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Perets EA, Konstantinovsky D, Santiago T, Videla PE, Tremblay M, Velarde L, Batista VS, Hammes-Schiffer S, Yan ECY. Beyond the "spine of hydration": Chiral SFG spectroscopy detects DNA first hydration shell and base pair structures. J Chem Phys 2024; 161:095104. [PMID: 39230381 PMCID: PMC11377083 DOI: 10.1063/5.0220479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Accepted: 08/06/2024] [Indexed: 09/05/2024] Open
Abstract
Experimental methods capable of selectively probing water at the DNA minor groove, major groove, and phosphate backbone are crucial for understanding how hydration influences DNA structure and function. Chiral-selective sum frequency generation spectroscopy (chiral SFG) is unique among vibrational spectroscopies because it can selectively probe water molecules that form chiral hydration structures around biomolecules. However, interpreting chiral SFG spectra is challenging since both water and the biomolecule can produce chiral SFG signals. Here, we combine experiment and computation to establish a theoretical framework for the rigorous interpretation of chiral SFG spectra of DNA. We demonstrate that chiral SFG detects the N-H stretch of DNA base pairs and the O-H stretch of water, exclusively probing water molecules in the DNA first hydration shell. Our analysis reveals that DNA transfers chirality to water molecules only within the first hydration shell, so they can be probed by chiral SFG spectroscopy. Beyond the first hydration shell, the electric field-induced water structure is symmetric and, therefore, precludes chiral SFG response. Furthermore, we find that chiral SFG can differentiate chiral subpopulations of first hydration shell water molecules at the minor groove, major groove, and phosphate backbone. Our findings challenge the scientific perspective dominant for more than 40 years that the minor groove "spine of hydration" is the only chiral water structure surrounding the DNA double helix. By identifying the molecular origins of the DNA chiral SFG spectrum, we lay a robust experimental and theoretical foundation for applying chiral SFG to explore the chemical and biological physics of DNA hydration.
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Affiliation(s)
- Ethan A Perets
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Daniel Konstantinovsky
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Ty Santiago
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Pablo E Videla
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Matthew Tremblay
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Luis Velarde
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Elsa C Y Yan
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
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2
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Tetteh N, Parshotam S, Gibbs JM. Separating Hofmeister Trends in Stern and Diffuse Layers at a Charged Interface. J Phys Chem Lett 2024; 15:9113-9121. [PMID: 39206708 DOI: 10.1021/acs.jpclett.4c01792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Understanding the role of pH and ions on the electrical double layer (EDL) at charged mineral oxide/aqueous interfaces remains crucial in modeling environmental and industrial processes. Yet the simultaneous contribution of pH and specific ion effects (SIEs) on the different layers of the EDL remains unknown. Here, we utilize zeta potential measurements, vibrational sum frequency generation, and the maximum entropy method to ascertain the detailed structure of the Stern and diffuse regions of the EDL at the silica/water interface with varying pH values for different alkali chlorides. Both at pH 2, when the surface is nearly neutral, and at pH 12, when the surface is highly charged, we observe that Li+ and Na+ disrupt while Cs+ enhances existing water structures within the Stern layer. Moreover, the SIE trends for the diffuse and Stern layers are opposite to one another at pH 2 (in the amount of ordered water) and at pH 12 (in the amount of net oriented water). Finally, we observe an inversion in Hofmeister (SIE) trends at low and high pH in the zeta that impacts the diffuse layer structure. These results indicate that SIEs play critical yet separable roles in governing both the electrostatic and water-structuring capabilities of the EDL.
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Affiliation(s)
- Nathaniel Tetteh
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Shyam Parshotam
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Julianne M Gibbs
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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3
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Zhang H, Liu D, Zhang J, Adams E, Gong J, Li W, Wang B, Liu X, Yang R, Wei F, Allen HC. GMP affected assembly behaviors of phosphatidylethanolamine monolayers elucidated by multi-resolved SFG-VS and BAM. Colloids Surf B Biointerfaces 2024; 241:113995. [PMID: 38870647 DOI: 10.1016/j.colsurfb.2024.113995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 05/18/2024] [Accepted: 05/26/2024] [Indexed: 06/15/2024]
Abstract
The interaction between nucleotide molecules and lipid molecules plays important roles in cell activities, but the molecular mechanism is very elusive. In the present study, a small but noticeable interaction between the negatively charged phosphatidylethanolamine (PE) and Guanosine monophosphate (GMP) molecules was observed from the PE monolayer at the air/water interface. As shown by the sum frequency generation (SFG) spectra and Pi-A isotherm of the PE monolayer, the interaction between the PE and GMP molecules imposes very small changes to the PE molecules. However, the Brewster angle microscopy (BAM) technique revealed that the assembly conformations of PE molecules are significantly changed by the adsorption of GMP molecules. By comparing the SFG spectra of PE monolayers after the adsorption of GMP, guanosine and guanine, it is also shown that the hydrogen bonding effect plays an important role in the nucleotide-PE interactions. These results provide fundamental insight into the structure changes during the nucleotide-lipid interaction, which may shed light on the molecular mechanism of viral infection, DNA drug delivery, and cell membrane curvature control in the brain or neurons.
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Affiliation(s)
- Hongjuan Zhang
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Dongqi Liu
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Jiawei Zhang
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Ellen Adams
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - Jingjing Gong
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Wenhui Li
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Bing Wang
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Xueqing Liu
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Renqiang Yang
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
| | - Feng Wei
- School of Optoelectronic Materials and Technology, & Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China.
| | - Heather C Allen
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
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4
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Schneck E, Reed J, Seki T, Nagata Y, Kanduč M. Experimental and simulation-based characterization of surfactant adsorption layers at fluid interfaces. Adv Colloid Interface Sci 2024; 331:103237. [PMID: 38959812 DOI: 10.1016/j.cis.2024.103237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 06/10/2024] [Accepted: 06/13/2024] [Indexed: 07/05/2024]
Abstract
Adsorption of surfactants to fluid interfaces occurs in numerous technological and daily-life contexts. The coverage at the interface and other properties of the formed adsorption layers determine the performance of a surfactant with regard to the desired application. Given the importance of these applications, there is a great demand for the comprehensive characterization and understanding of surfactant adsorption layers. In this review, we provide an overview of suitable experimental and simulation-based techniques and review the literature in which they were used for the investigation of surfactant adsorption layers. We come to the conclusion that, while these techniques have been successfully applied to investigate Langmuir monolayers of water-insoluble surfactants, their application to the study of Gibbs adsorption layers of water-soluble surfactants has not been fully exploited. Finally, we emphasize the great potential of these methods in providing a deeper understanding of the behavior of soluble surfactants at interfaces, which is crucial for optimizing their performance in various applications.
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Affiliation(s)
- Emanuel Schneck
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Joshua Reed
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany
| | - Takakazu Seki
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561 Aomori, Japan
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | - Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
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5
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Bregnhøj M, Golbek TW, Madzharova F, Weidner T. De Novo Design and Characterization of Amphiphilic Peptides with Basic Side Chains for Tailored Interfacial Chemistries. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39213639 DOI: 10.1021/acs.langmuir.4c01654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Lysine-leucine (LK) peptides have been used as model systems and platforms for 2D material design for decades. LK peptides are amphiphilic sequences designed to bind and fold at hydrophobic surfaces through hydrophobic leucine side chains and hydrophilic lysine side chains extending into the aqueous subphase. The hydrophobic periodicity of the sequence dictates the secondary structure at the interface. This robust design makes them ideal candidates for controlling interfacial chemistry. This study presents the de novo design and characterization of two novel peptides: LRα14 and LHα14, which substitute lysine with arginine and histidine, respectively, in the helical LKα14 sequence. This modification is intended to expand the LK peptide platform to a new basic interfacial chemistry. We explore the stability of the new LRα14 and LHα14 designs with respect to changes in pH and salt concentration in bulk solution and at the interface using circular dichroism (UV-CD) and vibrational sum-frequency generation spectroscopy, respectively. Notably, the structural stability of the peptides remains unaffected across a wide range of pH and ionic strength values. At the same time, the variation of side-chain chemistry leads to a wide spectrum of interfacial water structures. By extension of the LK platform to include arginine and histidine, this study broadens the toolbox for designing tailored interfacial chemistries with applications in material and biomedical sciences.
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Affiliation(s)
- Mikkel Bregnhøj
- Department of Chemistry, Aarhus University, 8000 Aarhus, Denmark
| | | | - Fani Madzharova
- Department of Chemistry, Aarhus University, 8000 Aarhus, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus, Denmark
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6
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Hore DK. Phase of the second-order susceptibility in vibrational sum frequency generation spectroscopy: Origins, utility, and measurement techniques. J Chem Phys 2024; 161:060902. [PMID: 39132786 DOI: 10.1063/5.0220817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 07/17/2024] [Indexed: 08/13/2024] Open
Abstract
Vibrational sum frequency generation can provide valuable structural information at surfaces and buried interfaces. Relating the measured spectra to the complex-valued second-order susceptibility χ(2) is at the heart of the technique and a requisite step in nearly all subsequent analyses. The magnitude and phase of χ(2) as a function of frequency reveal important information about molecules and materials in regions where centrosymmetry is broken. In this tutorial-style perspective, the origins of the χ(2) phase are first described, followed by the utility of phase determination. Finally, some practical methods of phase extraction are discussed.
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Affiliation(s)
- Dennis K Hore
- Department of Chemistry, University of Victoria, Victoria, British Columbia V8W 3V6, Canada and Department of Computer Science, University of Victoria, Victoria, British Columbia V8W 3V6, Canada
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7
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Smirnov KS. Effects of Surface Charge Distribution and Electrolyte Ions on the Nonlinear Spectra of Model Solid-Water Interfaces. Molecules 2024; 29:3758. [PMID: 39202839 PMCID: PMC11356812 DOI: 10.3390/molecules29163758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 07/31/2024] [Accepted: 08/01/2024] [Indexed: 09/03/2024] Open
Abstract
Molecular dynamics simulations of model charged solid/water interfaces were carried out to provide insight about the relationship between the second-order nonlinear susceptibility χ(2) and the structure of the interfacial water layer. The results of the calculations reveal that the density fluctuations of water extend to about 12 Å from the surface regardless of the system, while the orientational ordering of molecules is long-ranged and is sensitive to the presence of electrolytes. The charge localization on the surface was found to affect only the high-frequency part of the Im[χ(2)] spectrum, and the addition of salt has very little effect on the spectrum of the first water layer. For solid/neat water interfaces, the spectroscopically active part of the liquid phase has a thickness largely exceeding the region of density fluctuations, and this long-ranged nonlinear activity is mediated by the electric field of the molecules. The electrolyte ions and their hydration shells act in a destructive way on the molecular field. This effect, combined with the screening of the surface charge by ions, drastically reduces the thickness of the spectroscopic diffuse layer. There is an electrolyte concentration at which the nonlinear response of the diffuse layer is suppressed and the χ(2) spectrum of the interface essentially coincides with that of the first water layer.
