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Cobeña-Reyes J, Ye T, Martini A. Simulations of Subnanometer Scale Image Contrast in Atomic Force Microscopy of Self-Assembled Monolayers in Water. CHEMICAL & BIOMEDICAL IMAGING 2023; 1:147-156. [PMID: 37235190 PMCID: PMC10208375 DOI: 10.1021/cbmi.3c00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/10/2023] [Accepted: 02/20/2023] [Indexed: 05/28/2023]
Abstract
Achieving high-resolution images using dynamic atomic force microscopy (AFM) requires understanding how chemical and structural features of the surface affect image contrast. This understanding is particularly challenging when imaging samples in water. An initial step is to determine how well-characterized surface features interact with the AFM tip in wet environments. Here, we use molecular dynamics simulations of a model AFM tip apex oscillating in water above self-assembled monolayers (SAMs) with different chain lengths and functional groups. The amplitude response of the tip is characterized across a range of vertical distances and amplitude set points. Then relative image contrast is quantified as the difference of the amplitude response of the tip when it is positioned directly above a SAM functional group vs positioned between two functional groups. Differences in contrast between SAMs with different lengths and functional groups are explained in terms of the vertical deflection of the SAMs due to interactions with the tip and water during dynamic imaging. The knowledge gained from simulations of these simple model systems may ultimately be used to guide selection of imaging parameters for more complex surfaces.
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Affiliation(s)
- José Cobeña-Reyes
- Department
of Mechanical Engineering, University of
California Merced, Merced, California 95343, United States
| | - Tao Ye
- Department
of Chemistry & Biochemistry, University
of California Merced, Merced, California 95343, United States
| | - Ashlie Martini
- Department
of Mechanical Engineering, University of
California Merced, Merced, California 95343, United States
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2
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John S, Kühnle A. Hydration Structure at the Calcite-Water (10.4) Interface in the Presence of Rubidium Chloride. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11691-11698. [PMID: 36120896 DOI: 10.1021/acs.langmuir.2c01745] [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
Solid-liquid interfaces are of significant importance in a multitude of geochemical and technological fields. More specifically, the solvation structure plays a decisive role in the properties of the interfaces. Atomic force microscopy (AFM) has been used to resolve the interfacial hydration structure in the presence and absence of ions. Despite many studies investigating the calcite-water interface, the impact of ions on the hydration structure at this interface has rarely been studied. Here, we investigate the calcite-water interface at various concentrations (ranging from 0 to 5 M) of rubidium chloride (RbCl) using three-dimensional atomic force microscopy (3D AFM). We present molecularly resolved images of the hydration structure at the interface. Interestingly, the characteristic pattern of the hydration structure appears similar regardless of the RbCl concentration. The presence of the ions is detected in an indirect manner by more frequent contrast changes and slice displacements.
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Affiliation(s)
- Simon John
- Physical Chemistry I, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Angelika Kühnle
- Physical Chemistry I, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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3
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Gebauer D, Gale JD, Cölfen H. Crystal Nucleation and Growth of Inorganic Ionic Materials from Aqueous Solution: Selected Recent Developments, and Implications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107735. [PMID: 35678091 DOI: 10.1002/smll.202107735] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/07/2022] [Indexed: 05/27/2023]
Abstract
In this review article, selected, latest theoretical, and experimental developments in the field of nucleation and crystal growth of inorganic materials from aqueous solution are highlighted, with a focus on literature after 2015 and on non-classical pathways. A key point is to emphasize the so far underappreciated role of water and solvent entropy in crystallization at all stages from solution speciation through to the final crystal. While drawing on examples from current inorganic materials where non-classical behavior has been proposed, the potential of these approaches to be adapted to a wide-range of systems is also discussed, while considering the broader implications of the current re-assessment of pathways for crystallization. Various techniques that are suitable for the exploration of crystallization pathways in aqueous solution, from nucleation to crystal growth are summarized, and a flow chart for the assignment of specific theories based on experimental observations is proposed.
