1
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Nickel O, Ahrens-Iwers LJV, Meißner RH, Janssen M. Water, Not Salt, Causes Most of the Seebeck Effect of Nonisothermal Aqueous Electrolytes. PHYSICAL REVIEW LETTERS 2024; 132:186201. [PMID: 38759182 DOI: 10.1103/physrevlett.132.186201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 12/05/2023] [Accepted: 04/01/2024] [Indexed: 05/19/2024]
Abstract
A temperature difference between two electrolyte-immersed electrodes often yields a voltage Δψ between them. This electrolyte Seebeck effect is usually explained by cations and anions flowing differently in thermal gradients. However, using molecular simulations, we found almost the same Δψ for cells filled with pure water as with aqueous alkali halides. Water layering and orientation near polarizable electrodes cause a large temperature-dependent potential drop χ there. The difference in χ of hot and cold electrodes captures most of the thermovoltage, Δψ≈χ_{hot}-χ_{cold}.
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Affiliation(s)
- Ole Nickel
- Institute of Polymers and Composites, Hamburg University of Technology, Hamburg, Germany
| | | | - Robert H Meißner
- Institute of Polymers and Composites, Hamburg University of Technology, Hamburg, Germany
- Institute of Surface Science, Helmholtz-Zentrum Hereon, Geesthacht, Germany
| | - Mathijs Janssen
- Norwegian University of Life Sciences, Faculty of Science and Technology, Ås, Norway
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2
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Devlin SW, Bernal F, Riffe EJ, Wilson KR, Saykally RJ. Spiers Memorial Lecture: Water at interfaces. Faraday Discuss 2024; 249:9-37. [PMID: 37795954 DOI: 10.1039/d3fd00147d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
In this article we discuss current issues in the context of the four chosen subtopics for the meeting: dynamics and nano-rheology of interfacial water, electrified/charged aqueous interfaces, ice interfaces, and soft matter/water interfaces. We emphasize current advances in both theory and experiment, as well as important practical manifestations and areas of unresolved controversy.
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Affiliation(s)
- Shane W Devlin
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
| | - Franky Bernal
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
| | - Erika J Riffe
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
| | - Kevin R Wilson
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
| | - Richard J Saykally
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
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3
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Dey S, Folkestad SD, Paul AC, Koch H, Krylov AI. Core-ionization spectrum of liquid water. Phys Chem Chem Phys 2024; 26:1845-1859. [PMID: 38174659 DOI: 10.1039/d3cp02499g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
We present state-of-the-art calculations of the core-ionization spectrum of water. Despite significant progress in procedures developed to mitigate various experimental complications and uncertainties, the experimental determination of ionization energies of solvated species involves several non-trivial steps such as assessing the effect of the surface potential, electrolytes, and finite escape depths of photoelectrons. This provides a motivation to obtain robust theoretical values of the intrinsic bulk ionization energy and the corresponding solvent-induced shift. Here we develop theoretical protocols based on coupled-cluster theory and electrostatic embedding. Our value of the intrinsic solvent-induced shift of the 1sO ionization energy of water is -1.79 eV. The computed absolute position and the width of the 1sO peak in photoelectron spectrum of water are 538.47 eV and 1.44 eV, respectively, agreeing well with the best experimental values.
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Affiliation(s)
- Sourav Dey
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
| | - Sarai Dery Folkestad
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
| | - Alexander C Paul
- Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Henrik Koch
- Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
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4
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Kwan V, Consta S, Malek SMA. Variation of Surface Propensity of Halides with Droplet Size and Temperature: The Planar Interface Limit. J Phys Chem B 2024; 128:193-207. [PMID: 38127582 DOI: 10.1021/acs.jpcb.3c05701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The radial number density profiles of halide and alkali ions in aqueous clusters with equimolar radius ≲1.4 nm, which correspond to ≲255 H2O molecules, have been extensively studied by computations. However, the surface abundance of Cl-, Br-, and I- relative to the bulk interior in these smaller clusters may not be representative of the larger systems. Indeed, here we show that the larger the cluster is, the lower the relative surface abundance of chaotropic halides is. In droplets with an equimolar radius of ≈2.45 nm, which corresponds to ≈2000 H2O molecules, the polarizable halides show a clear number density maximum in the droplet's bulk-like interior. A similar pattern is observed in simulations of the aqueous planar interface with halide salts at room temperature. At elevated temperature the surface propensity of Cl- decreases gradually, while that of I- is partially preserved. The change in the chaotropic halide location at higher temperatures than the room temperature may considerably affect photochemical reactivity in atmospheric aerosols, vapor-liquid nucleation and growth mechanisms, and salt crystallization via solvent evaporation. We argue that the commonly used approach of nullifying parameters in a force field in order to find the factors that determine the ion location does not provide transferable insight into other force fields.
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Affiliation(s)
- Victor Kwan
- Department of Chemistry, The University of Western Ontario, London, ON, Canada N6A 5B7
| | - Styliani Consta
- Department of Chemistry, The University of Western Ontario, London, ON, Canada N6A 5B7
| | - Shahrazad M A Malek
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL, Canada A1B 3X7
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5
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Becker M, Loche P, Rezaei M, Wolde-Kidan A, Uematsu Y, Netz RR, Bonthuis DJ. Multiscale Modeling of Aqueous Electric Double Layers. Chem Rev 2024; 124:1-26. [PMID: 38118062 PMCID: PMC10785765 DOI: 10.1021/acs.chemrev.3c00307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 11/17/2023] [Accepted: 11/30/2023] [Indexed: 12/22/2023]
Abstract
From the stability of colloidal suspensions to the charging of electrodes, electric double layers play a pivotal role in aqueous systems. The interactions between interfaces, water molecules, ions and other solutes making up the electrical double layer span length scales from Ångströms to micrometers and are notoriously complex. Therefore, explaining experimental observations in terms of the double layer's molecular structure has been a long-standing challenge in physical chemistry, yet recent advances in simulations techniques and computational power have led to tremendous progress. In particular, the past decades have seen the development of a multiscale theoretical framework based on the combination of quantum density functional theory, force-field based simulations and continuum theory. In this Review, we discuss these theoretical developments and make quantitative comparisons to experimental results from, among other techniques, sum-frequency generation, atomic-force microscopy, and electrokinetics. Starting from the vapor/water interface, we treat a range of qualitatively different types of surfaces, varying from soft to solid, from hydrophilic to hydrophobic, and from charged to uncharged.
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Affiliation(s)
| | - Philip Loche
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Laboratory
of Computational Science and Modeling, IMX, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Majid Rezaei
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Institute
of Theoretical Chemistry, Ulm University, 89081 Ulm, Germany
| | | | - Yuki Uematsu
- Department
of Physics and Information Technology, Kyushu
Institute of Technology, 820-8502 Iizuka, Japan
- PRESTO,
Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Roland R. Netz
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Douwe Jan Bonthuis
- Institute
of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria
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6
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Rashid MAM, Rahman M, Acter T, Uddin N. Identifying the acidic or basic behavior of surface water: a QM/MM-MD study. Phys Chem Chem Phys 2023; 25:31194-31205. [PMID: 37955174 DOI: 10.1039/d3cp02080k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
Controversies on the water surface were theoretically addressed with the help of large scale quantum mechanical molecular dynamics (QMMD) simulations on water surface model systems with and without excess hydroniums and hydroxides. It was revealed that the thermodynamic surface structures of these ions strongly depend on their location and dipole orientation. Fast hydronium diffusion by proton transfer establishes a wider kinetic depth distribution (∼6 Å) than that predicted by its thermodynamic affinity for the water surface, while slow hydroxide is shallowly trapped below the outermost molecular layer (3-4 Å). In addition, the anisotropic orientation of surface water dipole can generate a substantial magnitude of surface potential, which extends to a depth of a few molecular layers. With these distinctively different surface properties of two ions and water molecules, the seemingly contradictory observations of acidic and negatively charged water surfaces may be successfully explained. That is, the negative surface charge of neutral water mostly stems from intrinsic water properties such as water dipole orientation and electron density spillage at the surface, rather than surface OH- ions. The enhanced acidity of the water surface can be attributed in large part to the kinetic depth profile of ion density in addition to static thermodynamic origin. Furthermore, the different depth profiles of the two ions may differently affect the surface-sensitive spectroscopic observations.
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Affiliation(s)
- Md Al Mamunur Rashid
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Mofizur Rahman
- Research and Development Center, Berger Paints Bangladesh Limited, Berger House, Dhaka-1230, Bangladesh
| | - Thamina Acter
- Department of Mathematical and Physical Sciences, East West University, Aftabnagar, Dhaka-1212, Bangladesh
| | - Nizam Uddin
- Department of Nutrition and Food Engineering, Daffodil International University, Birulia, Dhaka-1216, Bangladesh.