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Affiliation(s)
- Konstantin S Smirnov
- Univ. Lille, CNRS, UMR 8516 - LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'Environnement, F-59000 Lille, France
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8
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Huang Z, Roos T, Tong Y, Campen RK. Integration of conventional surface science techniques with surface-sensitive azimuthal and polarization dependent femtosecond-resolved sum frequency generation spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:063903. [PMID: 38842418 DOI: 10.1063/5.0205278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 05/15/2024] [Indexed: 06/07/2024]
Abstract
Experimental insight into the elementary processes underlying charge transfer across interfaces has blossomed with the wide-spread availability of ultra-high vacuum (UHV) setups that allow the preparation and characterization of solid surfaces with well-defined molecular adsorbates over a wide range of temperatures. Within the last 15 years, such insights have extended to charge transfer heterostructures containing solids overlain by one or more atomically thin two dimensional materials. Such systems are of wide potential interest both because they appear to offer a path to separate surface reactivity from bulk chemical properties and because some offer completely novel physics, unrealizable in bulk three dimensional solids. Thick layers of molecular adsorbates or heterostructures of 2D materials generally preclude the use of electrons or atoms as probes. However, with linear photon-in/photon-out techniques, it is often challenging to assign the observed optical response to a particular portion of the interface. We and prior workers have demonstrated that by full characterization of the symmetry of the second order nonlinear optical susceptibility, i.e., the χ(2), in sum frequency generation (SFG) spectroscopy, this problem can be overcome. Here, we describe an UHV system built to allow conventional UHV sample preparation and characterization, femtosecond and polarization resolved SFG spectroscopy, the azimuthal sample rotation necessary to fully describe χ(2) symmetry, and sufficient stability to allow scanning SFG microscopy. We demonstrate these capabilities in proof-of-principle measurements on CO adsorbed on Pt(111) and on the clean Ag(111) surface. Because this setup allows both full characterization of the nonlinear susceptibility and the temperature control and sample preparation/characterization of conventional UHV setups, we expect it to be of great utility in the investigation of both the basic physics and applications of solid, 2D material heterostructures.
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9
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Lu H, Macht M, Rosenberg R, Wiedenbeck E, Lukas M, Qi D, Maltseva D, Zahn D, Cölfen H, Bonn M. Organic Nucleation: Water Rearrangement Reveals the Pathway of Ibuprofen. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307858. [PMID: 38269485 DOI: 10.1002/smll.202307858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/31/2023] [Indexed: 01/26/2024]
Abstract
The organic nucleation of the pharmaceutical ibuprofen is investigated, as triggered by the protonation of ibuprofen sodium salt at elevated pH. The growth and aggregation of nanoscale solution species by Analytical Ultracentrifugation and Molecular Dynamics (MD) simulations is tracked. Both approaches reveal solvated molecules, oligomers, and prenucleation clusters, their size as well as their hydration at different reaction stages. By combining surface-specific vibrational spectroscopy and MD simulations, water interacting with ibuprofen at the air-water interface during nucleation is probed. The results show the structure of water changes upon ibuprofen protonation in response to the charge neutralization. Remarkably, the water structure continues to evolve despite the saturation of protonated ibuprofen at the hydrophobic interface. This further water rearrangement is associated with the formation of larger aggregates of ibuprofen molecules at a late prenucleation stage. The nucleation of ibuprofen involves ibuprofen protonation and their hydrophobic assembly. The results highlight that these processes are accompanied by substantial water reorganization. The critical role of water is possibly relevant for organic nucleation in aqueous environments in general.
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Affiliation(s)
- Hao Lu
- Department of Materials and Textile Engineering, Nanotechnology Research Institute, Jiaxing University, Jiaxing, Zhejiang Province, 314001, P. R. China
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Moritz Macht
- Lehrstuhl für Theoretische Chemie/Computer Chemie Centrum, Friedrich-Alexander Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052, Erlangen, Germany
| | - Rose Rosenberg
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Eduard Wiedenbeck
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Max Lukas
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Daizong Qi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Daria Maltseva
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Dirk Zahn
- Lehrstuhl für Theoretische Chemie/Computer Chemie Centrum, Friedrich-Alexander Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052, Erlangen, Germany
| | - Helmut Cölfen
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
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10
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Liu C, Qin X, Yu C, Guo Y, Zhang Z. Probing the adsorption configuration of methanol at a charged air/aqueous interface using nonlinear spectroscopy. Phys Chem Chem Phys 2024; 26:14336-14344. [PMID: 38699833 DOI: 10.1039/d3cp06317h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Investigating the effects of electrolyte ions on the adsorption configuration of methanol at a charged interface is important for studying the interface structure of electrolyte solutions and the oxidation mechanism of methanol in fuel cells. This study uses sum frequency generation (SFG) and heterodyne-detected second harmonic generation (HD-SHG) to investigate the adsorption configuration of methanol at the air/aqueous interface of 0.1 M NaClO4 solution, 0.1 M HClO4 solution and pure water. The results elucidate that the ion effect in the electrolyte solution affects the interface's charged state and the methanol's adsorption conformation at the interface. The negatively charged surface of the 0.1 M NaClO4 solution and the positively charged surface of the 0.1 M HClO4 solution arise from the corresponding specific ionic effects of the electrolyte solution. The orientation angle of methyl with respect to the surface normal is 43.4° ± 0.1° at the 0.1 M NaClO4 solution surface and 21.5° ± 0.2° at the 0.1 M HClO4 solution surface. Examining these adsorption configurations in detail, we find that at the negatively charged surface the inclined orientation angle (43.4°) of methanol favors the hydroxymethyl production by breaking the C-H bond, while at the positively charged surface the upright orientation angle (21.5°) of methanol promotes the methoxy formation by breaking the O-H bond. These findings not only illuminate the intricate ion effects on small organic molecules but also contribute to a molecular-level comprehension of the oxidation mechanism of methanol at electrode interfaces.
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Affiliation(s)
- Caihe Liu
- Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xujin Qin
- Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Changhui Yu
- Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Guo
- Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Zhang
- Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China
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11
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Raji F, Nguyen NN, Nguyen CV, Nguyen AV. Lead (II) ions enable the ion-specific effects of monovalent anions on the molecular structure and interactions at silica/aqueous interfaces. J Colloid Interface Sci 2024; 662:653-662. [PMID: 38367582 DOI: 10.1016/j.jcis.2024.02.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/07/2024] [Accepted: 02/11/2024] [Indexed: 02/19/2024]
Abstract
HYPOTHESIS The adsorption of heavy metal ions such as Pb(II) onto negatively charged minerals such as silica is expected to alter the structure and the interactions at the silica/aqueous interfaces. Besides the solution pH, the inner-sphere sorption of Pb(II) is expected to regulate the surface charge/potential, hypothesized to control the actions of monovalent anions in the aqueous environment. These complex pictures can be probed directly using surface-sensitive sum-frequency generation (SFG) spectroscopy. EXPERIMENTS The pH-dependent water structure within the double layer at silica/aqueous interfaces under the influence of different ions was examined using SFG. The recorded SFG spectra were deconvoluted into the Stern layer (SL) and diffuse layer (DL) using the maximum entropy method in conjunction with the electrical double-layer theory. FINDINGS Standalone monovalent sodium salts do not exhibit ion-specific effects on the silica/aqueous interfaces. However, the mixture of Pb(II) species and each of these salts display profound ion-specific effects on the structure of silica/aqueous interfaces, indicating the role of Pb(II) as an enabler of the ion-specificity of the investigated monovalent anions. The interesting effect arises from a complex interplay between the physical processes (i.e., electrostatic interactions, screening effects, etc.) and chemical processes such as the hydrolysis of Pb(II) ions, ion complexation, protonation and deprotonation of the surface silanol group.
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Affiliation(s)
- Foad Raji
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Ngoc N Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Cuong V Nguyen
- Department of Water and Environmental Regulation, Joondalup, WA 6027, Australia
| | - Anh V Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
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12
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Wang Y, Tang F, Yu X, Ohto T, Nagata Y, Bonn M. Heterodyne-Detected Sum-Frequency Generation Vibrational Spectroscopy Reveals Aqueous Molecular Structure at the Suspended Graphene/Water Interface. Angew Chem Int Ed Engl 2024; 63:e202319503. [PMID: 38478726 DOI: 10.1002/anie.202319503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Indexed: 04/12/2024]
Abstract
Graphene, a transparent two-dimensional conductive material, has brought extensive new perspectives and prospects to various aqueous technological systems, such as desalination membranes, chemical sensors, energy storage, and energy conversion devices. Yet, the molecular-level details of graphene in contact with aqueous electrolytes, such as water orientation and hydrogen bond structure, remain elusive or controversial. Here, we employ surface-specific heterodyne-detected sum-frequency generation (HD-SFG) vibrational spectroscopy to re-examine the water molecular structure at a freely suspended graphene/water interface. We compare the response from the air/graphene/water system to that from the air/water interface. Our results indicate that theχ y y z 2 ${{\chi }_{yyz}^{\left(2\right)}}$ spectrum recorded from the air/graphene/water system arises from the topmost 1-2 water layers in contact with the graphene, with the graphene itself not generating a significant SFG response. Compared to the air/water interface response, the presence of monolayer graphene weakly affects the interfacial water. Graphene weakly affects the dangling O-H group, lowering its frequency through its interaction with the graphene sheet, and has a very small effect on the hydrogen-bonded O-H group. Molecular dynamics simulations confirm our experimental observation. Our work provides molecular insight into the interfacial structure at a suspended graphene/water interface, relevant to various technological applications of graphene.
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Affiliation(s)
- Yongkang Wang
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Fujie Tang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, 361005, Xiamen, China
- Laboratory of AI for Electrochemistry (AI4EC), IKKEM, 361005, Xiamen, China
| | - Xiaoqing Yu
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Tatsuhiko Ohto
- Graduate School of Engineering, Nagoya University, Nagoya, 464-8603, Japan
| | - Yuki Nagata
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
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13
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Uddin MM, Azam MS, Hore DK. Variable-Angle Surface Spectroscopy Reveals the Water Structure in the Stern Layer at Charged Aqueous Interfaces. J Am Chem Soc 2024; 146:11756-11763. [PMID: 38600700 DOI: 10.1021/jacs.3c14836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
At charged aqueous interfaces, the second-order nonlinear optical response originates from water molecules within the diffuse part of the electrical double layer, which are ordered by the surface field and from water that additionally experiences chemical and physical interactions with the surface in the Stern layer. These two environments can either reinforce or diminish the overall signal and can be disentangled by varying the coherence length of their interaction with external laser fields. Here, we demonstrate a method in which the angle of incidence is varied to afford a significant change in the coherence length. When this technique was applied to the silica-water interface, it was observed that water molecules in the Stern and diffuse layers direct their hydrogen atoms toward the mineral surface at a low ionic strength and neutral pH. A decrease in the signal with increasing ionic strength is attributed to hydrated cation adsorption that competes with free water for deprotonated silanol sites.