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Affiliation(s)
- Denis Gebauer
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167, Hannover, Germany
| | - Julian D Gale
- Curtin Institute for Computation/The Institute for Geoscience Research (TiGER), School of Molecular and Life Sciences, Curtin University, PO Box U1987, Perth, Western Australia, 6845, Australia
| | - Helmut Cölfen
- University of Konstanz, Physical Chemistry, Universitätsstr. 10, 78465, Konstanz, Germany
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4
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Dou Z, Qian J, Li Y, Lin R, Wang J, Cheng P, Xu Z. Reducing molecular simulation time for AFM images based on super-resolution methods. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2021; 12:775-785. [PMID: 34386314 PMCID: PMC8329368 DOI: 10.3762/bjnano.12.61] [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: 04/06/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
Atomic force microscopy (AFM) has been an important tool for nanoscale imaging and characterization with atomic and subatomic resolution. Theoretical investigations are getting highly important for the interpretation of AFM images. Researchers have used molecular simulation to examine the AFM imaging mechanism. With a recent flurry of researches applying machine learning to AFM, AFM images obtained from molecular simulation have also been used as training data. However, the simulation is incredibly time consuming. In this paper, we apply super-resolution methods, including compressed sensing and deep learning methods, to reconstruct simulated images and to reduce simulation time. Several molecular simulation energy maps under different conditions are presented to demonstrate the performance of reconstruction algorithms. Through the analysis of reconstructed results, we find that both presented algorithms could complete the reconstruction with good quality and greatly reduce simulation time. Moreover, the super-resolution methods can be used to speed up the generation of training data and vary simulation resolution for AFM machine learning.
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Affiliation(s)
- Zhipeng Dou
- School of Physics, Beihang University, Beijing 100083, China
| | - Jianqiang Qian
- School of Physics, Beihang University, Beijing 100083, China
| | - Yingzi Li
- School of Physics, Beihang University, Beijing 100083, China
| | - Rui Lin
- School of Physics, Beihang University, Beijing 100083, China
| | - Jianhai Wang
- School of Physics, Beihang University, Beijing 100083, China
| | - Peng Cheng
- School of Physics, Beihang University, Beijing 100083, China
| | - Zeyu Xu
- School of Physics, Beihang University, Beijing 100083, China
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5
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Ranawat YS, Jaques YM, Foster AS. Predicting hydration layers on surfaces using deep learning. NANOSCALE ADVANCES 2021; 3:3447-3453. [PMID: 36133729 PMCID: PMC9419798 DOI: 10.1039/d1na00253h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 05/03/2021] [Indexed: 06/16/2023]
Abstract
Characterisation of the nanoscale interface formed between minerals and water is essential to the understanding of natural processes, such as biomineralization, and to develop new technologies where function is dominated by the mineral-water interface. Atomic force microscopy offers the potential to characterize solid-liquid interfaces in high-resolution, with several experimental and theoretical studies offering molecular scale resolution by linking measurements directly to water density on the surface. However, the theoretical techniques used to interpret such results are computationally intensive and development of the approach has been limited by interpretation challenges. In this work, we develop a deep learning architecture to learn the solid-liquid interface of polymorphs of calcium carbonate, allowing for the rapid predictions of density profiles with reasonable accuracy.
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Affiliation(s)
| | - Ygor M Jaques
- Department of Applied Physics, Aalto University Finland
| | - Adam S Foster
- Department of Applied Physics, Aalto University Finland
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University Kakuma-machi Kanazawa 920-1192 Japan
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6
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Miyazawa K, Tracey J, Reischl B, Spijker P, Foster AS, Rohl AL, Fukuma T. Tip dependence of three-dimensional scanning force microscopy images of calcite-water interfaces investigated by simulation and experiments. NANOSCALE 2020; 12:12856-12868. [PMID: 32520063 DOI: 10.1039/d0nr02043e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this study, we have investigated the influence of the tip on the three-dimensional scanning force microscopy (3D-SFM) images of calcite-water interfaces by experiments and simulations. We calculated 3D force images by simulations with the solvent tip approximation (STA), Ca, CO3 and OH tip models. For all the 3D images, the z profiles at the surface Ca and CO3 sites alternately show oscillatory peaks corresponding to the hydration layers. However, the peak heights and spacings become larger when the mechanical stability of the tip becomes higher. For analyzing the xy slices of the 3D force images, we developed the extended STA (E-STA) model which allowed us to reveal the strong correlation between the hydration structure just under the tip and the atomic-scale force contrasts. Based on these understandings on the image features showing the strong tip dependence, we developed a method for objectively estimating the similarity between 3D force images. With this method, we compared the simulated images with the three experimentally obtained ones. Among them, two images showed a relatively high similarity with the image obtained by the simulation with the Ca or the CO3 tip model. Based on these agreements, we characterized the hydration structure and mechanical stability of the experimentally used tips. The understanding and methodology presented here should help us to derive accurate information on the tip and the interfacial structure from experimentally obtained 3D-SFM images.