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7
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Pugini M, Credidio B, Walter I, Malerz S, Trinter F, Stemer D, Hergenhahn U, Meijer G, Wilkinson I, Winter B, Thürmer S. How to measure work functions from aqueous solutions. Chem Sci 2023; 14:9574-9588. [PMID: 37712029 PMCID: PMC10498509 DOI: 10.1039/d3sc01740k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/28/2023] [Indexed: 09/16/2023] Open
Abstract
The recent application of concepts from condensed-matter physics to photoelectron spectroscopy (PES) of volatile, liquid-phase systems has enabled the measurement of electronic energetics of liquids on an absolute scale. Particularly, vertical ionization energies, VIEs, of liquid water and aqueous solutions, both in the bulk and at associated interfaces, can now be accurately, precisely, and routinely determined. These IEs are referenced to the local vacuum level, which is the appropriate quantity for condensed matter with associated surfaces, including liquids. In this work, we connect this newly accessible energy level to another important surface property, namely, the solution work function, eΦliq. We lay out the prerequisites for and unique challenges of determining eΦ of aqueous solutions and liquids in general. We demonstrate - for a model aqueous solution with a tetra-n-butylammonium iodide (TBAI) surfactant solute - that concentration-dependent work functions, associated with the surface dipoles generated by the segregated interfacial layer of TBA+ and I- ions, can be accurately measured under controlled conditions. We detail the nature of surface potentials, uniquely tied to the nature of the flowing-liquid sample, which must be eliminated or quantified to enable such measurements. This allows us to refer aqueous-phase spectra to the Fermi level and to quantitatively assign surfactant-concentration-dependent spectral shifts to competing work function and electronic-structure effects, where the latter are typically associated with solute-solvent interactions in the bulk of the solution which determine, e.g., chemical reactivity. The present work describes the extension of liquid-jet PES to quantitatively access concentration-dependent surface descriptors that have so far been restricted to solid-phase measurements. Correspondingly, these studies mark the beginning of a new era in the characterization of the interfacial electronic structure of aqueous solutions and liquids more generally.
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Affiliation(s)
- Michele Pugini
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Bruno Credidio
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Irina Walter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Sebastian Malerz
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Florian Trinter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
- Institut für Kernphysik, Goethe-Universität Max-von-Laue-Straße 1 60438 Frankfurt am Main Germany
| | - Dominik Stemer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Uwe Hergenhahn
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Iain Wilkinson
- Institute for Electronic Structure Dynamics, Helmholtz-Zentrum Berlin für Materialien und Energie Hahn-Meitner-Platz 1 14109 Berlin Germany
| | - Bernd Winter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Stephan Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University Kitashirakawa-Oiwakecho, Sakyo-Ku 606-8502 Kyoto Japan
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8
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Hantal G, Klíma M, McFegan L, Kolafa J, Jedlovszky P. Does the Sign of Charge Affect the Surface Affinity of Simple Ions? J Phys Chem B 2023. [PMID: 37399285 DOI: 10.1021/acs.jpcb.3c02641] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
The role the charge sign of simple ions plays in determining their surface affinity in aqueous solutions is investigated by computer simulation methods. For this purpose, the free surface of aqueous solutions of fictitious salts is simulated at finite concentration both with nonpolarizable point-charge and polarizable Gaussian-charge potential models. The salts consist of monovalent cations and anions that are, apart from the sign of their charge, identical to each other. In particular, we consider the small Na+ and the large I- ions together with their charge-inverted counterparts. In an attempt to avoid the interference even between the behavior of cations and anions, we also simulate systems containing only one of the above ions, and determine the free energy profile of these ions across the liquid-vapor interface of water at infinite dilution by potential of mean force (PMF) calculations. The obtained results reveal that, in the case of small ions, the anion is hydrated considerably stronger than the cation due to the close approach of water H atoms, bearing a positive fractional charge. As a consequence, the surface affinity of a small anion is even smaller than that of its cationic counterpart. However, considering that small ions are effectively repelled from the water surface, the importance of this difference is negligible. Further, a change in the hydration energy trends of the two oppositely charged ions is observed with their increasing size. This change is largely attributed to the fact that, with increasing ion size, the factor of 2 in the magnitude of the fractional charge of the closely approaching water atoms (i.e., O around cations and H around anions) outweighs the closer approach of the H than the O atom in the hydration energy. Thus, for large ions, being already surface active themselves, the surface affinity of the anion is larger than that of its positively charged counterpart. Further, such a difference is seen even in the case when the sign of the surface potential favors the adsorption of cations.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Martin Klíma
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Louisa McFegan
- Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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9
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Becker MR, Loche P, Netz RR. Electrokinetic, electrochemical, and electrostatic surface potentials of the pristine water liquid-vapor interface. J Chem Phys 2022; 157:240902. [PMID: 36586978 DOI: 10.1063/5.0127869] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Although conceptually simple, the air-water interface displays rich behavior and is subject to intense experimental and theoretical investigations. Different definitions of the electrostatic surface potential as well as different calculation methods, each relevant for distinct experimental scenarios, lead to widely varying potential magnitudes and sometimes even different signs. Based on quantum-chemical density-functional-theory molecular dynamics (DFT-MD) simulations, different surface potentials are evaluated and compared to force-field (FF) MD simulations. As well explained in the literature, the laterally averaged electrostatic surface potential, accessible to electron holography, is dominated by the trace of the water molecular quadrupole moment, and using DFT-MD amounts to +4.35 V inside the water phase, very different from results obtained with FF water models which yield negative values of the order of -0.4 to -0.6 V. Thus, when predicting potentials within water molecules, as relevant for photoelectron spectroscopy and non-linear interface-specific spectroscopy, DFT simulations should be used. The electrochemical surface potential, relevant for ion transfer reactions and ion surface adsorption, is much smaller, less than 200 mV in magnitude, and depends specifically on the ion radius. Charge transfer between interfacial water molecules leads to a sizable surface potential as well. However, when probing electrokinetics by explicitly applying a lateral electric field in DFT-MD simulations, the electrokinetic ζ-potential turns out to be negligible, in agreement with predictions using continuous hydrodynamic models. Thus, interfacial polarization charges from intermolecular charge transfer do not lead to significant electrokinetic mobility at the pristine vapor-liquid water interface, even assuming these transfer charges are mobile in an external electric field.
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Affiliation(s)
| | - Philip Loche
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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10
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Hao H, Ruiz Pestana L, Qian J, Liu M, Xu Q, Head‐Gordon T. Chemical transformations and transport phenomena at interfaces. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hongxia Hao
- Kenneth S. Pitzer Theory Center and Department of Chemistry University of California Berkeley California USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory Berkeley California USA
| | - Luis Ruiz Pestana
- Department of Civil and Architectural Engineering University of Miami Coral Gables Florida USA
| | - Jin Qian
- Chemical Sciences Division Lawrence Berkeley National Laboratory Berkeley California USA
| | - Meili Liu
- Department of Civil and Architectural Engineering University of Miami Coral Gables Florida USA
| | - Qiang Xu
- Chemical Sciences Division Lawrence Berkeley National Laboratory Berkeley California USA
| | - Teresa Head‐Gordon
- Kenneth S. Pitzer Theory Center and Department of Chemistry University of California Berkeley California USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory Berkeley California USA
- Department of Bioengineering and Chemical and Biomolecular Engineering University of California Berkeley California USA
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11
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Rehl B, Ma E, Parshotam S, DeWalt-Kerian EL, Liu T, Geiger FM, Gibbs JM. Water Structure in the Electrical Double Layer and the Contributions to the Total Interfacial Potential at Different Surface Charge Densities. J Am Chem Soc 2022; 144:16338-16349. [PMID: 36042195 DOI: 10.1021/jacs.2c01830] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The electric double layer governs the processes of all charged surfaces in aqueous solutions; however, elucidating the structure of the water molecules is challenging for even the most advanced spectroscopic techniques. Here, we present the individual Stern layer and diffuse layer OH stretching spectra at the silica/water interface in the presence of NaCl over a wide pH range using a combination of vibrational sum frequency generation spectroscopy, heterodyned second harmonic generation, and streaming potential measurements. We find that the Stern layer water molecules and diffuse layer water molecules respond differently to pH changes: unlike the diffuse layer, whose water molecules remain net-oriented in one direction, water molecules in the Stern layer flip their net orientation as the solution pH is reduced from basic to acidic. We obtain an experimental estimate of the non-Gouy-Chapman (Stern) potential contribution to the total potential drop across the insulator/electrolyte interface and discuss it in the context of dipolar, quadrupolar, and higher order potential contributions that vary with the observed changes in the net orientation of water in the Stern layer. Our findings show that a purely Gouy-Chapman (Stern) view is insufficient to accurately describe the electrical double layer of aqueous interfaces.
