1
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Qi Z, Zhuang J, Yang W, Yang Y, Wang L, Cai C, Zhang Z, Hua Y, Abdirazik D, Li L, Shi W, Hao J. Symmetrical-waveform alternating current-promoted NiO xH y electrocatalysis for the oxygen evolution reaction. Chem Commun (Camb) 2023; 59:10632-10635. [PMID: 37580959 DOI: 10.1039/d3cc02704j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
Here we describe a symmetrical waveform alternating current strategy that provides a solution for obtaining gradient oxygen vacancies (VO) in situ. The unique gradient VO provides multiple stairs to reduce the reaction kinetics and thus contributes to a total increase of up to 84.7% in current density.
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Affiliation(s)
- Zhihao Qi
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Jinwei Zhuang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Wantong Yang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Yonggang Yang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Ling Wang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Chenyang Cai
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Zhilin Zhang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Yutao Hua
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Dilnur Abdirazik
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Longhua Li
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Weidong Shi
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
| | - Jinhui Hao
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, China.
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2
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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: 0] [Impact Index Per Article: 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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3
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Reynolds JG, Graham TR, Pearce CI. Ion hydration controls self-diffusion in multicomponent aqueous electrolyte solutions of NaNO2-NaOH-H2O. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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4
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Cota R, Woutersen S, Bakker HJ. Accelerated Vibrational Energy Relaxation of Water in Alkaline Environments. J Phys Chem B 2021; 125:11980-11986. [PMID: 34672577 PMCID: PMC8573739 DOI: 10.1021/acs.jpcb.1c02730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
We
observe that hydrated hydroxide ions introduce an additional
relaxation channel for the vibrational relaxation of the OD vibrations
of HDO molecules in aqueous NaOH solutions. This additional relaxation
path involves resonant (Förster) vibrational energy transfer
from the excited OD vibration to OH stretch vibrations of hydrated
OH– complexes. This energy transfer constitutes
an efficient mechanism for dissipation of the OD vibrational energy,
as the accepting OH stretch vibrations show an extremely rapid subsequent
relaxation with a time constant of <200 fs. We find that the Förster
energy transfer is characterized by a Förster radius of 2.8
± 0.2 Å.
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Affiliation(s)
- Roberto Cota
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands.,AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
| | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - Huib J Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
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5
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Hanson MD, Readnour JA, Hassanali AA, Corcelli SA. Coupled Local-Mode Approach for the Calculation of Vibrational Spectra: Application to Protonated Water Clusters. J Phys Chem Lett 2021; 12:9226-9232. [PMID: 34529914 DOI: 10.1021/acs.jpclett.1c02254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spectroscopic studies of protonated water clusters (PWCs) have yielded enormous insights into the fundamental nature of the hydrated proton. Here, we introduce a new coupled local-mode (CLM) approach to calculate PWC OH stretch vibrational spectra. The CLM method combines a sampling of representative configurations from density functional theory (DFT)-based ab initio molecular dynamics (AIMD) simulations with DFT calculations of local-mode vibrational frequencies and couplings. Calculations of inhomogeneous OH stretch vibrational spectra for H+(H2O)4 and H+(H2O)21 agree well with experiment and higher-level calculations, and decompositions of the calculated spectra in terms of the coupled modes aids in the interpretation of the spectra. This observation is consistent with the idea that capturing anharmonicity and coupling is as important to accuracy as the underlying level of electronic structure theory. The CLM calculations can easily discern the configuration that dominates the experimental measurement for H+(H2O)5, which can adopt several low-energy conformations.
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Affiliation(s)
- Matthew D Hanson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Janel A Readnour
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Ali A Hassanali
- Condensed Matter and Statistical Physics, International Centre for Theoretical Physics, Strada Costiera, 11 I - 34151 Trieste, Italy
| | - Steven A Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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6
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Drexler CI, Cracchiolo OM, Myers RL, Okur HI, Serrano AL, Corcelli SA, Cremer PS. Local Electric Fields in Aqueous Electrolytes. J Phys Chem B 2021; 125:8484-8493. [PMID: 34313130 DOI: 10.1021/acs.jpcb.1c03257] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrational Stark shifts were explored in aqueous solutions of organic molecules with carbonyl- and nitrile-containing constituents. In many cases, the vibrational resonances from these moieties shifted toward lower frequency as salt was introduced into solution. This is in contrast to the blue-shift that would be expected based upon Onsager's reaction field theory. Salts containing well-hydrated cations like Mg2+ or Li+ led to the most pronounced Stark shift for the carbonyl group, while poorly hydrated cations like Cs+ had the greatest impact on nitriles. Moreover, salts containing I- gave rise to larger Stark shifts than those containing Cl-. Molecular dynamics simulations indicated that cations and anions both accumulate around the probe in an ion- and probe-dependent manner. An electric field was generated by the ion pair, which pointed from the cation to the anion through the vibrational chromophore. This resulted from solvent-shared binding of the ions to the probes, consistent with their positions in the Hofmeister series. The "anti-Onsager" Stark shifts occur in both vibrational spectroscopy and fluorescence measurements.