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Affiliation(s)
- Keisuke Miyazawa
- Faculty of Frontier Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. and Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - John Tracey
- Department of Applied Physics, Aalto University, Helsinki FI-00076, Finland.
| | - Bernhard Reischl
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, PO Box 64, FI-00014, Finland and Curtin Institute for Computation, Curtin University, P.O. Box U1987, Perth, Western Australia 6845, Australia
| | - Peter Spijker
- Department of Applied Physics, Aalto University, Helsinki FI-00076, Finland.
| | - Adam S Foster
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan and Department of Applied Physics, Aalto University, Helsinki FI-00076, Finland.
| | - Andrew L Rohl
- Curtin Institute for Computation and School of Electrical Engineering, Computing and Mathematical Sciences, Curtin University, P.O. Box U1987, Perth, Western Australia 6845, Australia
| | - Takeshi Fukuma
- Faculty of Frontier Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. and Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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7
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Legg BA, Baer MD, Chun J, Schenter GK, Huang S, Zhang Y, Min Y, Mundy CJ, De Yoreo JJ. Visualization of Aluminum Ions at the Mica Water Interface Links Hydrolysis State-to-Surface Potential and Particle Adhesion. J Am Chem Soc 2020; 142:6093-6102. [DOI: 10.1021/jacs.9b12530] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Benjamin A. Legg
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Departments of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Marcel D. Baer
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Jaehun Chun
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Gregory K. Schenter
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Shifeng Huang
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Yuanzhong Zhang
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
- Department of Chemical and Environmental Engineering, University of California—Riverside, Riverside, California 92507, United States
| | - Younjin Min
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
- Department of Chemical and Environmental Engineering, University of California—Riverside, Riverside, California 92507, United States
| | - Christopher J. Mundy
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - James J. De Yoreo
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Departments of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
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8
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Teduka Y, Sasahara A, Onishi H. Atomic Force Microscopy Imaging of Crystalline Sucrose in Alcohols. ACS OMEGA 2020; 5:2569-2574. [PMID: 32095681 PMCID: PMC7033667 DOI: 10.1021/acsomega.9b02660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 01/24/2020] [Indexed: 06/10/2023]
Abstract
Imaging nanometer- or molecule-scale topography has been achieved by dynamic atomic force microscopy (AFM) when a solid object of interest is damaged by vacuum exposure or electron irradiation. Imaging in a liquid offers a means to remove contaminations from the surface scanned using the microscope tip when the object is soluble to the surrounding liquid, typically water. In the present study, we attempted to take topographic images of crystalline sucrose. A problem arose due to the high solubility of this compound to water. Cantilever oscillation could not be excited in the saturated, viscous aqueous solution. By using n-hexanol instead of water, the solubility in the solvent and thus viscosity of the solution were reduced sufficiently to excite cantilever oscillation. Single-height steps and sucrose molecules were recognized in the images and thereby recorded on the (001)-oriented facets of sucrose crystals. Furthermore, two-dimensional distribution of liquid-induced force pushing or pulling the tip was mapped on planes perpendicular to the hexanol-sucrose interface. Observed uneven force distributions indicated liquid hexanol structured on the corrugated surface of sucrose. The viscosity tuning demonstrated here, which is not limited to hexanol instead of water, extends the range of liquid-solid interfaces to be probed by dynamic AFM.