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Affiliation(s)
- Benjamin Rehl
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Emily Ma
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Shyam Parshotam
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Emma L DeWalt-Kerian
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Tianli Liu
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Franz M Geiger
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Julianne M Gibbs
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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12
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Loche P, Scalfi L, Ali Amu M, Schullian O, Bonthuis D, Rotenberg B, Netz RR. Effects of surface rigidity and metallicity on dielectric properties and ion interactions at aqueous hydrophobic interfaces. J Chem Phys 2022; 157:094707. [DOI: 10.1063/5.0101509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using classical molecular dynamics simulations we investigate the dielectric properties at interfaces of water with graphene, graphite, hexane and water vapor. For graphite we compare metallic and non-metallic versions. At the vapor-liquid water and hexane-water interfaces the laterally averaged dielectric profiles are significantly broadened due to interfacial roughness and only slightly anisotropic. In contrast, at the rigid graphene surface the dielectric profiles are strongly anisotropic and the perpendicular dielectric profile exhibits pronounced oscillations and sign changes. The interfacial dielectric excess, characterized by the shift of the dielectric-dividing-surface with respect to the Gibbs-dividing-surface, is positive for all surfaces, showing that water has an enhanced dielectric response at hydrophobic surfaces. The dielectric-dividing-surface positions vary significantly among the different surfaces, which points to pronounced surface-specific dielectric behavior. The interfacial repulsion of a chloride ion is shown to be dominated by electrostatic interactions for the soft fluid-fluid interfaces and by non-electrostatic Lennard-Jones interactions for the rigid graphene-water interface. A linear tensorial dielectric model for the ion-interface interaction with sharp dielectric interfaces located on the dielectric-dividing-surface positions works well for graphene but fails for vapor and hexane, because these interfaces are smeared out. The repulsion of chloride from the metallic and non-metallic graphite versions differs very little, which reflects the almost identical interfacial water structure and can be understood based on linear continuum dielectric theory. Interface flexibility shows up mostly in the non-linear Coulomb part of the ion-interface interaction, which changes significantly close to the interfaces and signals the breakdown of linear dielectric continuum theory.
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Affiliation(s)
| | - Laura Scalfi
- Freie Universitat Berlin Fachbereich Physik, Germany
| | | | - Otto Schullian
- Max Planck Institute of Colloids and Interfaces, Germany
| | - Douwe Bonthuis
- Institute of Theoretical and Computational Physics, Graz University of Technology Institute of Theoretical and Computational Physics, Austria
| | | | - Roland R. Netz
- Physics, Freie Universitat Berlin Fachbereich Physik, Germany
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13
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Walker-Gibbons R, Kubincová A, Hünenberger PH, Krishnan M. The Role of Surface Chemistry in the Orientational Behavior of Water at an Interface. J Phys Chem B 2022; 126:4697-4710. [PMID: 35726865 PMCID: PMC9251758 DOI: 10.1021/acs.jpcb.2c01752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Molecular dynamics
studies have demonstrated that molecular water
at an interface, with either a gas or a solid, displays anisotropic
orientational behavior in contrast to its bulk counterpart. This effect
has been recently implicated in the like-charge attraction problem
for colloidal particles in solution. Here, negatively charged particles
in solution display a long-ranged attraction where continuum electrostatic
theory predicts monotonically repulsive interactions, particularly
in solutions with monovalent salt ions at low ionic strength. Anisotropic
orientational behavior of solvent molecules at an interface gives
rise to an excess interfacial electrical potential which we suggest
generates an additional solvation contribution to the total free energy
that is traditionally overlooked in continuum descriptions of interparticle
interactions in solution. In the present investigation we perform
molecular dynamics simulation based calculations of the interfacial
potential using realistic surface models representing various chemistries
as well as different solvents. Similar to previous work that focused
on simple model surfaces constructed by using oxygen atoms, we find
that solvents at more realistic model surfaces exhibit substantial
anisotropic orientational behavior. We explore the dependence of the
interfacial solvation potential on surface properties such as surface
group chemistry and group density at silica and carboxylated polystyrene
interfaces. For water, we note surprisingly good agreement between
results obtained for a simple O-atom wall and more complex surface
models, suggesting a general qualitative consistency of the interfacial
solvation effect for surfaces in contact with water. In contrast,
for an aprotic solvent such as DMSO, surface chemistry appears to
exert a stronger influence on the sign and magnitude of the interfacial
solvation potential. The study carries broad implications for molecular-scale
interactions and may find relevance in explaining a range of phenomena
in soft-matter physics and cell biology.
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Affiliation(s)
- Rowan Walker-Gibbons
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alžbeta Kubincová
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Philippe H Hünenberger
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Madhavi Krishnan
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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14
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Qiu L, Morato NM, Huang KH, Cooks RG. Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets. Front Chem 2022; 10:903774. [PMID: 35559217 PMCID: PMC9086510 DOI: 10.3389/fchem.2022.903774] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/11/2022] [Indexed: 12/20/2022] Open
Abstract
Spontaneous oxidation of compounds containing diverse X=Y moieties (e.g., sulfonamides, ketones, esters, sulfones) occurs readily in organic-solvent microdroplets. This surprising phenomenon is proposed to be driven by the generation of an intermediate species [M+H2O]+·: a covalent adduct of water radical cation (H2O+·) with the reactant molecule (M). The adduct is observed in the positive ion mass spectrum while its formation in the interfacial region of the microdroplet (i.e., at the air-droplet interface) is indicated by the strong dependence of the oxidation product formation on the spray distance (which reflects the droplet size and consequently the surface-to-volume ratio) and the solvent composition. Importantly, based on the screening of a ca. 21,000-compound library and the detailed consideration of six functional groups, the formation of a molecular adduct with the water radical cation is a significant route to ionization in positive ion mode electrospray, where it is favored in those compounds with X=Y moieties which lack basic groups. A set of model monofunctional systems was studied and in one case, benzyl benzoate, evidence was found for oxidation driven by hydroxyl radical adduct formation followed by protonation in addition to the dominant water radical cation addition process. Significant implications of molecular ionization by water radical cations for oxidation processes in atmospheric aerosols, analytical mass spectrometry and small-scale synthesis are noted.
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15
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Behjatian A, Walker-Gibbons R, Schekochihin AA, Krishnan M. Nonmonotonic Pair Potentials in the Interaction of Like-Charged Objects in Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:786-800. [PMID: 34981941 DOI: 10.1021/acs.langmuir.1c02801] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We consider the long-standing like-charge attraction problem, wherein under certain conditions, similarly charged spheres suspended in aqueous electrolyte have been observed to display a minimum in their interaction potential, contrary to the intuitively expected monotonically varying repulsion. Recently, we described an interfacial mechanism invoking the molecular nature of the solvent that explains this anomalous experimental observation. In our model for the interaction of negatively charged particles in water, the minimum in the pair potential results from the superposition of competing contributions to the total free energy. One of these contributions is the canonical repulsive electrostatic term, whereas the other is a solvation-induced attractive contribution. We find that whereas both contributions grow approximately exponentially with decreasing interparticle separation, the occurrence of a stable, long-ranged minimum in the pair potential arises from differences in the precise interparticle separation dependence of the two terms. Specifically, the interfacial solvation term exhibits a more gradual decay with distance than the electrostatic repulsion, permitting the attractive contribution to dominate the interaction at large distances. Importantly, these disparities become evident in quantities calculated from exact numerical solutions to the governing nonlinear Poisson-Boltzmann (PB) equation for the spatial electrical potential distribution in the system. In marked contrast, we find that the linearized PB equation, applicable in the regime of low surface electrical potentials, does not support nonmonotonic trends in the total interaction free energy within the present model. Our results point to the importance of exact descriptions of electrostatic interactions in real systems that most often do not subscribe to particular mathematical limits where analytical approximations may provide a sufficiently accurate description of the problem.
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Affiliation(s)
- Ali Behjatian
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Rowan Walker-Gibbons
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alexander A Schekochihin
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
- Merton College, Merton Street, Oxford OX1 4JD, United Kingdom
| | - Madhavi Krishnan
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
- Merton College, Merton Street, Oxford OX1 4JD, United Kingdom
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16
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Hao H, Leven I, Head-Gordon T. Can electric fields drive chemistry for an aqueous microdroplet? Nat Commun 2022; 13:280. [PMID: 35022410 PMCID: PMC8755715 DOI: 10.1038/s41467-021-27941-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 12/14/2021] [Indexed: 11/20/2022] Open
Abstract
Reaction rates of common organic reactions have been reported to increase by one to six orders of magnitude in aqueous microdroplets compared to bulk solution, but the reasons for the rate acceleration are poorly understood. Using a coarse-grained electron model that describes structural organization and electron densities for water droplets without the expense of ab initio methods, we investigate the electric field distributions at the air-water interface to understand the origin of surface reactivity. We find that electric field alignments along free O-H bonds at the surface are ~16 MV/cm larger on average than that found for O-H bonds in the interior of the water droplet. Furthermore, electric field distributions can be an order of magnitude larger than the average due to non-linear coupling of intramolecular solvent polarization with intermolecular solvent modes which may contribute to even greater surface reactivity for weakening or breaking chemical bonds at the droplet surface.
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Affiliation(s)
- Hongxia Hao
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720, USA
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, CA, 94720, USA
- Departments of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Itai Leven
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720, USA
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, CA, 94720, USA
- Departments of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Teresa Head-Gordon
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720, USA.
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, CA, 94720, USA.
- Departments of Chemistry, University of California, Berkeley, CA, 94720, USA.
- Departments of Bioengineering, University of California, Berkeley, CA, 94720, USA.
- Departments of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA.