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Affiliation(s)
- Md Mosfeq Uddin
- Department of Chemistry, University of Victoria, Victoria V8W 3 V6, British Columbia, Canada
| | - Md Shafiul Azam
- Department of Chemistry, University of Victoria, Victoria V8W 3 V6, British Columbia, Canada
| | - Dennis K Hore
- Department of Chemistry, University of Victoria, Victoria V8W 3 V6, British Columbia, Canada
- Department of Computer Science, University of Victoria, Victoria V8W 3P6, British Columbia, Canada
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14
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Litman Y, Chiang KY, Seki T, Nagata Y, Bonn M. Surface stratification determines the interfacial water structure of simple electrolyte solutions. Nat Chem 2024; 16:644-650. [PMID: 38225269 PMCID: PMC10997511 DOI: 10.1038/s41557-023-01416-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/07/2023] [Indexed: 01/17/2024]
Abstract
The distribution of ions at the air/water interface plays a decisive role in many natural processes. Several studies have reported that larger ions tend to be surface-active, implying ions are located on top of the water surface, thereby inducing electric fields that determine the interfacial water structure. Here we challenge this view by combining surface-specific heterodyne-detected vibrational sum-frequency generation with neural network-assisted ab initio molecular dynamics simulations. Our results show that ions in typical electrolyte solutions are, in fact, located in a subsurface region, leading to a stratification of such interfaces into two distinctive water layers. The outermost surface is ion-depleted, and the subsurface layer is ion-enriched. This surface stratification is a key element in explaining the ion-induced water reorganization at the outermost air/water interface.
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Affiliation(s)
- Yair Litman
- Max Planck Institute for Polymer Research, Mainz, Germany.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
| | | | - Takakazu Seki
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz, Germany.
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15
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Olson AL, Alghamdi AO, Geiger FM. NaCl, MgCl 2, and AlCl 3 Surface Coverages on Fused Silica and Adsorption Free Energies at pH 4 from Nonlinear Optics. J Phys Chem A 2024; 128:2162-2168. [PMID: 38470438 DOI: 10.1021/acs.jpca.4c00514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
We employ amplitude- and phase-resolved second harmonic generation experiments to probe interactions of fused silica:aqueous interfaces with Al3+, Mg2+, and Na+ cations at pH 4 and as a function of metal cation concentration. We quantify the second-order nonlinear susceptibility and the total interfacial potential in the presence and absence of a 10 mM screening electrolyte to understand the influence of charge screening on cation adsorption. Strong cation:surface interactions are observed in the absence of the screening electrolyte. The total potential is then employed to estimate the total number of absorbed cations cm-2. The contributions to the total potential from the bound and mobile charges were separated using Gouy-Chapman-Stern model estimates. All three cations bind fully reversibly, indicating physisorption as the mode of interaction. Of the isotherm models tested, the Kd adsorption model fits the data with binding constants of 3-30 and ∼300 mol-1 for the low (<0.1 mM) and high (0.1-3 mM) concentration regimes, corresponding to adsorption free energies of -13 to -18 and -24 kJ mol-1 at room temperature, respectively. The maximum surface coverages are around 1013 cations cm-2, matching the number of deprotonated silanol groups on silica at pH 4. Clear signs of decoupled Stern and diffuse layer nonlinear optical responses are observed and found to be cation-specific.
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Affiliation(s)
- Alyssa L Olson
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60202, United States
| | - Amani O Alghamdi
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60202, United States
| | - Franz M Geiger
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60202, United States
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16
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de la Puente M, Gomez A, Laage D. Neural Network-Based Sum-Frequency Generation Spectra of Pure and Acidified Water Interfaces with Air. J Phys Chem Lett 2024; 15:3096-3102. [PMID: 38470065 DOI: 10.1021/acs.jpclett.4c00113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The affinity of hydronium ions (H3O+) for the air-water interface is a crucial question in environmental chemistry. While sum-frequency generation (SFG) spectroscopy has been instrumental in indicating the preference of H3O+ for the interface, key questions persist regarding the molecular origin of the SFG spectral changes in acidified water. Here we combine nanosecond long neural network (NN) reactive simulations of pure and acidified water slabs with NN predictions of molecular dipoles and polarizabilities to calculate SFG spectra of long reactive trajectories including proton transfer events. Our simulations show that H3O+ ions cause two distinct changes in phase-resolved SFG spectra: first, a low-frequency tail due to the vibrations of H3O+ and its first hydration shell, analogous to the bulk proton continuum, and second, an enhanced hydrogen-bonded band due to the ion-induced static field polarizing molecules in deeper layers. Our calculations confirm that changes in the SFG spectra of acidic solutions are caused by hydronium ions preferentially residing at the interface.
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Affiliation(s)
- Miguel de la Puente
- PASTEUR, Department of Chemistry, École Normale Supérieur, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Axel Gomez
- PASTEUR, Department of Chemistry, École Normale Supérieur, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Damien Laage
- PASTEUR, Department of Chemistry, École Normale Supérieur, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
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17
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Saak CM, Dreier LB, Machel K, Bonn M, Backus EHG. Biological lipid hydration: distinct mechanisms of interfacial water alignment and charge screening for model lipid membranes. Faraday Discuss 2024; 249:317-333. [PMID: 37795538 DOI: 10.1039/d3fd00117b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
Studying lipid monolayers as model biological membranes, we demonstrate that water molecules interfacing with different model membranes can display preferential orientation for two distinct reasons: due to charges on the membrane, and due to large dipole fields resulting from zwitterionic headgroups. This preferential water orientation caused by the charge or the dipolar field can be effectively neutralized to net-zero water orientation by introducing monolayer counter-charges (i.e. lipids with oppositely charged headgroups). Following the Gouy-Chapman model, the effect of monolayer surface charge on water orientation is furthermore strongly dependent on the electrolyte concentration and thus on the counterions in solution. In contrast, the effect of ions in the subphase on the dipolar alignment of water is zero. As a result, the capability of monolayer counter-charges to null the effect of dipolar orientation is strongly electrolyte-dependent. Notably, the different effects are additive for mixed charged/zwitterionic lipid systems occurring in nature. Specifically, for an E. coli lipid membrane extract consisting of both zwitterionic and negatively charged lipids, the water orientation can be explained by the sum of the constituents. Our results can be quantitatively reproduced using Gouy-Chapman theory, revealing the relatively straightforward electrostatic effects on the hydration of complex membrane interfaces.
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Affiliation(s)
- Clara-Magdalena Saak
- Faculty of Chemistry, Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, 1090, Vienna, Austria.
| | - Lisa B Dreier
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
- Graduate School of Materials Science in Mainz, Staudingerweg 9, 55128, Mainz, Germany
| | - Kevin Machel
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Ellen H G Backus
- Faculty of Chemistry, Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, 1090, Vienna, Austria.
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
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18
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Wang Y, Seki T, Gkoupidenis P, Chen Y, Nagata Y, Bonn M. Aqueous chemimemristor based on proton-permeable graphene membranes. Proc Natl Acad Sci U S A 2024; 121:e2314347121. [PMID: 38300862 PMCID: PMC10861866 DOI: 10.1073/pnas.2314347121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 11/30/2023] [Indexed: 02/03/2024] Open
Abstract
Memristive devices, electrical elements whose resistance depends on the history of applied electrical signals, are leading candidates for future data storage and neuromorphic computing. Memristive devices typically rely on solid-state technology, while aqueous memristive devices are crucial for biology-related applications such as next-generation brain-machine interfaces. Here, we report a simple graphene-based aqueous memristive device with long-term and tunable memory regulated by reversible voltage-induced interfacial acid-base equilibria enabled by selective proton permeation through the graphene. Surface-specific vibrational spectroscopy verifies that the memory of the graphene resistivity arises from the hysteretic proton permeation through the graphene, apparent from the reorganization of interfacial water at the graphene/water interface. The proton permeation alters the surface charge density on the CaF2 substrate of the graphene, affecting graphene's electron mobility, and giving rise to synapse-like resistivity dynamics. The results pave the way for developing experimentally straightforward and conceptually simple aqueous electrolyte-based neuromorphic iontronics using two-dimensional (2D) materials.
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Affiliation(s)
- Yongkang Wang
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing211189, China
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | - Takakazu Seki
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | - Paschalis Gkoupidenis
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | - Yunfei Chen
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing211189, China
| | - Yuki Nagata
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Mainz55128, Germany
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19
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Olivieri JF, Hynes JT, Laage D. Water dynamics and sum-frequency generation spectra at electrode/aqueous electrolyte interfaces. Faraday Discuss 2024; 249:289-302. [PMID: 37791579 DOI: 10.1039/d3fd00103b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The dynamics of water at interfaces between an electrode and an electrolyte is essential for the transport of redox species and for the kinetics of charge transfer reactions next to the electrode. However, while the effects of electrode potential and ion concentration on the electric double layer structure have been extensively studied, a comparable understanding of dynamical aspects is missing. Interfacial water dynamics presents challenges since it is expected to result from the complex combination of water-water, water-electrode and water-ion interactions. Here we perform molecular dynamics simulations of aqueous NaCl solutions at the interface with graphene electrodes, and examine the impact of both ion concentration and electrode potential on interfacial water reorientational dynamics. We show that for all salt concentrations water dynamics exhibits strongly asymmetric behavior: it slows down at increasingly positively charged electrodes but it accelerates at increasingly negatively charged electrodes. At negative potentials water dynamics is determined mostly by the electrode potential value, but in contrast at positive potentials it is governed both by ion-water and electrode-water interactions. We show how these strikingly different behaviors are determined by the interfacial hydrogen-bond network structure and by the ions' surface affinity. Finally, we indicate how the structural rearrangements impacting water dynamics can be probed via vibrational sum-frequency generation spectroscopy.
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Affiliation(s)
- Jean-François Olivieri
- PASTEUR, Department of Chemistry, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
| | - James T Hynes
- PASTEUR, Department of Chemistry, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Damien Laage
- PASTEUR, Department of Chemistry, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
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20
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Wang Y, Nagata Y, Bonn M. Substrate effect on charging of electrified graphene/water interfaces. Faraday Discuss 2024; 249:303-316. [PMID: 37772472 DOI: 10.1039/d3fd00107e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Graphene, a transparent two-dimensional (2D) conductive electrode, has brought extensive new perspectives and prospects to electrochemical systems, such as chemical sensors, energy storage, and energy conversion devices. In many of these applications, graphene, supported on a substrate, is in contact with an aqueous solution. An increasing number of studies indicate that the substrate, rather than graphene, determines the organization of water in contact with graphene, i.e., the electric double layer (EDL) structure near the electrified graphene, and the wetting behavior of the graphene: the graphene sheet is transparent in terms of its supporting substrate. By applying surface-specific heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy to the silicon dioxide (SiO2)-supported graphene electrode/aqueous electrolyte interface and comparing the data with those for the calcium fluoride (CaF2)-supported graphene [Y. Wang et al., Angew. Chem., Int. Ed., 2023, 62, e202216604], we discuss the impact of the different substrates on the charging of both the graphene and the substrate upon applying potentials. The SiO2-supported graphene shows pseudocapacitive behavior, consistent with the CaF2-supported graphene case, although the surface charges on SiO2 and CaF2 differ substantially. The SiO2 surface is already negatively charged at +0.57 V (vs. Pd/H2), and the negative surface charge is doubled when negative potentials are applied, in contrast with the CaF2 case, where the positive charge is reduced when negative potentials are applied. Interestingly, the charging of the graphene sheet is almost identical between the negatively charged SiO2 surface and positively charged CaF2 surface, demonstrating that the graphene charging is decoupled from the charging of the substrates.
