of MOE, Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
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Qian J, Gao X, Pan B. Nanoconfinement-Mediated Water Treatment: From Fundamental to Application. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8509-8526. [PMID: 32511915 DOI: 10.1021/acs.est.0c01065] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Safe and clean water is of pivotal importance to all living species and the ecosystem on earth. However, the accelerating economy and industrialization of mankind generate water pollutants with much larger quantity and higher complexity than ever before, challenging the efficacy of traditional water treatment technologies. The flourishing researches on nanomaterials and nanotechnologies in the past decade have generated new understandings on many fundamental processes and brought revolutionary upgrades to various traditional technologies in almost all areas, including water treatment. An indispensable step toward the real application of nanomaterials in water treatment is to confine them in large processable substrate to address various inherent issues, such as spontaneous aggregation, difficult operation and potential environmental risks. Strikingly, when the size of the spatial restriction provided by the substrate is on the order of only one or several nanometers, referred to as nanoconfinement, the phase behavior of matter and the energy diagram of a chemical reaction could be utterly changed. Nevertheless, the relationship between such changes under nanoconfinement and their implications for water treatment is rarely elucidated systematically. In this Critical Review, we will briefly summarize the current state-of-the-art of the nanomaterials, as well as the nanoconfined analogues (i.e., nanocomposites) developed for water treatment. Afterward, we will put emphasis on the effects of nanoconfinement from three aspects, that is, on the structure and behavior of water molecules, on the formation (e.g., crystallization) of confined nanomaterials, and on the nanoenabled chemical reactions. For each aspect, we will build the correlation between the nanoconfinement effects and the current studies for water treatment. More importantly, we will make proposals for future studies based on the missing links between some of the nanoconfinement effects and the water treatment technologies. Through this Critical Review, we aim to raise the research attention on using nanoconfinement as a fundamental guide or even tool to advance water treatment technologies.
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Affiliation(s)
- Jieshu Qian
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 China
| | - Xiang Gao
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
| | - Bingcai Pan
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
- State Key Laboratory of Pollution Control and Resources Reuse, Nanjing University, Nanjing 210023 China
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