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17
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Shandilya A, Schwarz K, Sundararaman R. Interfacial water asymmetry at ideal electrochemical interfaces. J Chem Phys 2022; 156:014705. [PMID: 34998343 DOI: 10.1063/5.0076038] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Controlling electrochemical reactivity requires a detailed understanding of the charging behavior and thermodynamics of the electrochemical interface. Experiments can independently probe the overall charge response of the electrochemical double layer by capacitance measurements and the thermodynamics of the inner layer with potential of maximum entropy measurements. Relating these properties by computational modeling of the electrochemical interface has so far been challenging due to the low accuracy of classical molecular dynamics (MD) for capacitance and the limited time and length scales of ab initio MD. Here, we combine large ensembles of long-time-scale classical MD simulations with charge response from electronic density functional theory to predict the potential-dependent capacitance of a family of ideal aqueous electrochemical interfaces with different peak capacitances. We show that while the potential of maximum capacitance varies, this entire family exhibits an electrode charge of maximum capacitance (CMC) between -2.9 and -2.2 μC/cm2, regardless of the details in the electronic response. Simulated heating of the same interfaces reveals that the entropy peaks at a charge of maximum entropy (CME) of -5.1 ± 0.6 μC/cm2, in agreement with experimental findings for metallic electrodes. The CME and CMC both indicate asymmetric response of interfacial water that is stronger for negatively charged electrodes, while the difference between CME and CMC illustrates the richness in behavior of even the ideal electrochemical interface.
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Affiliation(s)
- Abhishek Shandilya
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
| | - Kathleen Schwarz
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Ravishankar Sundararaman
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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18
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Cox SJ, Geissler PL. Dielectric response of thin water films: a thermodynamic perspective. Chem Sci 2022; 13:9102-9111. [PMID: 36091210 PMCID: PMC9365083 DOI: 10.1039/d2sc01243j] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/17/2022] [Indexed: 12/24/2022] Open
Abstract
The surface of a polar liquid presents a special environment for the solvation and organization of charged solutes, which differ from bulk behaviors in important ways. These differences have motivated many attempts to understand electrostatic response at aqueous interfaces in terms of a spatially varying dielectric permittivity, typically concluding that the dielectric constant of interfacial water is significantly lower than in the bulk liquid. Such analyses, however, are complicated by the potentially nonlocal nature of dielectric response over the short length scales of interfacial heterogeneity. Here we circumvent this problem for thin water films by adopting a thermodynamic approach. Using molecular simulations, we calculate the solvent's contribution to the reversible work of charging a parallel plate capacitor. We find good agreement with a simple dielectric continuum model that assumes bulk dielectric permittivity all the way up to the liquid's boundary, even for very thin (∼1 nm) films. This comparison requires careful attention to the placement of dielectric boundaries between liquid and vapor, which also resolves apparent discrepancies with dielectric imaging experiments. Free energy calculations from molecular simulations reveal that water's interfacial dielectric response is well-described by bulk properties.![]()
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Affiliation(s)
- Stephen J. Cox
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Phillip L. Geissler
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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19
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Chapman A, Bresme F. Polarisation of water under thermal fields: the effect of the molecular dipole and quadrupole moments. Phys Chem Chem Phys 2022; 24:14924-14936. [DOI: 10.1039/d2cp00756h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The investigation of the behaviour of water under thermal fields is important to understand thermoelectricity of solutions, aqueous suspensions, bioelectric effects or the properties of wet materials under spatially inhomogeneous...
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20
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Kathmann SM. Electric fields and potentials in condensed phases. Phys Chem Chem Phys 2021; 23:23836-23849. [PMID: 34647950 DOI: 10.1039/d1cp03571a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electric fields and potentials inside and at the interface of matter are relevant to many branches of physics, chemistry, and biology. Accurate quantification of these fields and/or potentials is essential to control and exploit chemical and physical transformations. Before we understand the response of matter to external fields, it is first important to understand the intrinsic interior and interfacial fields and potentials, both classically and quantum mechanically, as well as how they are probed experimentally. Here we compare and contrast, beginning with the hydrogen atom in vacuum and ending with concentrated aqueous NaCl electrolyte, both classical and quantum mechanical electric potentials and fields. We make contact with experimental vibrational Stark, electrochemical, X-ray, and electron spectroscopic probes of these potentials and fields, outline relevant conceptual difficulties, and underscore the advantage of electron holography as a basis to better understand electrostatics in matter.
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Affiliation(s)
- Shawn M Kathmann
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA.
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21
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Thakur AC, Remsing RC. Distributed charge models of liquid methane and ethane for dielectric effects and solvation. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1933228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Atul C. Thakur
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
| | - Richard C. Remsing
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
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22
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Chubak I, Scalfi L, Carof A, Rotenberg B. NMR Relaxation Rates of Quadrupolar Aqueous Ions from Classical Molecular Dynamics Using Force-Field Specific Sternheimer Factors. J Chem Theory Comput 2021; 17:6006-6017. [PMID: 34570493 DOI: 10.1021/acs.jctc.1c00690] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nuclear magnetic resonance (NMR) relaxation of quadrupolar nuclei is governed by the electric field gradient (EFG) fluctuations at their position. In classical molecular dynamics (MD), the electron cloud contribution to the EFG can be included via the Sternheimer approximation, in which the full EFG at the nucleus that can be computed using quantum density functional theory (DFT) is considered to be proportional to that arising from the external, classical charge distribution. In this work, we systematically assess the quality of the Sternheimer approximation as well as the impact of the classical force field (FF) on the NMR relaxation rates of aqueous quadrupolar ions at infinite dilution. In particular, we compare the rates obtained using an ab initio parametrized polarizable FF, a recently developed empirical FF with scaled ionic charges and a simple empirical nonpolarizable FF with formal ionic charges. Surprisingly, all three FFs considered yield good values for the rates of smaller and less polarizable solutes (Li+, Na+, K+, Cl-), provided that a model-specific Sternheimer parametrization is employed. Yet, the polarizable and scaled charge FFs yield better estimates for divalent and more polarizable species (Mg2+, Ca2+, Cs+). We find that a linear relationship between the quantum and classical EFGs holds well in all of the cases considered; however, such an approximation often leads to quite large errors in the resulting EFG variance, which is directly proportional to the computed rate. We attempted to reduce the errors by including first order nonlinear corrections to the EFG, yet no clear improvement for the resulting variance has been found. The latter result indicates that more refined methods for determining the EFG at the ion position, in particular those that take into account the instantaneous atomic environment around an ion, might be necessary to systematically improve the NMR relaxation rate estimates in classical MD.
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Affiliation(s)
- Iurii Chubak
- Sorbonne Université CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
| | - Laura Scalfi
- Sorbonne Université CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
| | - Antoine Carof
- Universite de Lorraine, CNRS, LPCT, F-54000, Nancy, France
| | - Benjamin Rotenberg
- Sorbonne Université CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
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23
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Yamamoto YI, Ishiyama T, Morita A, Suzuki T. Exploration of Gas-Liquid Interfaces for Liquid Water and Methanol Using Extreme Ultraviolet Laser Photoemission Spectroscopy. J Phys Chem B 2021; 125:10514-10526. [PMID: 34494839 DOI: 10.1021/acs.jpcb.1c04765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We present a study using extreme UV (EUV) photoemission spectroscopy of the valence electronic structures of aqueous and methanol solutions using a 10 kHz EUV light source based on high-order harmonic generation and a magnetic bottle time-of-flight electron spectrometer. Two aspects of the observed spectra are highlighted in this study. One is variation of the vertical ionization energy (VIE) for liquids as a function of the solute concentration, which is closely related to surface dipoles at the gas-liquid interface. The experimental results show that the VIE of liquid water increases slightly with increasing concentrations of NaCl and NaI and decreases with NaOH. The VIE of liquid methanol was also found to change slightly with NaI. On the other hand, tetrabutylammonium iodide (TBAI) and butylamine (BA) clearly reduce the VIE for liquid water, which is attributed to the formation of an electric double layer (EDL) by segregated solutes at the gas-liquid interface. As evidence for this, when the pH of an aqueous BA solution is reduced to protonate BA, the VIE shift gradually decreases because the protonated BA moves into the bulk to suppress the influence of the EDL. We computed the surface potentials for these solutions using molecular dynamics simulations, and the results supported our interpretation of the experimental results. Another observation is the variation of the relative energy and shape of individual photoelectron bands for solvents, which is related to alteration of the structure and constituents of the first solvation shell of ionized solvent molecules. All of the solutes cause changes in the photoelectron spectra at high concentration, one of the most prominent of which is the degree of splitting of the 3a1 band for liquid water and the 7a' band for liquid methanol, which are sensitive to hydrogen bonding in the liquids. The 3a1 splitting decreases with the increasing concentration of NaI, NaCl, and NaOH, indicating that Na+ penetrates into the hydrogen-bonding network to coordinate to a nonbonding electron of a water molecule. On the other hand, TBAI and BA cause smaller changes in the 3a1 splitting. Full interpretation of these spectroscopic features awaits extensive quantum chemical calculations and is beyond the scope of this study. However, these results illustrate the strong potential of EUV laser photoemission spectroscopy of liquids for exploration of interfacial and solution chemistry.