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Affiliation(s)
- Yongkang Wang
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | - Yuki Nagata
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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21
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Qi D, Lukić MJ, Lu H, Gebauer D, Bonn M. Role of Water during the Early Stages of Iron Oxyhydroxide Formation by a Bacterial Iron Nucleator. J Phys Chem Lett 2024; 15:1048-1055. [PMID: 38253017 DOI: 10.1021/acs.jpclett.3c03327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Understanding the nucleation of iron oxides and the underlying hydrolysis of aqueous iron species is still challenging, and molecular-level insights into the orchestrated response of water, especially at the hydrolysis interface, are lacking. We follow iron(III) hydrolysis in the presence of a synthetic bacterial iron nucleator, which is a magnetosome membrane specific peptide, by using a constant pH titration technique. Three distinct hydrolysis regimes were identified. Interface-selective sum frequency generation (SFG) spectroscopy was used to probe the interfacial reaction and water in direct contact with the peptide. SFG data reveal that iron(III) species react quickly with interfacial peptides while continuously enhancing water alignment into the later stages of hydrolysis. The gradually aligning water molecules are associated with initially promoted (regimes I and II) and later suppressed (regime III) hydrolysis after the saturation of water alignment has occurred until regime II. These interfacial insights are crucial for understanding the early stage of iron oxide biomineralization.
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Affiliation(s)
- Daizong Qi
- Department of Materials and Textile Engineering, Nanotechnology Research Institute, Jiaxing University, Building No. 7, Jiaxing Intelligent Industry & Innovation Park, Jiaxing, Zhejiang 314001, P. R. China
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Miodrag J Lukić
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstrasse 9, 30167 Hannover, Germany
| | - Hao Lu
- Department of Materials and Textile Engineering, Nanotechnology Research Institute, Jiaxing University, Building No. 7, Jiaxing Intelligent Industry & Innovation Park, Jiaxing, Zhejiang 314001, P. R. China
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Denis Gebauer
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstrasse 9, 30167 Hannover, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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22
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Zhang Y, Zhang L, Cai C, Zhang J, Lu P, Shi N, Zhu W, He N, Pan X, Wang T, Feng Z. In situ study of structural changes: Exploring the mechanism of protein corona transition from soft to hard. J Colloid Interface Sci 2024; 654:935-944. [PMID: 37898077 DOI: 10.1016/j.jcis.2023.10.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 10/12/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023]
Abstract
HYPOTHESIS The process of protein corona changes has been widely believed to follow the Vroman effect, while protein structural change during the process is rarely reported, due to the lack of analytical methods. In-situ interpretation for protein structural change is critical to processes such as the recognition and transport of nanomaterials. EXPERIMENTS Molecular dynamics (MD) simulation was used to predict the deflection and twist of the protein tertiary structure. The structural changes of the surface protein corona during the interaction of nanoparticles (NPs) with lipid bilayer were probed in situ and real-time by sum frequency generation (SFG) spectroscopy. FINDINGS The ring tertiary structure of the protein corona is altered from vertical to horizontal on particle surface, a process of the soft-to-hard structural transition, which is contributed by the hydrogen bonding force between the protein and water molecules. The negatively charged protein corona can induce the redistribution of interfacial charge, leading to a more stable hydrogen bond network of the interfacial water. Our findings suggest that the structural change from flexible to rigid is a crucial process in the soft-to-hard transition of the protein corona, which will be a beneficial supplement to the Vroman effect of protein adsorption.
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Affiliation(s)
- Yixin Zhang
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Liqiang Zhang
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Chenglong Cai
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jixiang Zhang
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Pengyu Lu
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Neng Shi
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Weiran Zhu
- SceneRay Co., Ltd., Suzhou 215123, China
| | - Nongyue He
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xuchao Pan
- Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Ting Wang
- State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
| | - Zhangqi Feng
- Nanjing University of Science and Technology, Nanjing 210094, China
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23
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Chiang KY, Yu X, Yu CC, Seki T, Sun S, Bonn M, Nagata Y. Bulklike Vibrational Coupling of Surface Water Revealed by Sum-Frequency Generation Spectroscopy. PHYSICAL REVIEW LETTERS 2023; 131:256202. [PMID: 38181372 DOI: 10.1103/physrevlett.131.256202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 10/10/2023] [Accepted: 10/30/2023] [Indexed: 01/07/2024]
Abstract
Vibrational coupling between interfacial water molecules is important for energy dissipation after on-water chemistry, yet intensely debated. Here, we quantify the interfacial vibrational coupling strength through the linewidth of surface-specific vibrational spectra of the water's O─H (O─D) stretch region for neat H_{2}O/D_{2}O and their isotopic mixtures. The local-field-effect-corrected experimental SFG spectra reveal that the vibrational coupling between hydrogen-bonded interfacial water O─H groups is comparable to that in bulk water, despite the effective density reduction at the interface.
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Affiliation(s)
- Kuo-Yang Chiang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Shumei Sun
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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24
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Malik R, Chandra A, Das B, Chandra A. Theoretical Study of the Two-Dimensional Vibrational Sum Frequency Generation Spectroscopy of the Air-Water Interface at Varying Temperature and Its Connections to the Interfacial Structure and Dynamics. J Phys Chem B 2023; 127:10880-10895. [PMID: 38055625 DOI: 10.1021/acs.jpcb.3c03205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
We performed a theoretical study of the temperature variation of two-dimensional vibrational sum frequency generation (2D-VSFG) spectra of the OH stretch modes at air-water interfaces in the mid-IR region. The calculations are performed at four different temperatures from 250 to 325 K by using a combination of techniques involving response function formalism of nonlinear spectroscopy, electronic structure calculations, and molecular dynamics simulations. Also, the calculations are performed for isotopically dilute solutions so that the intra- and intermolecular coupling between the vibrational modes of interest can be ignored. We have established the connections of temperature variation of various frequency- and time-dependent features of the calculated spectra to the changes in the underlying structure and dynamics of the interfaces. The results reveal that interfacial water is dynamically more heterogeneous than bulk water, with three dominant dynamical processes exhibiting their corresponding time-dependent features in the 2D-VSFG spectrum. These are the spectral diffusion of hydrogen-bonded OH groups at the interface, conversion of an initially hydrogen-bonded OH group to a dangling OH which is a stable state for surface water, unlike the bulk water, and the third one, which involves the conversion of an initially free or dangling OH group to its hydrogen-bonded state at the interface. The temporal appearance of the cross peaks corresponding to interconversion of the hydrogen-bonded state to the dangling state or vice versa of an interfacial OH group is found to take place at a slower rate than the dynamics of spectral diffusion of hydrogen-bonded molecules at the interface, which, in turn, is slower than the corresponding spectral diffusion of bulk water molecules. The temperature variation of these dynamic processes can be linked to the decay of appropriate hydrogen-bond and non-hydrogen-bond time correlation functions of interfacial water molecules for the different air-water systems studied in this work.
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Affiliation(s)
- Ravi Malik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Abhilash Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Banshi Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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25
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Tan J, Wang M, Zhang J, Ye S. Determination of the Thickness of Interfacial Water by Time-Resolved Sum-Frequency Generation Vibrational Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18573-18580. [PMID: 38051545 DOI: 10.1021/acs.langmuir.3c02906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The physics and chemistry of a charged interface are governed by the structure of the electrical double layer (EDL). Determination of the interfacial water thickness (diw) of the charged interface is crucial to quantitatively describe the EDL structure, but it can be utilized with very scarce experimental methods. Here, we propose and verify that the vibrational relaxation time (T1) of the OH stretching mode at 3200 cm-1, obtained by time-resolved sum frequency generation vibrational spectroscopy with ssp polarizations, provides an effective tool to determine diw. By investigating the T1 values at the SiO2/NaCl solution interface, we established a time-space (T1-diw) relationship. We find that water has a T1 lifetime of ≥0.5 ps for diw ≤ 3 Å, while it displays bulk-like dynamics with T1 ≤ 0.2 ps for diw ≥ 9 Å. T1 decreases as diw increases from ∼3 Å to 9 Å. The hydration water at the DPPG lipid bilayer and LK15β protein interfaces has a thickness of ≥9 Å and shows a bulk-like feature. The time-space relationship will provide a novel tool to pattern the interfacial topography and heterogeneity in Ångstrom-depth resolution by imaging the T1 values.
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Affiliation(s)
- Junjun Tan
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Mengmeng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Jiahui Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Shuji Ye
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
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26
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Prasoon A, Yu X, Hambsch M, Bodesheim D, Liu K, Zacarias A, Nguyen NN, Seki T, Dianat A, Croy A, Cuniberti G, Fontaine P, Nagata Y, Mannsfeld SCB, Dong R, Bonn M, Feng X. Site-selective chemical reactions by on-water surface sequential assembly. Nat Commun 2023; 14:8313. [PMID: 38097633 PMCID: PMC10721922 DOI: 10.1038/s41467-023-44129-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/01/2023] [Indexed: 12/17/2023] Open
Abstract
Controlling site-selectivity and reactivity in chemical reactions continues to be a key challenge in modern synthetic chemistry. Here, we demonstrate the discovery of site-selective chemical reactions on the water surface via a sequential assembly approach. A negatively charged surfactant monolayer on the water surface guides the electrostatically driven, epitaxial, and aligned assembly of reagent amino-substituted porphyrin molecules, resulting in a well-defined J-aggregated structure. This constrained geometry of the porphyrin molecules prompts the subsequent directional alignment of the perylenetetracarboxylic dianhydride reagent, enabling the selective formation of a one-sided imide bond between porphyrin and reagent. Surface-specific in-situ spectroscopies reveal the underlying mechanism of the dynamic interface that promotes multilayer growth of the site-selective imide product. The site-selective reaction on the water surface is further demonstrated by three reversible and irreversible chemical reactions, such as imide-, imine-, and 1, 3-diazole (imidazole)- bonds involving porphyrin molecules. This unique sequential assembly approach enables site-selective chemical reactions that can bring on-water surface synthesis to the forefront of modern organic chemistry.