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Affiliation(s)
| | - Olivia M Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | | | - Halil I Okur
- Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Arnaldo L Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Steven A Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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7
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de Oliveira DM, Bredt AJ, Miller TC, Corcelli SA, Ben-Amotz D. Spectroscopic and Structural Characterization of Water-Shared Ion-Pairs in Aqueous Sodium and Lithium Hydroxide. J Phys Chem B 2021; 125:1439-1446. [PMID: 33512171 DOI: 10.1021/acs.jpcb.0c10564] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Aria J. Bredt
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tierney C. Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Steven A. Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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8
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Wang Y, Song D, Zhou Y, Cheng C, Zhang Y, Pearce CI, Wang Z, Clark SB, Zhu J, Rosso KM, Zhu Z, Zhang X. Molecular Examination of Ion-Pair Competition in Alkaline Aluminate Solutions Using In Situ Liquid SIMS. Anal Chem 2020; 93:1068-1075. [DOI: 10.1021/acs.analchem.0c04070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Yining Wang
- Nanjing University of Science and Technology, 200 Xiaolingwei Street, Xuanwu
District, Nanjing 210094, China
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Duo Song
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Yadong Zhou
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Cuixia Cheng
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Yanyan Zhang
- Institute of Chemistry, Chinese Academy of Sciences, No. 2, North First Street, Zhongguancun, Haidian District, Beijing 100190, China
| | - Carolyn I. Pearce
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Zheming Wang
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Sue B. Clark
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Junwu Zhu
- Nanjing University of Science and Technology, 200 Xiaolingwei Street, Xuanwu
District, Nanjing 210094, China
| | - Kevin M. Rosso
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Zihua Zhu
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
| | - Xin Zhang
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, United States
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9
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Key activity descriptors of nickel-iron oxygen evolution electrocatalysts in the presence of alkali metal cations. Nat Commun 2020; 11:6181. [PMID: 33268768 PMCID: PMC7710789 DOI: 10.1038/s41467-020-19729-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 10/26/2020] [Indexed: 11/08/2022] Open
Abstract
Efficient oxygen evolution reaction (OER) electrocatalysts are pivotal for sustainable fuel production, where the Ni-Fe oxyhydroxide (OOH) is among the most active catalysts for alkaline OER. Electrolyte alkali metal cations have been shown to modify the activity and reaction intermediates, however, the exact mechanism is at question due to unexplained deviations from the cation size trend. Our X-ray absorption spectroelectrochemical results show that bigger cations shift the Ni2+/(3+δ)+ redox peak and OER activity to lower potentials (however, with typical discrepancies), following the order CsOH > NaOH ≈ KOH > RbOH > LiOH. Here, we find that the OER activity follows the variations in electrolyte pH rather than a specific cation, which accounts for differences both in basicity of the alkali hydroxides and other contributing anomalies. Our density functional theory-derived reactivity descriptors confirm that cations impose negligible effect on the Lewis acidity of Ni, Fe, and O lattice sites, thus strengthening the conclusions of an indirect pH effect. It is commonly accepted that electrolyte alkali metal cations modify the catalytic activity for oxygen evolution reaction. Here the authors challenge this assumption, showing that the activity is actually affected by a change in the electrolyte pH rather than a specific alkali cation.