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Affiliation(s)
- Yo-Ichi Yamamoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Tatsuya Ishiyama
- Department of Applied Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
| | - Akihiro Morita
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.,Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto 615-8530, Japan
| | - Toshinori Suzuki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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24
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Abbas UL, Qiao Q, Nguyen MT, Shi J, Shao Q. Structure and hydrogen bonds of hydrophobic deep eutectic
solvent‐aqueous liquid–liquid
interfaces. AIChE J 2021. [DOI: 10.1002/aic.17427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Usman L. Abbas
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Qi Qiao
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Manh Tien Nguyen
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Jian Shi
- Department of Biosystems and Agricultural Engineering University of Kentucky Lexington Kentucky USA
| | - Qing Shao
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
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25
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Thürmer S, Malerz S, Trinter F, Hergenhahn U, Lee C, Neumark DM, Meijer G, Winter B, Wilkinson I. Accurate vertical ionization energy and work function determinations of liquid water and aqueous solutions. Chem Sci 2021; 12:10558-10582. [PMID: 34447550 PMCID: PMC8356740 DOI: 10.1039/d1sc01908b] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 07/02/2021] [Indexed: 01/29/2023] Open
Abstract
The absolute-scale electronic energetics of liquid water and aqueous solutions, both in the bulk and at associated interfaces, are the central determiners of water-based chemistry. However, such information is generally experimentally inaccessible. Here we demonstrate that a refined implementation of the liquid microjet photoelectron spectroscopy (PES) technique can be adopted to address this. Implementing concepts from condensed matter physics, we establish novel all-liquid-phase vacuum and equilibrated solution–metal-electrode Fermi level referencing procedures. This enables the precise and accurate determination of previously elusive water solvent and solute vertical ionization energies, VIEs. Notably, this includes quantification of solute-induced perturbations of water's electronic energetics and VIE definition on an absolute and universal chemical potential scale. Defining and applying these procedures over a broad range of ionization energies, we accurately and respectively determine the VIE and oxidative stability of liquid water as 11.33 ± 0.03 eV and 6.60 ± 0.08 eV with respect to its liquid-vacuum-interface potential and Fermi level. Combining our referencing schemes, we accurately determine the work function of liquid water as 4.73 ± 0.09 eV. Further, applying our novel approach to a pair of exemplary aqueous solutions, we extract absolute VIEs of aqueous iodide anions, reaffirm the robustness of liquid water's electronic structure to high bulk salt concentrations (2 M sodium iodide), and quantify reference-level dependent reductions of water's VIE and a 0.48 ± 0.13 eV contraction of the solution's work function upon partial hydration of a known surfactant (25 mM tetrabutylammonium iodide). Our combined experimental accomplishments mark a major advance in our ability to quantify electronic–structure interactions and chemical reactivity in liquid water, which now explicitly extends to the measurement of absolute-scale bulk and interfacial solution energetics, including those of relevance to aqueous electrochemical processes. A generalised liquid-phase photoelectron spectroscopy approach is reported, allowing accurate, absolute energy scale ionisation energies of liquid water and aqueous solutions, as well as liquid water's work function to be reported.![]()
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Affiliation(s)
- Stephan Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University Kitashirakawa-Oiwakecho, Sakyo-Ku Kyoto 606-8502 Japan
| | - Sebastian Malerz
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Florian Trinter
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany .,Institut für Kernphysik, Goethe-Universität Max-von-Laue-Straße 1 60438 Frankfurt am Main Germany
| | - Uwe Hergenhahn
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Chin Lee
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany .,Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA.,Department of Chemistry, University of California Berkeley CA 94720 USA
| | - Daniel M Neumark
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA.,Department of Chemistry, University of California Berkeley CA 94720 USA
| | - Gerard Meijer
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Bernd Winter
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 14195 Berlin Germany
| | - Iain Wilkinson
- Department of Locally-Sensitive & Time-Resolved Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie Hahn-Meitner-Platz 1 14109 Berlin Germany
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26
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Pérez Ramírez L, Boucly A, Saudrais F, Bournel F, Gallet JJ, Maisonhaute E, Milosavljević AR, Nicolas C, Rochet F. The Fermi level as an energy reference in liquid jet X-ray photoelectron spectroscopy studies of aqueous solutions. Phys Chem Chem Phys 2021; 23:16224-16233. [PMID: 34304262 DOI: 10.1039/d1cp01511g] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
To advance the understanding of key electrochemical and photocatalytic processes that depend on the electronic structure of aqueous solutions, X-ray photoemission spectroscopy has become an invaluable tool, especially when practiced with liquid microjet setups. Determining vertical ionization energies referenced to the vacuum level, and binding energies referenced to the Fermi level, including the much-coveted reorganization energy of the oxidized species of a redox couple, requires that energy levels be properly defined. The present paper addresses specifically how the vacuum level "just outside the surface" can be known through the energy position of the rising edge of the secondary electrons, and how the Fermi level reference is uniquely determined via the introduction of a redox couple. Taking the case of the ferricyanide/ferrocyanide and ferric/ferrous couples, this study also tackles issues related to the electrokinetic effects inherent to the production of a liquid jet in a vacuum, which has become the standard water sample environment for photoemission experiments.
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Affiliation(s)
- Lucía Pérez Ramírez
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique Matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France.
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27
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Futera Z, English NJ. Water Breakup at Fe 2O 3-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium Ab Initio Molecular Dynamics. J Phys Chem Lett 2021; 12:6818-6826. [PMID: 34270253 PMCID: PMC8397349 DOI: 10.1021/acs.jpclett.1c01479] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/07/2021] [Indexed: 05/25/2023]
Abstract
The dynamical properties of physically and chemically adsorbed water molecules at pristine hematite-(001) surfaces have been studied by means of nonequilibrium ab initio molecular dynamics (NE-AIMD) in the NVT ensemble at room temperature, in the presence of externally applied, uniform static electric fields of increasing intensity. The dissociation of water molecules to form chemically adsorbed species was scrutinized, in addition to charge redistribution and Grotthus proton hopping between water molecules. Dynamical properties of the adsorbed water molecules and OH- and H3O+ ions were gauged, such as the hydrogen bonds between protons in water molecules and the bridging oxygen atoms at the hematite surface, as well as the interactions between oxygen atoms in adsorbed water molecules and iron atoms at the hematite surface. The development of Helmholtz charge layers via water breakup at Fe2O3-hematite/water interfaces is also an interesting feature, with the development of protonic conduction on the surface and more bulk-like water.
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Affiliation(s)
- Zdenek Futera
- Faculty
of Science, University of South Bohemia, Branisovska 1760, 370 05 Ceske Budejovice, Czech Republic
| | - Niall J. English
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
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28
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Duignan TT, Kathmann SM, Schenter GK, Mundy CJ. Toward a First-Principles Framework for Predicting Collective Properties of Electrolytes. Acc Chem Res 2021; 54:2833-2843. [PMID: 34137593 DOI: 10.1021/acs.accounts.1c00107] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Given the universal importance of electrolyte solutions, it is natural to expect that we have a nearly complete understanding of the fundamental properties of these solutions (e.g., the chemical potential) and that we can therefore explain, predict, and control the phenomena occurring in them. In fact, reality falls short of these expectations. But, recent advances in the simulation and modeling of electrolyte solutions indicate that it should soon be possible to make progress toward these goals. In this Account, we will discuss the use of first-principles interaction potentials based in quantum mechanics (QM) to enhance our understanding of electrolyte solutions. Specifically, we will focus on the use of quantum density functional theory (DFT) combined with molecular dynamics simulation (DFT-MD) as the foundation for our approach. The overarching concept is to understand and accurately reproduce the balance between local or short-ranged (SR) structural details and long-range (LR) correlations, allowing the prediction of the thermodynamics of both single ions in solution as well as the collective interactions characterized by activity/osmotic coefficients. In doing so, relevant collective motions and driving forces characterized by chemical potentials can be determined.In this Account, we will make the case that understanding electrolyte solutions requires a faithful QM representation of the SR nature of the ion-ion, ion-water, and water-water interactions. However, the number of molecules that is required for collective behavior makes the direct application of high-level QM methods that contain the best SR physics untenable, making methods that balance accuracy and efficiency a practical goal. Alternatives such as continuum solvent models (CSMs) and empirically based classical molecular dynamics have been extensively employed to resolve this problem but without yet overcoming the fundamental issue of SR accuracy. We will demonstrate that accurately describing the SR interaction is imperative for predicting both intrinsic properties, namely, at infinite dilution, and collective properties of electrolyte solutions.DFT has played an important role in our understanding of condensed phase systems, e.g., bulk liquid water, the air-water interface, ions in bulk, and at the air-water interface. This approach holds huge promise to provide benchmark calculations of electrolyte solution properties that will allow for the development and improvement of more efficient methods, as well as an enhanced understanding of fundamental phenomena. However, the standard protocol using the generalized gradient approximation with van der Waals (vdW) correction requires improvement in order to achieve a high level of quantitative accuracy. Simply simulating with higher level DFT functionals may not be the best route considering the significant computational cost. Alternative methods of incorporating information from higher levels of QM should be explored; e.g., using force matching techniques on small clusters, where high level benchmark calculations are possible, to develop ideal correction terms to the DFT functional is a promising possibility. We argue that DFT with statistical mechanics is becoming an increasingly useful framework enabling the prediction of collective electrolyte properties.