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Affiliation(s)
- Anupam Prasoon
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
- Max Planck Institute for Microstructure Physics, Halle (Saale), D-06120, Germany
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Mike Hambsch
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062, Dresden, Germany
| | - David Bodesheim
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062, Dresden, Germany
| | - Kejun Liu
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Angelica Zacarias
- Max Planck Institute for Microstructure Physics, Halle (Saale), D-06120, Germany
| | - Nguyen Ngan Nguyen
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Aerzoo Dianat
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062, Dresden, Germany
| | - Alexander Croy
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07737, Jena, Germany
| | - Gianaurelio Cuniberti
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062, Dresden, Germany
- Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, 01062, Dresden, Germany
| | - Philippe Fontaine
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190, Saint-Aubin, France
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Stefan C B Mannsfeld
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062, Dresden, Germany.
| | - Renhao Dong
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
- Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China.
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
| | - Xinliang Feng
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
- Max Planck Institute for Microstructure Physics, Halle (Saale), D-06120, Germany.
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27
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Parshotam S, Rehl B, Brown A, Gibbs JM. Relating the phase in vibrational sum frequency spectroscopy and second harmonic generation with the maximum entropy method. J Chem Phys 2023; 159:204707. [PMID: 38014784 DOI: 10.1063/5.0172667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/03/2023] [Indexed: 11/29/2023] Open
Abstract
Nonlinear optical methods, such as vibrational sum frequency generation (vSFG) and second harmonic generation (SHG), are powerful techniques to study elusive structures at charged buried interfaces. However, for the separation and determination of the Stern and diffuse layer spectra at these charged interfaces, complex vSFG spectra and, hence, the absolute phase need to be retrieved. The maximum entropy method is a useful tool for the retrieval of complex spectra from the intensity spectra; however, one caveat is that an understanding of the error phase is required. Here, for the first time, we provide a physically motivated understanding of the error phase. Determining the error phase from simulated spectra of oscillators with a spectral overlap, we show that for broadband vSFG spectra, such as for the silica/water interface, the diffuse and Stern layers' spectral overlap within the O-H stretching window results in a correlation between the error phase and the phase shift between the responses of these layers. This correlation makes the error phase sensitive to changes in Debye length from varying the ionic strength among other variations at the interface. Furthermore, the change in the magnitude of the error phase can be related to the absolute SHG phase, permitting the use of an error phase model that can utilize the SHG phase to predict the error phase and, hence, the complex vSFG spectra. Finally, we highlight limitations of this model for vSFG spectra with a poor overlap between the diffuse and Stern layer spectra (silica/HOD in D2O system).
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Affiliation(s)
- Shyam Parshotam
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Benjamin Rehl
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Alex Brown
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Julianne M Gibbs
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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28
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Buessler M, Maruyama S, Zelenka M, Onishi H, Backus EHG. Unravelling the interfacial water structure at the photocatalyst strontium titanate by sum frequency generation spectroscopy. Phys Chem Chem Phys 2023; 25:31471-31480. [PMID: 37962476 PMCID: PMC10664186 DOI: 10.1039/d3cp03829g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023]
Abstract
The direct conversion of solar energy to hydrogen is considered as a possible method to produce carbon neutral hydrogen fuel. The mechanism of photocatalytic water splitting involves the chemical breakdown of water and re-assembly into hydrogen and oxygen at the interface of a photocatalyst. The selection rules of a suitable material are well established, but the fundamental understanding of the mechanisms, occurring at the interface between the catalyst and the water, remains missing. Using surface specific sum frequency generation spectroscopy, we present here characterisation of the interface between water and the photocatalyst strontium titanate (SrTiO3). We monitor the OH-stretching vibrations present at the interface. Their variations of intensities and frequencies as functions of isotopic dilution, pH and salt concentration provide information about the nature of the hydrogen bonding environment. We observe the presence of water molecules that flip their orientation at pH 5 indicating the point of zero charge of the SrTiO3 layer. These water molecules are oriented with their hydrogen away from the surface when the pH of the solutions is below 5 and pointing towards the surface when the pH is higher than 5. Besides, water molecules donating a H-bond to probably surface TiOH groups are observed at all pH.
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Affiliation(s)
- Martin Buessler
- University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währinger Straße 42, 1090 Vienna, Austria.
- University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Straße 42, 1090 Vienna, Austria
| | - Shingo Maruyama
- Department of Applied Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan
| | - Moritz Zelenka
- University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währinger Straße 42, 1090 Vienna, Austria.
- University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Straße 42, 1090 Vienna, Austria
| | - Hiroshi Onishi
- Department of Chemistry, School of Science, Kobe University, Rokko-dai, Nada, Kobe, Japan
- Division of Advanced Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, Japan
| | - Ellen H G Backus
- University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währinger Straße 42, 1090 Vienna, Austria.
- University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Straße 42, 1090 Vienna, Austria
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29
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Sengupta S, Versluis J, Bakker HJ. Observation of a Two-Dimensional Hydrophobic Collapse at the Surface of Water Using Heterodyne-Detected Surface Sum-Frequency Generation. J Phys Chem Lett 2023; 14:9285-9290. [PMID: 37815274 PMCID: PMC10591499 DOI: 10.1021/acs.jpclett.3c01530] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 10/04/2023] [Indexed: 10/11/2023]
Abstract
We study the effect of sodium chloride (NaCl) on the properties of the interface of water and the surfactant dodecyl sulfate (DS-) using heterodyne-detected vibrational sum-frequency generation spectroscopy. We find that the signal of the O-H stretch vibrations of oriented water molecules at the interface is highly nonlinearly dependent on the NaCl concentration. This nonlinear dependence is explained by a combination of screening of the electric field of surface-bound DS- ions pointing into the bulk and screening of the Coulomb repulsion between the headgroups of the DS- ions in the surface plane. The latter effect strongly increases the oriented water signal within a limited NaCl concentration range of 10-100 mM, indicating a two-dimensional hydrophobic collapse of the surfactant layer. The occurrence of collapse is supported by model calculations of the surface potential and surface surfactant density.
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Affiliation(s)
| | - Jan Versluis
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Huib J. Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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30
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Chang H, Lozier EH, Ma E, Geiger FM. Quantification of Stern Layer Water Molecules, Total Potentials, and Energy Densities at Fused Silica:Water Interfaces for Adsorbed Alkali Chlorides, CTAB, PFOA, and PFAS. J Phys Chem A 2023; 127:8404-8414. [PMID: 37775181 DOI: 10.1021/acs.jpca.3c04434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
We have employed amplitude- and phase-resolved second-harmonic generation spectroscopy to investigate ion-specific effects of monovalent cations at the fused silica:water interface maintained under acidic, neutral, and alkaline conditions. We find a negligible dependence of the total potential (as negative as -400 mV at pH 14), the second-order nonlinear susceptibility (as large as 1.5 × 10-21 m2 V-1 at pH 14), the number of Stern layer water molecules (1 × 1015 cm-2 at pH 5.8), and the energy associated with water alignment upon going from neutral to high pH (ca. -24 kJ mol-1 to -48 kJ mol-1 at pH 13 and 14, close to the cohesive energy of liquid water but smaller than that of ice) on chlorides of the alkali series (M+ = Li+, Na+, K+, Rb+, and Cs+). Attempts are presented to provide estimates for the molecular hyperpolarizability of the cations and anions in the Stern layer at high pH, which arrive at ca. 20-fold larger values for αtotal ions(2) = αM+(2) + αOH-(2) + αCl-(2) when compared to water's molecular hyperpolarizability estimate from theory and point to a sizable contribution of deprotonated silanol groups at high pH. In contrast to the alkali series, a pronounced dependence of the total potential and the second-order nonlinear susceptibility on monovalent cationic (cetrimonium bromide, CTAB) and anionic (perfluorooctanoic and perfluorooctanesulfonic acid, PFOA and PFOS) surfactants was quantifiable. Our findings are consistent with a low surface coverage of the alkali cations and a high surface coverage of the surfactants. Moreover, they underscore the important contribution of Stern layer water molecules to the total potential and second-order nonlinear susceptibility. Finally, they demonstrate the applicability of heterodyne-detected second-harmonic generation spectroscopy for identifying perfluorinated acids at mineral:water interfaces.
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Affiliation(s)
- HanByul Chang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Emilie H Lozier
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Emily Ma
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Franz M Geiger
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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31
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Carr AJ, Lee SE, Uysal A. Ion and water adsorption to graphene and graphene oxide surfaces. NANOSCALE 2023; 15:14319-14337. [PMID: 37561081 DOI: 10.1039/d3nr02452k] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Graphene and graphene oxide (GO) are two particularly promising nanomaterials for a range of applications including energy storage, catalysis, and separations. Understanding the nanoscale interactions between ions and water near graphene and GO surfaces is critical for advancing our fundamental knowledge of these systems and downstream application success. This minireview highlights the necessity of using surface-specific experimental probes and computational techniques to fully characterize these interfaces, including the nanomaterial, surrounding water, and any adsorbed ions, if present. Key experimental and simulation studies considering water and ion structures near both graphene and GO are discussed. The major findings are: water forms 1-3 hydration layers near graphene; ions adsorb electrostatically to graphene under an applied potential; the chemical and physical properties of GO vary considerably depending on the synthesis route; and these variations influence water and ion adsorption to GO. Lastly, we offer outlooks and perspectives for these research areas.
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Affiliation(s)
- Amanda J Carr
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA.
| | - Seung Eun Lee
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA.
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA.
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32
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Nguyen TTP, Raji F, Nguyen CV, Nguyen NN, Nguyen AV. Effects of Charged Surfactants on Interfacial Water Structure and Macroscopic Properties of the Air-Water Interface. Chemphyschem 2023:e202300062. [PMID: 37679310 DOI: 10.1002/cphc.202300062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/09/2023]
Abstract
Surfactants are used to control the macroscopic properties of the air-water interface. However, the link between the surfactant molecular structure and the macroscopic properties remains unclear. Using sum-frequency generation spectroscopy and molecular dynamics simulations, two ionic surfactants (dodecyl trimethylammonium bromide, DTAB, and sodium dodecyl sulphate, SDS) with the same carbon chain lengths and charge magnitude (but different signs) of head groups interact and reorient interfacial water molecules differently. DTAB forms a thicker but sparser interfacial layer than SDS. It is due to the deep penetration into the adsorption zone of Br- counterions compared to smaller Na+ ones, and also due to the flip-flop orientation of water molecules. SDS alters two distinctive interfacial water layers into a layer where H+ points to the air, forming strong hydrogen bonding with the sulphate headgroup. In contrast, only weaker dipole-dipole interactions with the DTAB headgroup are formed as they reorient water molecules with H+ point down to the aqueous phase. Hence, with more molecules adsorbed at the interface, SDS builds up a higher interfacial pressure than DTAB, producing lower surface tension and higher foam stability at a similar bulk concentration. Our findings offer improved knowledge for understanding various processes in the industry and nature.