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9
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Cao D, Song Y, Peng J, Ma R, Guo J, Chen J, Li X, Jiang Y, Wang E, Xu L. Advances in Atomic Force Microscopy: Weakly Perturbative Imaging of the Interfacial Water. Front Chem 2019; 7:626. [PMID: 31572715 PMCID: PMC6751248 DOI: 10.3389/fchem.2019.00626] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/30/2019] [Indexed: 11/17/2022] Open
Abstract
The structure and dynamics of interfacial water, determined by the water-interface interactions, are important for a wide range of applied fields and natural processes, such as water diffusion (Kim et al., 2013), electrochemistry (Markovic, 2013), heterogeneous catalysis (Over et al., 2000), and lubrication (Zilibotti et al., 2013). The precise understanding of water-interface interactions largely relies on the development of atomic-scale experimental techniques (Guo et al., 2014) and computational methods (Hapala et al., 2014b). Scanning probe microscopy has been extensively applied to probe interfacial water in many interdisciplinary fields (Ichii et al., 2012; Shiotari and Sugimoto, 2017; Peng et al., 2018a). In this perspective, we review the recent progress in the noncontact atomic force microscopy (nc-AFM) imaging and AFM simulation techniques and discuss how the newly developed techniques are applied to study the properties of interfacial water. The nc-AFM with the quadrupole-like CO-terminated tip can achieve ultrahigh-resolution imaging of the interfacial water on different surfaces, trace the reconstruction of H-bonding network and determine the intrinsic structures of the weakly bonded water clusters and even their metastable states. In the end, we present an outlook on the directions of future AFM studies of interfacial water as well as the challenges faced by this field.
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Affiliation(s)
- Duanyun Cao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Yizhi Song
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Jinbo Peng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.,Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Runze Ma
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Jing Guo
- College of Chemistry, Beijing Normal University, Beijing, China
| | - Ji Chen
- School of Physics, Peking University, Beijing, China
| | - Xinzheng Li
- School of Physics, Peking University, Beijing, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China.,CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, China
| | - Enge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.,Ceramics Division, Songshan Lake Materials Lab, Institute of Physics, Chinese Academy of Sciences, Guangdong, China.,School of Physics, Liaoning University, Shenyang, China
| | - Limei Xu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
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10
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Molino PJ, Yang D, Penna M, Miyazawa K, Knowles BR, MacLaughlin S, Fukuma T, Yarovsky I, Higgins MJ. Hydration Layer Structure of Biofouling-Resistant Nanoparticles. ACS NANO 2018; 12:11610-11624. [PMID: 30335960 DOI: 10.1021/acsnano.8b06856] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hydrophilic surface chemistries can strongly bind water to produce surfaces that are highly resistant to protein adsorption and fouling. The interfacial bound water and its distinct properties have intrigued researchers for decades, yet the relationship between the water three-dimensional structure and function in antifouling coatings remains elusive. Here, we use hydrophilic, epoxy organosilane modified silica nanoparticles to demonstrate cheap, robust, and practically applied coatings that we discover have broad-ranging, ultralow fouling properties when challenged by various proteins, bacteria, and fungal spores. To understand their excellent antifouling properties, frequency modulation-atomic force microscopy is used to directly observe the interfacial water structure at subatomic resolution, which we validate using all-atom molecular dynamic simulations that strikingly predict similar structures of water layers on the original and ultralow fouling surfaces. The convergence of experimental and modeling data reveals that suitably spaced, flexible chains with hydrophilic groups interact with water molecules to produce a connective, quasi-stable layer, consisting of dynamic interfacial water, that provides a basis for antifouling performance of ultrathin, hydrophilic surface chemistries.