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Affiliation(s)
- Timothy T. Duignan
- School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane 4072, Australia
| | - Shawn M. Kathmann
- Physical Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Gregory K. Schenter
- Physical Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Christopher J. Mundy
- Physical Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
- Affiliate Professor, Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
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Adel T, Ng KC, Vazquez de Vasquez MG, Velez-Alvarez J, Allen HC. Insight into the Ionizing Surface Potential Method and Aqueous Sodium Halide Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7863-7874. [PMID: 34152764 DOI: 10.1021/acs.langmuir.1c00465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Complementing the microscopic picture of the surface structure of electrolyte solutions set out by previous theoretical and experimental studies, the ionizing surface potential technique offers a unique approach to quantifying the impact of aqueous inorganic ions upon the interfacial electric field of the air-aqueous interface. In this Feature Article, we review the vulnerability of theoretical and empirically derived χwater values as a normative reference for aqueous ion surface potentials. Instead, we recognize and evaluate aqueous ion surface potentials relative to well-known ionic surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). Additionally, we also explore factors that impact the magnitude of the measured surface potentials using the ionizing method, particularly in the type of reference electrode and ionizing gas environment. With potential measurements of sodium halide solutions, we show that iodide has a dominant effect on the air-aqueous electric field. Compared to chloride and bromide, iodide is directly observed with a net negatively charged surface electric field at all salt concentrations measured (0.2 to 3.0 mol/kg water). Also, above the 2 M region, bromide is observed with a net negatively charged surface. Although several scenarios contribute to this effect, it is most likely due to the surface enrichment of bromide and iodide. While the results of this study are pertinent to determining the specific interfacial reactivity of aqueous halides, these anions seldom transpire as single-halide systems in the natural environment. Therefore, we also provide an outlook on future research concerning surface potential methods and more complex aqueous electrolyte systems.
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Affiliation(s)
- Tehseen Adel
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Ka Chon Ng
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Maria G Vazquez de Vasquez
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Juan Velez-Alvarez
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Heather C Allen
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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30
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Sinopoli A, Abotaleb A, Pietrucci F, Gladich I. Stability of a Monoethanolamine-CO 2 Zwitterion at the Vapor/Liquid Water Interface: Implications for Low Partial Pressure Carbon Capture Technologies. J Phys Chem B 2021; 125:4890-4897. [PMID: 33885318 DOI: 10.1021/acs.jpcb.1c01661] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The need to chemically convert CO2 at the interface of aqueous amine solutions has become particularly relevant for the development and the broad distribution of cost-effective and near-future devices for direct air capture working at low (e.g., ambient) partial pressure. Here, we have determined the stability of a CO2-monoethanolamine zwitterion and its chemical conversion into carbamate at the vapor/liquid water interface by first-principles molecular dynamics simulations coupled with a recently introduced enhanced sampling technique. Contrary to the bulk water case, our results show that both the zwitterion and carbamate ions are poorly stable at the vapor/amine aqueous interface, further stating the differences between the homogeneous and heterogeneous CO2 chemical conversion. The design of novel and cost-effective capture systems, such as those offered by amine-based scrubbing solutions, working at low (e.g., ambient) CO2 partial pressure should explore the use of novel solvents, different from aqueous mixtures, to overcome the limits of the current absorbents.
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Affiliation(s)
- Alessandro Sinopoli
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34410, Doha, Qatar
| | - Ahmed Abotaleb
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34410, Doha, Qatar
| | - Fabio Pietrucci
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IMPMC, 75005 Paris, France
| | - Ivan Gladich
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34410, Doha, Qatar
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31
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Cui H, Zhang L, Eltoukhy L, Jiang Q, Korkunç SK, Jaeger KE, Schwaneberg U, Davari MD. Enzyme Hydration Determines Resistance in Organic Cosolvents. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03233] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Haiyang Cui
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
| | - Lingling Zhang
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
| | - Lobna Eltoukhy
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
| | - Qianjia Jiang
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
| | - Seval Kübra Korkunç
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Wilhelm Johnen Strasse, Jülich 52426, Germany
- Institute of Bio-and Geosciences IBG 1: Biotechnology, Forschungszentrum Jülich GmbH, Wilhelm Johnen Strasse, Jülich 52426, Germany
| | - Ulrich Schwaneberg
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, Aachen 52074, Germany
| | - Mehdi D. Davari
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany
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Absolute ion hydration free energy scale and the surface potential of water via quantum simulation. Proc Natl Acad Sci U S A 2020; 117:30151-30158. [PMID: 33203676 DOI: 10.1073/pnas.2017214117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
With a goal of determining an absolute free energy scale for ion hydration, quasi-chemical theory and ab initio quantum mechanical simulations are employed to obtain an accurate value for the bulk hydration free energy of the Na+ ion. The free energy is partitioned into three parts: 1) the inner-shell or chemical contribution that includes direct interactions of the ion with nearby waters, 2) the packing free energy that is the work to produce a cavity of size λ in water, and 3) the long-range contribution that involves all interactions outside the inner shell. The interfacial potential contribution to the free energy resides in the long-range term. By averaging cation and anion data for that contribution, cumulant terms of all odd orders in the electrostatic potential are removed. The computed total is then the bulk hydration free energy. Comparison with the experimentally derived real hydration free energy produces an effective surface potential of water in the range -0.4 to -0.5 V. The result is consistent with a variety of experiments concerning acid-base chemistry, ion distributions near hydrophobic interfaces, and electric fields near the surface of water droplets.
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Gladich I, Abotaleb A, Sinopoli A. Tuning CO 2 Capture at the Gas/Amine Solution Interface by Changing the Solvent Polarity. J Phys Chem B 2020; 124:10245-10256. [PMID: 33140965 DOI: 10.1021/acs.jpcb.0c06340] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbon dioxide scrubbing by aqueous amine solution is considered as a promising technology for post-combustion CO2 capture, while mitigating climate change. The lack of physicochemical details for this process, especially at the interface between the gas and the condensed phase, limits our capability in designing novel and more cost-effective scrubbing systems. Here, we present classical and first-principles molecular dynamics results on CO2 capture at the gas/amine solution interfaces using solvents of different polarities. Even if it is apolar, carbon dioxide is absorbed at the gas/monoethanolamine (MEA) aqueous solution interface, forming stable and interfacial [CO2·MEA] complexes, which are the first reaction intermediate toward the chemical conversion of CO2 to carbamate ions. We report that the stability of the interfacial [CO2·MEA] precomplex depends on the nature and polarity of the solution, as well as on the conformer population of MEA. By changing the polarity of the solvent, using chloroform, we observed a shift in the interfacial MEA population toward conformers that form more stable [CO2·MEA] complexes and, at the same time, a further stabilization of the complex induced by the solvent environment. Thus, while lowering the polarity of the solvent could decrease the solubility of MEA, at the same time, it favors conformers that are more prone to CO2 capture and mineralization. The results presented here offer a theoretical framework that helps in designing novel and more cost-effective solvents for CO2 scrubbing systems, while shedding further light on the intrinsic reaction mechanisms of interfacial environments in general.
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Affiliation(s)
- Ivan Gladich
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Ahmed Abotaleb
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Alessandro Sinopoli
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
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Nauruzbayeva J, Sun Z, Gallo A, Ibrahim M, Santamarina JC, Mishra H. Electrification at water-hydrophobe interfaces. Nat Commun 2020; 11:5285. [PMID: 33082321 PMCID: PMC7576844 DOI: 10.1038/s41467-020-19054-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 09/28/2020] [Indexed: 11/23/2022] Open
Abstract
The mechanisms leading to the electrification of water when it comes in contact with hydrophobic surfaces remains a research frontier in chemical science. A clear understanding of these mechanisms could, for instance, aid the rational design of triboelectric generators and micro- and nano-fluidic devices. Here, we investigate the origins of the excess positive charges incurred on water droplets that are dispensed from capillaries made of polypropylene, perfluorodecyltrichlorosilane-coated glass, and polytetrafluoroethylene. Results demonstrate that the magnitude and sign of electrical charges vary depending on: the hydrophobicity/hydrophilicity of the capillary; the presence/absence of a water reservoir inside the capillary; the chemical and physical properties of aqueous solutions such as pH, ionic strength, dielectric constant and dissolved CO2 content; and environmental conditions such as relative humidity. Based on these results, we deduce that common hydrophobic materials possess surface-bound negative charge. Thus, when these surfaces are submerged in water, hydrated cations form an electrical double layer. Furthermore, we demonstrate that the primary role of hydrophobicity is to facilitate water-substrate separation without leaving a significant amount of liquid behind. These results advance the fundamental understanding of water-hydrophobe interfaces and should translate into superior materials and technologies for energy transduction, electrowetting, and separation processes, among others. Electrification of water upon contact with hydrophobic surfaces is a ubiquitous but poorly understood phenomenon. Here, the authors pinpoint the factors responsible for the excess positive charge carried by water droplets dispensed from hydrophobic capillaries, thereby answering some outstanding questions and raising new ones.
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Affiliation(s)
- Jamilya Nauruzbayeva
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Zhonghao Sun
- King Abdullah University of Science and Technology, Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC), Division of Physical Science and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Adair Gallo
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Mahmoud Ibrahim
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - J Carlos Santamarina
- King Abdullah University of Science and Technology, Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC), Division of Physical Science and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Himanshu Mishra
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia.