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Affiliation(s)
- Thao T P Nguyen
- School of Chemical Engineering and UQ Node of the ARC Centre of Excellence for Enabling Eco-efficient Beneficiation of Minerals, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Foad Raji
- School of Chemical Engineering and UQ Node of the ARC Centre of Excellence for Enabling Eco-efficient Beneficiation of Minerals, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cuong V Nguyen
- School of Chemical Engineering and UQ Node of the ARC Centre of Excellence for Enabling Eco-efficient Beneficiation of Minerals, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ngoc N Nguyen
- School of Chemical Engineering and UQ Node of the ARC Centre of Excellence for Enabling Eco-efficient Beneficiation of Minerals, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Anh V Nguyen
- School of Chemical Engineering and UQ Node of the ARC Centre of Excellence for Enabling Eco-efficient Beneficiation of Minerals, The University of Queensland, Brisbane, QLD 4072, Australia
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33
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Xu Y, Ma YB, Gu F, Yang SS, Tian CS. Structure evolution at the gate-tunable suspended graphene-water interface. Nature 2023; 621:506-510. [PMID: 37648858 DOI: 10.1038/s41586-023-06374-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 06/27/2023] [Indexed: 09/01/2023]
Abstract
Graphitic electrode is commonly used in electrochemical reactions owing to its excellent in-plane conductivity, structural robustness and cost efficiency1,2. It serves as prime electrocatalyst support as well as a layered intercalation matrix2,3, with wide applications in energy conversion and storage1,4. Being the two-dimensional building block of graphite, graphene shares similar chemical properties with graphite1,2, and its unique physical and chemical properties offer more varieties and tunability for developing state-of-the-art graphitic devices5-7. Hence it serves as an ideal platform to investigate the microscopic structure and reaction kinetics at the graphitic-electrode interfaces. Unfortunately, graphene is susceptible to various extrinsic factors, such as substrate effect8-10, causing much confusion and controversy7,8,10,11. Hereby we have obtained centimetre-sized substrate-free monolayer graphene suspended on aqueous electrolyte surface with gate tunability. Using sum-frequency spectroscopy, here we show the structural evolution versus the gate voltage at the graphene-water interface. The hydrogen-bond network of water in the Stern layer is barely changed within the water-electrolysis window but undergoes notable change when switching on the electrochemical reactions. The dangling O-H bond protruding at the graphene-water interface disappears at the onset of the hydrogen evolution reaction, signifying a marked structural change on the topmost layer owing to excess intermediate species next to the electrode. The large-size suspended pristine graphene offers a new platform to unravel the microscopic processes at the graphitic-electrode interfaces.
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Affiliation(s)
- Ying Xu
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai, China
| | - You-Bo Ma
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai, China
| | - Feng Gu
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai, China
| | - Shan-Shan Yang
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai, China
| | - Chuan-Shan Tian
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai, China.
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34
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A platform for exploring microscopic processes at electrode-electrolyte interfaces. Nature 2023:10.1038/d41586-023-02704-4. [PMID: 37648826 DOI: 10.1038/d41586-023-02704-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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35
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Kundu A, Yamaguchi S, Tahara T. Local pH at Nonionic and Zwitterionic Lipid/Water Interfaces Revealed by Heterodyne-Detected Electronic Sum-Frequency Generation: A Unified View to Predict Interfacial pH of Biomembranes. J Phys Chem B 2023; 127:5445-5452. [PMID: 37308160 PMCID: PMC10292198 DOI: 10.1021/acs.jpcb.3c02002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 05/20/2023] [Indexed: 06/14/2023]
Abstract
For biomembranes, which are composed of neutral as well as charged lipids, the local pH at lipid/water interfaces is extremely important in their structural formation and functional activity. In our previous study of the charged lipid/water interfaces, we found that the local pH at the interface is governed by the positive or negative sign of the charge of the lipid: i.e., the local pH is dictated by the repulsive or attractive electrostatic interaction between the charged lipid headgroup and the proton. Because of the lack of net charge in the headgroup of the neutral lipid, the factor determining the local pH at neutral lipid/water interfaces is less straightforward, and therefore it is more challenging to predict the local pH. Here we apply heterodyne-detected electronic sum frequency generation (HD-ESFG) spectroscopy to nonionic and zwitterionic lipids to investigate the local pH at the neutral lipid/water interfaces. The obtained results indicate that the local pH at the nonionic lipid/water interface is higher than in bulk water by 0.8 whereas the local pH at the zwitterionic lipid/water interface is lower by 0.6, although the latter is subject to significant uncertainty. The present HD-ESFG study on neutral lipids, combined with the previous study on charged lipids, presents a unified view to consider the local pH at biomembranes based on the balance between the electrostatic interaction and the hydrophobicity provided by the lipid.
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Affiliation(s)
- Achintya Kundu
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Shoichi Yamaguchi
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Department
of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Tahei Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center
for Advanced Photonics (RAP), Wako, Saitama 351-0198, Japan
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36
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Raji F, Nguyen CV, Nguyen NN, Nguyen TAH, Nguyen AV. Probing interfacial water structure induced by charge reversal and hydrophobicity of silica surface in the presence of divalent heavy metal ions using sum frequency generation spectroscopy. J Colloid Interface Sci 2023; 647:152-162. [PMID: 37247479 DOI: 10.1016/j.jcis.2023.05.125] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 05/12/2023] [Accepted: 05/17/2023] [Indexed: 05/31/2023]
Abstract
HYPOTHESIS Adsorption of divalent heavy metal ions (DHMIs) at the mineral-water interfaces changes interfacial chemical species and charges, interfacial water structure, Stern (SL), and diffuse (DL) layers. These molecular changes can be detected by probing changing orientation and hydrogen-bond network of interfacial water molecules in response to changing local charges and hydrophobicity. EXPERIMENTS Sum-frequency generation (SFG) spectroscopy was used to probe changes in vibrational resonances of interfacial OH vs. DHMI concentration and pH. SFG spectra were deconvoluted using the measured surface potential and maximum entropy method in conjunction with the electrical double-layer theory for the SL and DL structures and correlated by hydrophobicity. FINDINGS Three surface charge reversals (CRs) were detected at low (CR1), medium (CR2), and high (CR3) pHs. Unlike CR1, SFG signals were minimized at CR2 and CR3 for DHMIs-silica systems highlighting considerable alterations in the structure of interfacial waters due to the inner-sphere sorption of metal hydroxo complexes. SFG results showed "hydrophobic-like" stretching modes at > 3600 cm-1 for Pb-, Cu-, and Zn-treated silica. However, contact angle measurements revealed the hydrophobization of silica only in the presence of Pb(II), as confirmed by an in-depth SFG analysis of the hydrogen-bond network of the interfacial water molecules in the SL.
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Affiliation(s)
- Foad Raji
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Cuong V Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ngoc N Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tuan A H Nguyen
- Sustainable Minerals Institute, The University of Queensland, QLD 4072, Australia
| | - Anh V Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
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37
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Bañuelos JL, Borguet E, Brown GE, Cygan RT, DeYoreo JJ, Dove PM, Gaigeot MP, Geiger FM, Gibbs JM, Grassian VH, Ilgen AG, Jun YS, Kabengi N, Katz L, Kubicki JD, Lützenkirchen J, Putnis CV, Remsing RC, Rosso KM, Rother G, Sulpizi M, Villalobos M, Zhang H. Oxide- and Silicate-Water Interfaces and Their Roles in Technology and the Environment. Chem Rev 2023; 123:6413-6544. [PMID: 37186959 DOI: 10.1021/acs.chemrev.2c00130] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Interfacial reactions drive all elemental cycling on Earth and play pivotal roles in human activities such as agriculture, water purification, energy production and storage, environmental contaminant remediation, and nuclear waste repository management. The onset of the 21st century marked the beginning of a more detailed understanding of mineral aqueous interfaces enabled by advances in techniques that use tunable high-flux focused ultrafast laser and X-ray sources to provide near-atomic measurement resolution, as well as by nanofabrication approaches that enable transmission electron microscopy in a liquid cell. This leap into atomic- and nanometer-scale measurements has uncovered scale-dependent phenomena whose reaction thermodynamics, kinetics, and pathways deviate from previous observations made on larger systems. A second key advance is new experimental evidence for what scientists hypothesized but could not test previously, namely, interfacial chemical reactions are frequently driven by "anomalies" or "non-idealities" such as defects, nanoconfinement, and other nontypical chemical structures. Third, progress in computational chemistry has yielded new insights that allow a move beyond simple schematics, leading to a molecular model of these complex interfaces. In combination with surface-sensitive measurements, we have gained knowledge of the interfacial structure and dynamics, including the underlying solid surface and the immediately adjacent water and aqueous ions, enabling a better definition of what constitutes the oxide- and silicate-water interfaces. This critical review discusses how science progresses from understanding ideal solid-water interfaces to more realistic systems, focusing on accomplishments in the last 20 years and identifying challenges and future opportunities for the community to address. We anticipate that the next 20 years will focus on understanding and predicting dynamic transient and reactive structures over greater spatial and temporal ranges as well as systems of greater structural and chemical complexity. Closer collaborations of theoretical and experimental experts across disciplines will continue to be critical to achieving this great aspiration.
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Affiliation(s)
- José Leobardo Bañuelos
- Department of Physics, The University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Eric Borguet
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Gordon E Brown
- Department of Earth and Planetary Sciences, The Stanford Doerr School of Sustainability, Stanford University, Stanford, California 94305, United States
| | - Randall T Cygan
- Department of Soil and Crop Sciences, Texas A&M University, College Station, Texas 77843, United States
| | - James J DeYoreo
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Patricia M Dove
- Department of Geosciences, Department of Chemistry, Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Marie-Pierre Gaigeot
- Université Paris-Saclay, Univ Evry, CNRS, LAMBE UMR8587, 91025 Evry-Courcouronnes, France
| | - 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 2G2Canada
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - Anastasia G Ilgen
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Young-Shin Jun
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Nadine Kabengi
- Department of Geosciences, Georgia State University, Atlanta, Georgia 30303, United States
| | - Lynn Katz
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - James D Kubicki
- Department of Earth, Environmental & Resource Sciences, The University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Johannes Lützenkirchen
- Karlsruher Institut für Technologie (KIT), Institut für Nukleare Entsorgung─INE, Eggenstein-Leopoldshafen 76344, Germany
| | - Christine V Putnis
- Institute for Mineralogy, University of Münster, Münster D-48149, Germany
| | - Richard C Remsing
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Kevin M Rosso
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Gernot Rother
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Marialore Sulpizi
- Department of Physics, Ruhr Universität Bochum, NB6, 65, 44780, Bochum, Germany
| | - Mario Villalobos
- Departamento de Ciencias Ambientales y del Suelo, LANGEM, Instituto De Geología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Huichun Zhang
- Department of Civil and Environmental Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
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38
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Deng GH, Zhu Q, Rebstock J, Neves-Garcia T, Baker LR. Direct observation of bicarbonate and water reduction on gold: understanding the potential dependent proton source during hydrogen evolution. Chem Sci 2023; 14:4523-4531. [PMID: 37152268 PMCID: PMC10155912 DOI: 10.1039/d3sc00897e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 03/22/2023] [Indexed: 04/08/2023] Open
Abstract
The electrochemical conversion of CO2 represents a promising way to simultaneously reduce CO2 emissions and store chemical energy. However, the competition between CO2 reduction (CO2R) and the H2 evolution reaction (HER) hinders the efficient conversion of CO2 in aqueous solution. In water, CO2 is in dynamic equilibrium with H2CO3, HCO3 -, and CO3 2-. While CO2 and its associated carbonate species represent carbon sources for CO2R, recent studies by Koper and co-workers indicate that H2CO3 and HCO3 - also act as proton sources during HER (J. Am. Chem. Soc. 2020, 142, 4154-4161, ACS Catal. 2021, 11, 4936-4945, J. Catal. 2022, 405, 346-354), which can favorably compete with water at certain potentials. However, accurately distinguishing between competing reaction mechanisms as a function of potential requires direct observation of the non-equilibrium product distribution present at the electrode/electrolyte interface. In this study, we employ vibrational sum frequency generation (VSFG) spectroscopy to directly probe the interfacial species produced during competing HER/CO2R on Au electrodes. The vibrational spectra at the Ar-purged Na2SO4 solution/Au interface, where only HER occurs, show a strong peak around 3650 cm-1, which appears at the HER onset potential and is assigned to OH-. Notably, this species is absent for the CO2-purged Na2SO4 solution/gold interface; instead, a peak around 3400 cm-1 appears at catalytic potential, which is assigned to CO3 2- in the electrochemical double layer. These spectral reporters allow us to differentiate between HER mechanisms based on water reduction (OH- product) and HCO3 - reduction (CO3 2- product). Monitoring the relative intensities of these features as a function of potential in NaHCO3 electrolyte reveals that the proton donor switches from HCO3 - at low overpotential to H2O at higher overpotential. This work represents the first direct detection of OH- on a metal electrode produced during HER and provides important insights into the surface reactions that mediate selectivity between HER and CO2R in aqueous solution.