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10
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Zeng Y, Li A, Yan T. Hydrogen Bond Dynamics in the Solvation Shell on Proton Transfer in Aqueous Solution. J Phys Chem B 2020; 124:1817-1823. [DOI: 10.1021/acs.jpcb.0c00990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Yonghui Zeng
- Institute of New Energy Material Chemistry, School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University, Tianjin 300350, China
| | - Ailin Li
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Tianying Yan
- Institute of New Energy Material Chemistry, School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University, Tianjin 300350, China
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11
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Graham TR, Hu JZ, Zhang X, Dembowski M, Jaegers NR, Wan C, Bowden M, Lipton AS, Felmy AR, Clark SB, Rosso KM, Pearce CI. Unraveling Gibbsite Transformation Pathways into LiAl-LDH in Concentrated Lithium Hydroxide. Inorg Chem 2019; 58:12385-12394. [DOI: 10.1021/acs.inorgchem.9b02000] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Trent R. Graham
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- The Voiland School of Chemical and Biological Engineering, Washington State University, Pullman, Washington 99164, United States
| | - Jian Zhi Hu
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Biological Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Xin Zhang
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Mateusz Dembowski
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Nicholas R. Jaegers
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Biological Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Chuan Wan
- Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Mark Bowden
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Andrew S. Lipton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Andrew R. Felmy
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Sue B. Clark
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
- Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Kevin M. Rosso
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Carolyn I. Pearce
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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12
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Liu YY, Zhang SZ, Ying YL, Xia HL, Hua X, Long YT. Ion-Specific Effects on Hydrogen Bond Network at a Submicropore Confined Liquid-Vacuum Interface: An in Situ Liquid ToF-SIMS Study. J Phys Chem Lett 2019; 10:4935-4941. [PMID: 31403310 DOI: 10.1021/acs.jpclett.9b02047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The hydrogen bond (HB), one of the essential properties of water, tends to link water molecules to form dynamic water clusters. Extrinsic ions could change the size distribution of water clusters by influencing HBs. But the mechanism, especially the influence range of ions on HBs, is still in dispute due to limitation of analytical methods. Herein, we use in situ liquid ToF-SIMS analysis combined with density functional theory calculation to study the influence of different halide anions on HBs at a submicropore confined liquid-vacuum interface. Our experimental results demonstrated that anions show synchronous local and long-range effects on HBs. Specifically, the larger the anion is, the greater degree the long-range HB network and the local hydration number of anions are influenced. More importantly, we found that the long-range effect on the HB network is influenced by nuclear quantum effects, whereas the local effect on water molecules in the first hydration shell is not.
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Affiliation(s)
- Ying-Ya Liu
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
| | - Shao-Ze Zhang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
| | - Yi-Lun Ying
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Hai-Lun Xia
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
| | - Xin Hua
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
| | - Yi-Tao Long
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
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13
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Abstract
Hydration-shell vibrational spectroscopy provides an experimental window into solute-induced water structure changes that mediate aqueous folding, binding, and self-assembly. Decomposition of measured Raman and infrared (IR) spectra of aqueous solutions using multivariate curve resolution (MCR) and related methods may be used to obtain solute-correlated spectra revealing solute-induced perturbations of water structure, such as changes in water hydrogen-bond strength, tetrahedral order, and the presence of dangling (non-hydrogen-bonded) OH groups. More generally, vibrational-MCR may be applied to both aqueous and nonaqueous solutions, including multicomponent mixtures, to quantify solvent-mediated interactions between oily, polar, and ionic solutes, in both dilute and crowded fluids. Combining vibrational-MCR with emerging theoretical modeling strategies promises synergetic advances in the predictive understanding of multiscale self-assembly processes of both biological and technological interest.
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Affiliation(s)
- Dor Ben-Amotz
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
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14
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Wang HW, Graham TR, Mamontov E, Page K, Stack AG, Pearce CI. Countercations Control Local Specific Bonding Interactions and Nucleation Mechanisms in Concentrated Water-in-Salt Solutions. J Phys Chem Lett 2019; 10:3318-3325. [PMID: 31145618 DOI: 10.1021/acs.jpclett.9b01416] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
One of the continuing challenges presented in salt solutions is understanding ion association reactions driving dynamic demixing from solvation, complexation, and solute clustering. The problems understanding this phenomenon are exacerbated in the highly concentrated water-in-salt solutions, where the deficiency of water leads to a dramatic retardation of water solvent and formation of extended solvent-solute clustering networks. By probing microscopic dynamics of water and prenucleation clusters using quasi-elastic neutron scattering and proton nuclear magnetic resonance spectroscopy, we observed contrasting mechanistic specifics of ion-water mobilities in highly concentrated Na+- versus K+-based aluminate solutions (diffusion coefficients of 0.2 vs 2.6 × 10-10 m2 s-1 at 293 K, respectively). The magnitude of the differences is far beyond countercations acting as simple innocent charge-balancing species or water solvents functioning as a simple medium for ion diffusion. The distinct crystallization mechanisms observed further imply that different prenucleation cluster dynamics can either frustrate or promote crystallization, as described by nonclassical nucleation theory.
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Affiliation(s)
| | - Trent R Graham
- Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | | | | | | | - Carolyn I Pearce
- Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
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