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35
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Maldonado AM, Basdogan Y, Berryman JT, Rempe SB, Keith JA. First-principles modeling of chemistry in mixed solvents: Where to go from here? J Chem Phys 2020; 152:130902. [PMID: 32268733 DOI: 10.1063/1.5143207] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mixed solvents (i.e., binary or higher order mixtures of ionic or nonionic liquids) play crucial roles in chemical syntheses, separations, and electrochemical devices because they can be tuned for specific reactions and applications. Apart from fully explicit solvation treatments that can be difficult to parameterize or computationally expensive, there is currently no well-established first-principles regimen for reliably modeling atomic-scale chemistry in mixed solvent environments. We offer our perspective on how this process could be achieved in the near future as mixed solvent systems become more explored using theoretical and computational chemistry. We first outline what makes mixed solvent systems far more complex compared to single-component solvents. An overview of current and promising techniques for modeling mixed solvent environments is provided. We focus on so-called hybrid solvation treatments such as the conductor-like screening model for real solvents and the reference interaction site model, which are far less computationally demanding than explicit simulations. We also propose that cluster-continuum approaches rooted in physically rigorous quasi-chemical theory provide a robust, yet practical, route for studying chemical processes in mixed solvents.
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Affiliation(s)
- Alex M Maldonado
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yasemin Basdogan
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Joshua T Berryman
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg City, Luxembourg
| | - Susan B Rempe
- Center for Computational Biology and Biophysics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - John A Keith
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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36
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Ghaani MR, Kusalik PG, English NJ. Massive generation of metastable bulk nanobubbles in water by external electric fields. SCIENCE ADVANCES 2020; 6:eaaz0094. [PMID: 32284977 PMCID: PMC7124953 DOI: 10.1126/sciadv.aaz0094] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/26/2019] [Indexed: 05/21/2023]
Abstract
Nanobubbles (NBs) are nanoscopic gaseous domains than can exist on solid surfaces or in bulk liquids. They have attracted substantial attention due to their long-time (meta)stability and a high potential for real-world applications. Using an approach not previously investigated, we exploit surface-electrostatic NB formation and stabilization via application of external electric fields in gas-liquid systems, with the marked result of massively increased gas uptake into the liquid in NB form. The de facto gas solubility enhancement (over many months) ranges from 2.5-fold for oxygen to 30-fold for methane vis-à-vis respective Henry's law values for gas solubility; the more hydrophobic the gas, the more spectacular the increase. Molecular dynamics simulations reveal that the origin of NBs' movement lies in dielectrophoresis, while substantial NB stabilization arises from a surface-polarization interaction.
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Affiliation(s)
- Mohammad Reza Ghaani
- School of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
- Corresponding author. (M.R.G.); (N.J.E.)
| | - Peter G. Kusalik
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada
| | - Niall J. English
- School of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
- Corresponding author. (M.R.G.); (N.J.E.)
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37
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Yesibolati MN, Laganà S, Sun H, Beleggia M, Kathmann SM, Kasama T, Mølhave K. Mean Inner Potential of Liquid Water. PHYSICAL REVIEW LETTERS 2020; 124:065502. [PMID: 32109081 DOI: 10.1103/physrevlett.124.065502] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/20/2019] [Accepted: 12/23/2019] [Indexed: 06/10/2023]
Abstract
Improving our experimental and theoretical knowledge of electric potentials at liquid-solid boundaries is essential to achieve a deeper understanding of the driving forces behind interfacial processes. Electron holography has proved successful in probing solid-solid interfaces but requires knowledge of the materials' mean inner potential (MIP, V_{0}), which is a fundamental bulk material property. Combining off-axis electron holography with liquid phase transmission electron microscopy (LPTEM), we provide the first quantitative MIP determination of liquid water V_{0}=+4.48±0.19 V. This value is larger than most theoretical predictions, and to explain the disagreement we assess the dominant factors needed in quantum simulations of liquid water. A precise MIP lays the foundations for nanoscale holographic potential measurements in liquids, and provides a benchmark to improve quantum mechanical descriptions of aqueous systems and their interfaces in, e.g., electrochemistry, solvation processes, and spectroscopy.
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Affiliation(s)
- Murat Nulati Yesibolati
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Simone Laganà
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Hongyu Sun
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Marco Beleggia
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Shawn M Kathmann
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA
| | - Takeshi Kasama
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Kristian Mølhave
- DTU Nanolab, National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Building 307, 2800 Kgs. Lyngby, Denmark
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38
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Duignan TT, Zhao XS. The Born model can accurately describe electrostatic ion solvation. Phys Chem Chem Phys 2020; 22:25126-25135. [DOI: 10.1039/d0cp04148c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solvation free energies of ions in water are consistent with the Born linear response model if the centre on which the ion–water repulsion force acts is moved from the oxygen atom towards the hydrogens.
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Affiliation(s)
- Timothy T. Duignan
- School of Chemical Engineering
- The University of Queensland
- St Lucia
- Australia
| | - X. S. Zhao
- School of Chemical Engineering
- The University of Queensland
- St Lucia
- Australia
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39
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40
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Houriez C, Réal F, Vallet V, Mautner M, Masella M. Ion hydration free energies and water surface potential in water nano drops: The cluster pair approximation and the proton hydration Gibbs free energy in solution. J Chem Phys 2019; 151:174504. [PMID: 31703526 DOI: 10.1063/1.5109777] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We estimate both single ion hydration Gibbs free energies in water droplets, comprising from 50 to 1000 molecules, and water/vacuum surface potentials in pure water droplets comprising up to 10 000 molecules. We consider four ions, namely, Li+, NH4 +, F-, and Cl-, and we model their hydration process and water/water interactions using polarizable force fields based on an induced point dipole approach. We show both ion hydration Gibbs free energies and water surface potentials to obey linear functions of the droplet radius as soon as droplets comprising a few hundred water molecules. Moreover, we also show that the differences in anion/cation hydration Gibbs free energies in droplets obey a different regime in large droplets than in small clusters comprising no more than six water molecules, in line with the earlier results computed from standard additive point charge force fields. Hence, both point charge and more sophisticated induced point dipole molecular modeling approaches suggest that methods considering only the thermodynamical properties of small ion/water clusters to estimate the absolute proton hydration Gibbs free energy in solution are questionable. In particular, taking into account the data of large ion/water droplets may yield a proton hydration Gibbs free energy in solution value to be shifted by several kBT units compared to small clusters-based approaches.
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Affiliation(s)
- Céline Houriez
- MINES ParisTech, PSL Research University, CTP - Centre Thermodynamique des Procédés, 35 rue Saint-Honoré, 77300 Fontainebleau, France
| | - Florent Réal
- Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France
| | - Valérie Vallet
- Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France
| | - Michael Mautner
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006, USA and Department of Chemistry, University of Canterbury, Christchurch 8001, New Zealand
| | - Michel Masella
- Laboratoire de Biologie Structurale et Radiobiologie, Service de Bioénergétique, Biologie Structurale et Mécanismes, Institut Joliot, CEA Saclay, F-91191 Gif sur Yvette Cedex, France
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41
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Doyle CC, Shi Y, Beck TL. The Importance of the Water Molecular Quadrupole for Estimating Interfacial Potential Shifts Acting on Ions Near the Liquid–Vapor Interface. J Phys Chem B 2019; 123:3348-3358. [DOI: 10.1021/acs.jpcb.9b01289] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carrie C. Doyle
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Yu Shi
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Thomas L. Beck
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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42
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Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2040068] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Using neodymium ring magnets (0.5–0.65 T), the experiments on the magnetic field (MF) effects on water evaporation rate and surface tension were performed at room temperature (22–24 °C). In accordance with the literature data, the enhanced evaporation rates were observed in the experiments conducted in a period of several days or weeks. However, the evaporated amounts of water (up to 440 mg over 150 min) in particular experiments differed. The evaporated amounts depended partially on which pole of the ring magnet was directed up. The relatively strong MF (0.65 T) caused a slight decrease in surface tension (−2.11 mN/m) which lasted longer than 60 min and the memory effect vanished slowly. The surface tension data reduced by the MF action are reported in the literature, although contrary results can be also found. The observed effects can be explained based on literature data of molecular simulations and the suggestion that MF affects the hydrogen bonds of intra- and inter-clusters of water molecules, possibly even causing breakage some of them. The Lorentz force influence is also considered. These mechanisms are discussed in the paper.