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Affiliation(s)
- Gang-Hua Deng
- State Key Laboratory of Information Photonic and Optical Communications and School of Science, Beijing University of Posts and Telecommunications (BUPT) Beijing 100876 P. R. China
| | - Quansong Zhu
- Department of Chemistry and Biochemistry, The Ohio State University Columbus Ohio 43210 USA
| | - Jaclyn Rebstock
- Department of Chemistry and Biochemistry, The Ohio State University Columbus Ohio 43210 USA
| | - Tomaz Neves-Garcia
- Department of Chemistry and Biochemistry, The Ohio State University Columbus Ohio 43210 USA
| | - L Robert Baker
- Department of Chemistry and Biochemistry, The Ohio State University Columbus Ohio 43210 USA
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39
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Wei F, Urashima SH, Nihonyanagi S, Tahara T. Elucidation of the pH-Dependent Electric Double Layer Structure at the Silica/Water Interface Using Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy. J Am Chem Soc 2023; 145:8833-8846. [PMID: 37068781 PMCID: PMC10143621 DOI: 10.1021/jacs.2c11344] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Indexed: 04/19/2023]
Abstract
The silica/water interface is one of the most abundant charged interfaces in natural environments, and the elucidation of the water structure at the silica/water interface is essential. In the present study, we measured the interface-selective vibrational (χ(2)) spectra in the OH stretch region of the silica/water interface in a wide pH range of pH 2.0-12.0 while changing the salt concentration by heterodyne-detected vibrational sum-frequency generation spectroscopy. With the help of singular value decomposition analysis, it is shown that the imaginary part of the χ(2) (Imχ(2)) spectra can be decomposed into the spectra of the diffuse Gouy-Chapman layer (DL) and the compact Stern layer (SL), which enables us to quantitatively analyze the spectra of DL and SL separately. The salt-concentration dependence of the DL spectra at different pH values is analyzed using the modified Gouy-Chapman theory, and the pH-dependent surface charge density and the pKa value (4.8 ± 0.2) of the silica/water interface are evaluated. Furthermore, it is found that the pH-dependent change of the SL spectra is quantitatively explained by three spectral components that represent the three characteristic water species appearing in different pH regions in SL. The quantitative understanding obtained from the analysis of each spectral component in the Imχ(2) spectra provides a clear molecular-level picture of the electric double layer at the silica/water interface.
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Affiliation(s)
- Feng Wei
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Shu-hei Urashima
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Satoshi Nihonyanagi
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center
for Advanced Photonics (RAP), Wako, Saitama 351-0198, Japan
| | - Tahei Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center
for Advanced Photonics (RAP), Wako, Saitama 351-0198, Japan
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40
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Nayak S, Kumal RR, Lee SE, Uysal A. Elucidating Trivalent Ion Adsorption at Floating Carboxylic Acid Monolayers: Charge Reversal or Water Reorganization? J Phys Chem Lett 2023; 14:3685-3690. [PMID: 37036360 DOI: 10.1021/acs.jpclett.3c00225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
We study the adsorption of trivalent neodymium on floating arachidic acid films at the air-water interface by two complementary surface specific probes, sum frequency generation spectroscopy and X-ray fluorescence near total reflection. In the absence of background ions, neodymium ions compensate for the surface charge of the arachidic acid film at a bulk concentration of 50 μM without any charge reversal. Increasing the bulk concentration to 1 mM does not change the neodymium surface coverage but affects the interfacial water structure significantly. In the presence of a high concentration of NaCl, there is overcharging at 1 mM Nd3+, i.e., 30% more Nd3+ than needed to compensate for the surface charge. These results show that the total coverage of neodymium ions is not enough to describe the complete picture at the interface, and interfacial water and ion coverage needs to be considered together to understand more complex ion adsorption and transport processes.
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Affiliation(s)
- Srikanth Nayak
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Raju R Kumal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Seung Eun Lee
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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41
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Hsiao Y, Chou TH, Patra A, Wen YC. Momentum-dependent sum-frequency vibrational spectroscopy of bonded interface layer at charged water interfaces. SCIENCE ADVANCES 2023; 9:eadg2823. [PMID: 37043576 PMCID: PMC10096568 DOI: 10.1126/sciadv.adg2823] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/14/2023] [Indexed: 06/19/2023]
Abstract
Interface-specific hydrogen (H)-bonding network of water directly controls the energy transfer and chemical reaction pathway at many charged aqueous interfaces, yet to characterize these bonded water layer structures remains a challenge. We now develop a sum-frequency spectroscopic scheme with varying photon momenta as an all-optic solution for retrieving the vibrational spectra of the bonded water layer and the ion diffuse layer and, hence, microscopic structural and charging information about an interface. Application of the method to a model surfactant-water interface reveals a hidden weakly donor H-bonded water species, suggesting an asymmetric hydration-shell structure of fully solvated surfactant headgroups. In another application to a zwitterionic phosphatidylcholine lipid monolayer-water interface, we find a highly polarized bonded water layer structure associating to the phosphatidylcholine headgroup, while the diffuse layer contribution is experimentally proven to be negligible. Our all-optic method offers an in situ microscopic probe of electrochemical and biological interfaces and the route toward future imaging and ultrafast dynamics studies.
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42
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Korotkevich AA, Moll CJ, Versluis J, Bakker HJ. Molecular Orientation of Carboxylate Anions at the Water-Air Interface Studied with Heterodyne-Detected Vibrational Sum-Frequency Generation. J Phys Chem B 2023; 127:4544-4553. [PMID: 36917504 DOI: 10.1021/acs.jpcb.2c08992] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The carboxylate anion group plays an important role in many (bio)chemical systems and polymeric materials. In this work, we study the orientation of carboxylate anions with various aliphatic and aromatic substituents at the water-air interface by probing the carboxylate stretch vibrations with heterodyne-detected vibrational sum-frequency generation spectroscopy in different polarization configurations. We find that carboxylate groups with small aliphatic substituents show a large tilt angle with respect to the surface normal and that this angle decreases with increasing size of the substituent. We further use the information about the orientation of the carboxylate group to determine the hyperpolarizability components of this group.
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Affiliation(s)
| | - Carolyn J Moll
- Ultrafast Spectroscopy, AMOLF, Science Park 104, Amsterdam 1098XG, Netherlands
| | - Jan Versluis
- Ultrafast Spectroscopy, AMOLF, Science Park 104, Amsterdam 1098XG, Netherlands
| | - Huib J Bakker
- Ultrafast Spectroscopy, AMOLF, Science Park 104, Amsterdam 1098XG, Netherlands
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43
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Shin S, Willard AP. Quantifying the Molecular Polarization Response of Liquid Water Interfaces at Heterogeneously Charged Surfaces. J Chem Theory Comput 2023; 19:1843-1852. [PMID: 36866865 DOI: 10.1021/acs.jctc.2c01256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
The hydration shells of proteins mediate interactions, such as small molecule binding, that are vital to their biological function or in some cases their dysfunction. However, even when the structure of a protein is known, the properties of its hydration environment cannot be easily predicted due to the complex interplay between protein surface heterogeneity and the collective structure of water's hydrogen bonding network. This manuscript presents a theoretical study of the influence of surface charge heterogeneity on the polarization response of the liquid water interface. We focus our attention on classical point charge models of water, where the polarization response is limited to molecular reorientation. We introduce a new computational method for analyzing simulation data that is capable of quantifying water's collective polarization response and determining the effective surface charge distribution of hydrated surfaces over atomistic length scales. To illustrate the utility of this method, we present the results of molecular dynamics simulations of liquid water in contact with a heterogeneous model surface and the CheY protein.
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Affiliation(s)
- Sucheol Shin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Adam P Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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44
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Wang Y, Seki T, Liu X, Yu X, Yu CC, Domke KF, Hunger J, Koper MTM, Chen Y, Nagata Y, Bonn M. Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode. Angew Chem Int Ed Engl 2023; 62:e202216604. [PMID: 36592114 DOI: 10.1002/anie.202216604] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/21/2022] [Accepted: 01/02/2023] [Indexed: 01/03/2023]
Abstract
Molecular-level insight into interfacial water at a buried electrode interface is essential in electrochemistry, but spectroscopic probing of the interface remains challenging. Here, using surface-specific heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy, we directly access the interfacial water in contact with the graphene electrode supported on calcium fluoride (CaF2 ). We find phase transition-like variations of the HD-SFG spectra vs. applied potentials, which arises not from the charging/discharging of graphene but from the charging/discharging of the CaF2 substrate through the pseudocapacitive process. The potential-dependent spectra are nearly identical to the pH-dependent spectra, evidencing that the pseudocapacitive behavior is associated with a substantial local pH change induced by water dissociation between the CaF2 and graphene. Our work evidences the local molecular-level effects of pseudocapacitive charging at an electrode/aqueous electrolyte interface.