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Affiliation(s)
- Paul J Molino
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- ARC Centre for Electromaterials Science (ACES), Intelligent Polymer Research Institute/AIIM Faculty, Innovation Campus, Squires Way , University of Wollongong , Wollongong , NSW 2522 , Australia
| | - Dan Yang
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- ARC Centre for Electromaterials Science (ACES), Intelligent Polymer Research Institute/AIIM Faculty, Innovation Campus, Squires Way , University of Wollongong , Wollongong , NSW 2522 , Australia
| | - Matthew Penna
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- School of Engineering , RMIT University , Melbourne , Victoria 3001 , Australia
| | - Keisuke Miyazawa
- Division of Electronic Engineering and Computer Science and ∞Nano Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Brianna R Knowles
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- BlueScope Innovation Laboratories , Old Port Road , Port Kembla , NSW 2505 , Australia
| | - Shane MacLaughlin
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- BlueScope Innovation Laboratories , Old Port Road , Port Kembla , NSW 2505 , Australia
| | - Takeshi Fukuma
- Division of Electronic Engineering and Computer Science and ∞Nano Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Irene Yarovsky
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- School of Engineering , RMIT University , Melbourne , Victoria 3001 , Australia
| | - Michael J Higgins
- ARC Industrial Transformation Research Hub for Australian Steel Manufacturing , Wollongong , NSW 2522 , Australia
- ARC Centre for Electromaterials Science (ACES), Intelligent Polymer Research Institute/AIIM Faculty, Innovation Campus, Squires Way , University of Wollongong , Wollongong , NSW 2522 , Australia
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11
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Atomic-resolution three-dimensional hydration structures on a heterogeneously charged surface. Nat Commun 2017; 8:2111. [PMID: 29235462 PMCID: PMC5727385 DOI: 10.1038/s41467-017-01896-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 10/24/2017] [Indexed: 11/16/2022] Open
Abstract
Local hydration structures at the solid–liquid interface around boundary edges on heterostructures are key to an atomic-level understanding of various physical, chemical and biological processes. Recently, we succeeded in visualising atomic-scale three-dimensional hydration structures by using ultra-low noise frequency-modulation atomic force microscopy. However, the time-consuming three-dimensional-map measurements on uneven heterogeneous surfaces have not been achieved due to experimental difficulties, to the best of our knowledge. Here, we report the local hydration structures formed on a heterogeneously charged phyllosilicate surface using a recently established fast and nondestructive acquisition protocol. We discover intermediate regions formed at step edges of the charged surface. By combining with molecular dynamics simulations, we reveal that the distinct structural hydrations are hard to observe in these regions, unlike the charged surface regions, possibly due to the depletion of ions at the edges. Our methodology and findings could be crucial for the exploration of further functionalities. Local hydration structures at solid-liquid interfaces are important in catalytic, electrochemical, and biological processes. Here, the authors demonstrate atomic-scale 3D hydration structures around the boundary on a heterogeneous mineral surface using atomic force microscopy experiments and molecular dynamics simulations.
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12
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Ricci M, Trewby W, Cafolla C, Voïtchovsky K. Direct observation of the dynamics of single metal ions at the interface with solids in aqueous solutions. Sci Rep 2017; 7:43234. [PMID: 28230209 PMCID: PMC5322364 DOI: 10.1038/srep43234] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/23/2017] [Indexed: 01/14/2023] Open
Abstract
The dynamics of ions adsorbed at the surface of immersed charged solids plays a central role in countless natural and industrial processes such as crystal growth, heterogeneous catalysis, electrochemistry, or biological function. Electrokinetic measurements typically distinguish between a so-called Stern layer of ions and water molecules directly adsorbed on to the solid’s surface, and a diffuse layer of ions further away from the surface. Dynamics within the Stern layer remain poorly understood, largely owing to a lack of in-situ atomic-level insights. Here we follow the dynamics of single Rb+ and H3O+ ions at the surface of mica in water using high-resolution atomic force microscopy with 25 ms resolution. Our results suggest that single hydrated Rb+ions reside τ1 = 104 ± 5 ms at a given location, but this is dependent on the hydration state of the surface which evolves on a slower timescale of τ2 = 610 ± 30 ms depending on H3O+ adsorption. Increasing the liquid’s temperature from 5 °C to 65 °C predictably decreases the apparent glassiness of the interfacial water, but no clear effect on the ions’ dynamics was observed, indicating a diffusion-dominated process. These timescales are remarkably slow for individual monovalent ions and could have important implications for interfacial processes in electrolytes.
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Affiliation(s)
- Maria Ricci
- University of Cambridge, Cavendish Laboratory, Cambridge CB3 0HE, UK
| | - William Trewby
- Department of Physics, Durham University, Durham DH1 3LE, UK
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