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Prasetyo N, Hünenberger PH, Hofer TS. Single-Ion Thermodynamics from First Principles: Calculation of the Absolute Hydration Free Energy and Single-Electrode Potential of Aqueous Li + Using ab Initio Quantum Mechanical/Molecular Mechanical Molecular Dynamics Simulations. J Chem Theory Comput 2018; 14:6443-6459. [PMID: 30284829 DOI: 10.1021/acs.jctc.8b00729] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A recently proposed thermodynamic integration (TI) approach formulated in the framework of quantum mechanical/molecular mechanical molecular dynamics (QM/MM MD) simulations is applied to study the structure, dynamics, and absolute intrinsic hydration free energy Δs GM+,wat◦ of the Li+ ion at a correlated ab initio level of theory. Based on the results, standard values (298.15 K, ideal gas at 1 bar, ideal solute at 1 molal) for the absolute intrinsic hydration free energy [Formula: see text] of the proton, the surface electric potential jump χwat◦ upon entering bulk water, and the absolute single-electrode potential [Formula: see text] of the reference hydrogen electrode are calculated to be -1099.9 ± 4.2 kJ·mol-1, 0.13 ± 0.08 V, and 4.28 ± 0.04 V, respectively, in excellent agreement with the standard values recommended by Hünenberger and Reif on the basis of an extensive evaluation of the available experimental data (-1100 ± 5 kJ·mol-1, 0.13 ± 0.10 V, and 4.28 ± 0.13 V). The simulation results for Li+ are also compared to those for Na+ and K+ from a previous study in terms of relative hydration free energies ΔΔs GM+,wat◦ and relative electrode potentials [Formula: see text]. The calculated values are found to agree extremely well with the experimental differences in standard conventional hydration free energies ΔΔs GM+,wat• and redox potentials [Formula: see text]. The level of agreement between simulation and experiment, which is quantitative within error bars, underlines the substantial accuracy improvement achieved by applying a highly demanding QM/MM approach at the resolution-of-identity second-order Møller-Plesset perturbation (RIMP2) level over calculations relying on purely molecular mechanical or density functional theory (DFT) descriptions. A detailed analysis of the structural and dynamical properties of the Li+ hydrate indicates that a correct description of the solvation structure and dynamics is achieved as well at this level of theory. Consideration of the QM/MM potential-energy components also shows that the partitioning into QM and MM zones does not induce any significant energetic artifact for the system considered.
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Affiliation(s)
- Niko Prasetyo
- Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria.,Austria-Indonesia Centre (AIC) for Computational Chemistry , Universitas Gadjah Mada , Sekip Utara , Yogyakarta 55281 , Indonesia.,Department of Chemistry, Faculty of Mathematics and Natural Sciences , Universitas Gadjah Mada , Sekip Utara , Yogyakarta 55281 , Indonesia
| | - Philippe H Hünenberger
- Laboratorium für Physikalische Chemie , ETH Zürich, ETH-Hönggerberg , HCI Building , CH-8093 Zürich , Switzerland
| | - Thomas S Hofer
- Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
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Chibowski E, Szcześ A. Magnetic water treatment-A review of the latest approaches. CHEMOSPHERE 2018; 203:54-67. [PMID: 29605749 DOI: 10.1016/j.chemosphere.2018.03.160] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 02/22/2018] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Understanding of magnetic field (MF) effects observed during and after its action on water and aqueous solutions is still a controversial issue although the effects have been reported for at least half of century. The purpose of this paper was a brief review of the literature which deals with the magnetic force treatment effects. However, it is especially focused on the latest approaches, published mostly in the last decade which have developed our understanding of the mechanisms accompanying the field action. Generally, the changes in water structure via hydrogen bonding changes, as well as in intraclusters and between interclusters were taken into account, but the most remarkable progress was achieved in 2012 by Coey who applied the non-classical theory of nucleation mechanism of the formation of dynamically ordered liquid like oxyanion polymers (DOLLOP) to explain the magnetic field action. His criterion for the magnetic field effect to occur was experimentally verified. It was also proved that the gradient of the magnetic field is more important than the magnetic field strength itself. Some interesting approaches explaining an enhanced evaporation rate of water by MF are also discussed. More experimental results are needed for further verification of the DOLLOP theory to achieve a more profound understanding of the MF effects.
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Affiliation(s)
- Emil Chibowski
- Department of Physical Chemistry - Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
| | - Aleksandra Szcześ
- Department of Physical Chemistry - Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
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Pollard TP, Beck TL. Re-examining the tetraphenyl-arsonium/tetraphenyl-borate (TATB) hypothesis for single-ion solvation free energies. J Chem Phys 2018; 148:222830. [DOI: 10.1063/1.5024209] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Travis P. Pollard
- Electrochemistry Branch, US Army Research Laboratory, Adelphi, Maryland 20852, USA
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, USA
| | - Thomas L. Beck
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, USA
- Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA
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46
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Hofer TS, Hünenberger PH. Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration. J Chem Phys 2018; 148:222814. [DOI: 10.1063/1.5000799] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Thomas S. Hofer
- Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry, Centre for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
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Prozorov T, Almeida TP, Kovács A, Dunin-Borkowski RE. Off-axis electron holography of bacterial cells and magnetic nanoparticles in liquid. J R Soc Interface 2018; 14:rsif.2017.0464. [PMID: 29021160 DOI: 10.1098/rsif.2017.0464] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/18/2017] [Indexed: 12/19/2022] Open
Abstract
The mapping of electrostatic potentials and magnetic fields in liquids using electron holography has been considered to be unrealistic. Here, we show that hydrated cells of Magnetospirillum magneticum strain AMB-1 and assemblies of magnetic nanoparticles can be studied using off-axis electron holography in a fluid cell specimen holder within the transmission electron microscope. Considering that the holographic object and reference wave both pass through liquid, the recorded electron holograms show sufficient interference fringe contrast to permit reconstruction of the phase shift of the electron wave and mapping of the magnetic induction from bacterial magnetite nanocrystals. We assess the challenges of performing in situ magnetization reversal experiments using a fluid cell specimen holder, discuss approaches for improving spatial resolution and specimen stability, and outline future perspectives for studying scientific phenomena, ranging from interparticle interactions in liquids and electrical double layers at solid-liquid interfaces to biomineralization and the mapping of electrostatic potentials associated with protein aggregation and folding.
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Affiliation(s)
- Tanya Prozorov
- Division of Materials Sciences and Engineering, Ames Laboratory, Ames, IA 50011, USA
| | - Trevor P Almeida
- Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
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48
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Ohno PE, Wang HF, Paesani F, Skinner JL, Geiger FM. Second-Order Vibrational Lineshapes from the Air/Water Interface. J Phys Chem A 2018; 122:4457-4464. [PMID: 29665333 DOI: 10.1021/acs.jpca.8b02802] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We explore by means of modeling how absorptive-dispersive mixing between the second- and third-order terms modifies the imaginary χtotal(2) responses from air/water interfaces under conditions of varying charge densities and ionic strength. To do so, we use published Im(χ(2)) and χ(3) spectra of the neat air/water interface that were obtained either from computations or experiments. We find that the χtotal(2) spectral lineshapes corresponding to experimentally measured spectra contain significant contributions from both interfacial χ(2) and bulk χ(3) terms at interfacial charge densities equivalent to less than 0.005% of a monolayer of water molecules, especially in the 3100 to 3300 cm-1 frequency region. Additionally, the role of short-range static dipole potentials is examined under conditions mimicking brine. Our results indicate that surface potentials, if indeed present at the air/water interface, manifest themselves spectroscopically in the tightly bonded H-bond network observable in the 3200 cm-1 frequency range.
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Affiliation(s)
- Paul E Ohno
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Hong-Fei Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , Shanghai 200433 , China
| | - Francesco Paesani
- Departments of Chemistry and Biochemistry , Materials Science and Engineering , and San Diego Supercomputer Center , University of California, San Diego , Urey Hall 6218, 9500 Gilman Drive , La Jolla , California 92093-0314 , United States
| | - James L Skinner
- Eckhardt Research Center , Institute for Molecular Engineering , Room 205, 5640 South Ellis Avenue , Chicago , Illinois 60637 , United States
| | - Franz M Geiger
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
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Experimentally quantifying anion polarizability at the air/water interface. Nat Commun 2018; 9:1313. [PMID: 29615604 PMCID: PMC5882839 DOI: 10.1038/s41467-018-03598-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/19/2018] [Indexed: 12/22/2022] Open
Abstract
The adsorption of large, polarizable anions from aqueous solution on the air/water interface controls important atmospheric chemistry and is thought to resemble anion adsorption at hydrophobic interfaces generally. While the favourability of adsorption of such ions is clear, quantifying adsorption thermodynamics has proven challenging because it requires accurate description of the structure of the anion and its solvation shell at the interface. In principle anion polarizability offers a structural window, but to the best of our knowledge there has so far been no experimental technique that allowed its characterization with interfacial specificity. Here, we meet this challenge using interface-specific vibrational spectroscopy of Cl–O vibrations of the \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{ClO}}_4^ -$$\end{document}ClO4- anion at the air/water interface and report that the interface breaks the symmetry of the anion, the anisotropy of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{ClO}}_4^ -$$\end{document}ClO4-’s polarizability tensor is more than two times larger than in bulk water and concentration dependent, and concentration-dependent polarizability changes are consistent with correlated changes in surface tension. Understanding anion-specific interactions with hydrophobic interfaces is challenging due to an absence of local structural probes. Here, the authors experimentally quantify the anisotropy of perchlorate’s polarizability at the air/water interface, a window into anion and solvation shell structure.
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50
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Hölzl C, Horinek D. Pressure increases the ice-like order of water at hydrophobic interfaces. Phys Chem Chem Phys 2018; 20:21257-21261. [DOI: 10.1039/c8cp03057j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Ice-like order of water at hydrophobic interfaces is quantified on different length scales based on molecular dynamics simulations.
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Affiliation(s)
- Christoph Hölzl
- Institut für Physikalische und Theoretische Chemie
- Universität Regensburg
- 93040 Regensburg
- Germany
| | - Dominik Horinek
- Institut für Physikalische und Theoretische Chemie
- Universität Regensburg
- 93040 Regensburg
- Germany
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