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Affiliation(s)
- Yongkang Wang
- School of Mechanical Engineering, Southeast University, 211189, Nanjing, China.,Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Xuan Liu
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden (The, Netherlands
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Katrin F Domke
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.,University Duisburg-Essen, Faculty of Chemistry, Universitätsstraße 5, 45141, Essen, Germany
| | - Johannes Hunger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Marc T M Koper
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden (The, Netherlands
| | - Yunfei Chen
- School of Mechanical Engineering, Southeast University, 211189, Nanjing, China
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
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45
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Wang Y, Seki T, Yu X, Yu CC, Chiang KY, Domke KF, Hunger J, Chen Y, Nagata Y, Bonn M. Chemistry governs water organization at a graphene electrode. Nature 2023; 615:E1-E2. [PMID: 36859590 DOI: 10.1038/s41586-022-05669-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 12/19/2022] [Indexed: 03/03/2023]
Affiliation(s)
- Yongkang Wang
- School of Mechanical Engineering, Southeast University, Nanjing, China
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Mainz, Germany
| | | | - Katrin F Domke
- Max Planck Institute for Polymer Research, Mainz, Germany
- Faculty of Chemistry, University Duisburg-Essen, Essen, Germany
| | | | - Yunfei Chen
- School of Mechanical Engineering, Southeast University, Nanjing, China.
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Mainz, Germany.
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz, Germany.
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46
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Chen W, Sanders SE, Özdamar B, Louaas D, Brigiano FS, Pezzotti S, Petersen PB, Gaigeot MP. On the Trail of Molecular Hydrophilicity and Hydrophobicity at Aqueous Interfaces. J Phys Chem Lett 2023; 14:1301-1309. [PMID: 36724059 DOI: 10.1021/acs.jpclett.2c03300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Uncovering microscopic hydrophilicity and hydrophobicity at heterogeneous aqueous interfaces is essential as it dictates physico/chemical properties such as wetting, the electrical double layer, and reactivity. Several molecular and spectroscopic descriptors were proposed, but a major limitation is the lack of connections between them. Here, we combine density functional theory-based MD simulations (DFT-MD) and SFG spectroscopy to explore how interfacial water responds in contact with self-assembled monolayers (SAM) of tunable hydrophilicity. We introduce a microscopic metric to track the transition from hydrophobic to hydrophilic interfaces. This metric combines the H/V descriptor, a structural descriptor based on the preferential orientation within the water network in the topmost binding interfacial layer (BIL) and spectroscopic fingerprints of H-bonded and dangling OH groups of water carried by BIL-resolved SFG spectra. This metric builds a bridge between molecular descriptors of hydrophilicity/hydrophobicity and spectroscopically measured quantities and provides a recipe to quantitatively or qualitatively interpret experimental SFG signals.
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Affiliation(s)
- Wanlin Chen
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
| | - Stephanie E Sanders
- Department of Chemistry and Biochemistry, Ruhr University Bochum, 44801Bochum, Germany
| | - Burak Özdamar
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
| | - Dorian Louaas
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
| | - Flavio Siro Brigiano
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
- Laboratoire de Chimie Théorique, Sorbonne Université, UMR 7616 CNRS, 4 Place Jussieu, 75005Paris, France
| | - Simone Pezzotti
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
- Department of Physical Chemistry II, Ruhr University Bochum, D-44801Bochum, Germany
| | - Poul B Petersen
- Department of Chemistry and Biochemistry, Ruhr University Bochum, 44801Bochum, Germany
| | - Marie-Pierre Gaigeot
- Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France
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47
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Bandyopadhyay D, Bhanja K, Choudhury N. On the Propensity of Excess Hydroxide Ions at the Alcohol Monolayer-Water Interface. J Phys Chem B 2023; 127:783-793. [PMID: 36639623 DOI: 10.1021/acs.jpcb.2c05719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Atomistic molecular dynamics simulations have been employed to study the self-ion (H+ and OH-) distribution at the interface between long-chain C16-OH alcohol (cetyl alcohol) monolayer and water. It is well known that the free air-water interface is acidic due to accumulation of the hydronium (H3O+) ions at the interface. In the present study, we have observed that contrary to the air-water interface, at the long-chain alcohol monolayer-water interface, it is the hydroxide (OH-) ion, not the hydronium ion (H3O+) that gets accumulated. By calculating the potential of mean forces, it is confirmed that there is extra stabilization for the OH- ions at the interface relative to the bulk, but no such stabilization is observed for the H3O+ ions. By analyzing the interaction of the self-ions with other constituents in the medium, it is clearly shown that the favorable interaction of the OH- ions with the alcoholic -OH groups stabilizes this ion at the interface. By calculating coordination numbers of the self-ions it is observed that around 50% water neighbors are substituted by alcoholic -OH in case of the hydroxide ion at the interface, whereas in the case of hydronium ions, only 15% water neighbors are substituted by the alcoholic -OH. The most interesting observation about the local structure and H-bonding pattern is that the hydroxide ion acts solely as the H-bond acceptor, but the hydronium ion acts only as the H-bond donor.
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Affiliation(s)
| | - Kalyan Bhanja
- Heavy Water Division, Bhabha Atomic Research Centre, Mumbai400 085, India
| | - Niharendu Choudhury
- Theoretical Chemistry Section, Chemistry Division, Bhabha Atomic Research Centre, Mumbai400 085, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai400 094, India
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48
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Rashwan M, Rehl B, Romaniuk N, Gibbs JM. Probing Silica-Kaolinite Interactions with Sum Frequency Generation Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:15984-15994. [PMID: 36519947 DOI: 10.1021/acs.langmuir.2c02414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Treating the oil sands tailings ponds is a major challenge because of the vast amounts of tailings and the need for a reliable treatment technique for releasing water and generating the highly consolidated material required for land reclamation. Treatment with chemicals such as lime (calcium (hydr)oxide) is a promising technology for tailings dewatering and consolidation, particularly at higher pH. Given that kaolinite and silica minerals are the main constituents of many oil sands, we have investigated the influence of lime and NaOH addition on the silica/aqueous kaolinite interface over the pH range 7.4-12.4 using vibrational sum frequency generation spectroscopy (SFG). With lime addition, at pH 12.0 and above we observe a complete disappearance of the vibrational features of the interfacial water molecules for planar silica in contact with an aqueous dispersion of kaolinite particles. A concurrent increase in the amount of adsorbed kaolinite on the silica surface at pH 12.0 and above is observed, shown in the increased intensity of the kaolinite SFG peak at 3694 cm-1. This suggests that the absence of water features in the SFG spectra is associated with conditions that facilitate dewatering. With NaOH addition, however, the interfacial water SF intensity is still significant even under highly alkaline conditions despite the increase in adsorbed kaolinite at high pH. To better understand the SFG observations and get a deeper insight into the chemistry of the silica/aqueous kaolinite interface, we measure the ζ-potential on the planar silica/aqueous interface and kaolinite aqueous dispersions under the same pH conditions with NaOH and lime addition.
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Affiliation(s)
- Mokhtar Rashwan
- Department of Chemistry, University of Alberta, Edmonton, AlbertaT6G 2G2, Canada
| | - Benjamin Rehl
- Department of Chemistry, University of Alberta, Edmonton, AlbertaT6G 2G2, Canada
| | - Nikolas Romaniuk
- Graymont Inc. 200-10991, Shelbridge Way, Richmond, British ColumbiaV6X 3C6, Canada
| | - Julianne M Gibbs
- Department of Chemistry, University of Alberta, Edmonton, AlbertaT6G 2G2, Canada
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49
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Ober P, Hunger J, Kolbinger SH, Backus EHG, Bonn M. Ion Adsorption and Desorption at the CaF 2 -Water Interface Probed by Flow Experiments and Vibrational Spectroscopy. Angew Chem Int Ed Engl 2022; 61:e202207017. [PMID: 36006393 PMCID: PMC9828343 DOI: 10.1002/anie.202207017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Indexed: 01/12/2023]
Abstract
The dissolution of minerals in contact with water plays a crucial role in geochemistry. However, obtaining molecular insight into interfacial chemistry is challenging. Dissolution typically involves the release of ions from the surface, giving rise to a charged mineral surface. This charge affects the interfacial water arrangement, which can be investigated by surface-specific vibrational Sum Frequency Generation (v-SFG) spectroscopy. For the fluorite-water interface, recent spectroscopic studies concluded that fluoride adsorption/desorption determines the surface charge, which contrasts zeta potential measurements assigning this role to the calcium ion. By combining v-SFG spectroscopy and flow experiments with systematically suppressed dissolution, we uncover the interplay of dominant fluoride and weak calcium adsorption/desorption, resolving the controversy in the literature. We infer the calcium contribution to be orders of magnitude smaller, emphasizing the sensitivity of our approach.
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Affiliation(s)
- Patrick Ober
- Department of Molecular SpectroscopyMax Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
| | - Johannes Hunger
- Department of Molecular SpectroscopyMax Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
| | - Sophia H. Kolbinger
- Department of Molecular SpectroscopyMax Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
| | - Ellen H. G. Backus
- Department of Molecular SpectroscopyMax Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany,University of ViennaFaculty of ChemistryInstitute of Physical ChemistryWaehringer Strasse 421090ViennaAustria
| | - Mischa Bonn
- Department of Molecular SpectroscopyMax Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
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50
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Hunger J, Schaefer J, Ober P, Seki T, Wang Y, Prädel L, Nagata Y, Bonn M, Bonthuis DJ, Backus EHG. Nature of Cations Critically Affects Water at the Negatively Charged Silica Interface. J Am Chem Soc 2022; 144:19726-19738. [PMID: 36273333 PMCID: PMC9634801 DOI: 10.1021/jacs.2c02777] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Indexed: 11/30/2022]
Abstract
Understanding the collective behavior of ions at charged surfaces is of paramount importance for geological and electrochemical processes. Ions screen the surface charge, and interfacial fields break the centro-symmetry near the surface, which can be probed using second-order nonlinear spectroscopies. The effect of electrolyte concentration on the nonlinear optical response has been semi-quantitatively explained by mean-field models based on the Poisson-Boltzmann equation. Yet, to explain previously reported ion-specific effects on the spectroscopic response, drastic ion-specific changes in the interfacial properties, including surface acidities and dielectric permittivities, or strong ion adsorption/desorption had to be invoked. Here, we use sum-frequency generation (SFG) spectroscopy to probe the symmetry-breaking of water molecules at a charged silica surface in contact with alkaline metal chloride solutions (LiCl, NaCl, KCl, and CsCl) at various concentrations. We find that the water response varies with the cation: the SFG response is markedly enhanced for LiCl compared to CsCl. We show that within mean-field models, neither specific ion-surface interactions nor a reduced dielectric constant of water near the interface can account for the variation of spectral intensities with cation nature. Molecular dynamics simulations confirm that the decay of the electrochemical potential only weakly depends on the salt type. Instead, the effect of different salts on the optical response is indirect, through the reorganization of the interfacial water: the salt-type-dependent alignment of water directly at the interface can explain the observations.
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Affiliation(s)
- Johannes Hunger
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Jan Schaefer
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Patrick Ober
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Takakazu Seki
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Yongkang Wang
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Leon Prädel
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Yuki Nagata
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Mischa Bonn
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Douwe Jan Bonthuis
- Institute
of Theoretical and Computational Physics, Graz University of Technology, Petersgasse16/II, 8010Graz, Austria
| | - Ellen H. G. Backus
- Department
for Molecular Spectroscopy, Max Planck Institute
for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
- Faculty
of Chemistry, Institute of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090Vienna, Austria
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