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The Structure of the Electric Double Layer of the Protic Ionic Liquid [Dema][TfO] Analyzed by Atomic Force Spectroscopy. Int J Mol Sci 2021; 22:ijms222312653. [PMID: 34884462 PMCID: PMC8658030 DOI: 10.3390/ijms222312653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 12/05/2022] Open
Abstract
Protic ionic liquids are promising electrolytes for fuel cell applications. They would allow for an increase in operation temperatures to more than 100 °C, facilitating water and heat management and, thus, increasing overall efficiency. As ionic liquids consist of bulky charged molecules, the structure of the electric double layer significantly differs from that of aqueous electrolytes. In order to elucidate the nanoscale structure of the electrolyte–electrode interface, we employ atomic force spectroscopy, in conjunction with theoretical modeling using molecular dynamics. Investigations of the low-acidic protic ionic liquid diethylmethylammonium triflate, in contact with a platinum (100) single crystal, reveal a layered structure consisting of alternating anion and cation layers at the interface, as already described for aprotic ionic liquids. The structured double layer depends on the applied electrode potential and extends several nanometers into the liquid, whereby the stiffness decreases with increasing distance from the interface. The presence of water distorts the layering, which, in turn, significantly changes the system’s electrochemical performance. Our results indicate that for low-acidic ionic liquids, a careful adjustment of the water content is needed in order to enhance the proton transport to and from the catalytic electrode.
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Wang D, Hu Z, Peng G, Yin Y. Surface Energy of Curved Surface Based on Lennard-Jones Potential. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:686. [PMID: 33803453 PMCID: PMC7998149 DOI: 10.3390/nano11030686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/05/2021] [Accepted: 03/05/2021] [Indexed: 01/14/2023]
Abstract
Although various phenomena have confirmed that surface geometry has an impact on surface energy at micro/nano scales, determining the surface energy on micro/nano curved surfaces remains a challenge. In this paper, based on Lennard-Jones (L-J) pair potential, we study the geometrical effect on surface energy with the homogenization hypothesis. The surface energy is expressed as a function of local principle curvatures. The accuracy of curvature-based surface energy is confirmed by comparing surface energy on flat surface with experimental results. Furthermore, the surface energy for spherical geometry is investigated and verified by the numerical experiment with errors within 5%. The results show that (i) the surface energy will decrease on a convex surface and increase on a concave surface with the increasing of scales, and tend to the value on flat surface; (ii) the effect of curvatures will be obvious and exceed 5% when spherical radius becomes smaller than 5 nm; (iii) the surface energy varies with curvatures on sinusoidal surfaces, and the normalized surface energy relates with the ratio of wave height to wavelength. The curvature-based surface energy offers new insights into the geometrical and scales effect at micro/nano scales, which provides a theoretical direction for designing NEMS/MEMS.
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Affiliation(s)
- Dan Wang
- Key Laboratory of Mechanics and Control of Mechanical Structures, Interdisciplinary Research Institute, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China;
| | - Zhili Hu
- Key Laboratory of Mechanics and Control of Mechanical Structures, Interdisciplinary Research Institute, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China;
| | - Gang Peng
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, China; (G.P.); (Y.Y.)
| | - Yajun Yin
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, China; (G.P.); (Y.Y.)
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Zhang M, Duan S, Luo S, Zhong Y, Yan J, Liu G, Mao B, Tian Z. Structural Exploration of Multilayered Ionic Liquid/Ag Electrode Interfaces by Atomic Force Microscopy and Surface‐Enhanced Raman Spectroscopy. ChemElectroChem 2020. [DOI: 10.1002/celc.202001294] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Meng Zhang
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
| | - Sai Duan
- Collaborative Innovation Center of Chemistry for Energy Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials MOE Key Laboratory of Computational Physical Sciences Department of Chemistry Fudan University Shanghai 200433 P. R. China
| | - Siheng Luo
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
- State Key Laboratory of Marine Environmental Science Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies Center for Marine Environmental Chemistry & Toxicology College of the Environment and Ecology Xiamen University Xiamen 361102 China
| | - Yunxin Zhong
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
| | - Jiawei Yan
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
| | - Guokun Liu
- State Key Laboratory of Marine Environmental Science Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies Center for Marine Environmental Chemistry & Toxicology College of the Environment and Ecology Xiamen University Xiamen 361102 China
| | - Bingwei Mao
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
| | - Zhongqun Tian
- State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
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Takenaka N, Inagaki T, Shimada T, Yamada Y, Nagaoka M, Yamada A. Theoretical analysis of electrode-dependent interfacial structures on hydrate-melt electrolytes. J Chem Phys 2020; 152:124706. [PMID: 32241124 DOI: 10.1063/5.0003196] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aqueous electrolytes have the potential to overcome some of the safety issues associated with current Li-ion batteries intended for large-scale applications such as stationary use. We recently discovered a lithium-salt dihydrate melt, viz., Li(TFSI)0.7(BETI)0.3·2H2O, which can provide a wide potential window of over 3 V; however, its reductive stability strongly depends on the electrode material. To understand the underlying mechanism, the interfacial structures on several electrodes (C, Al, and Pt) were investigated by conducting molecular dynamics simulation under the constraint of the electrode potential. The results showed that the high adsorption force on the surface of the metal electrodes is responsible for the increased water density, thus degrading the reductive stability of the electrolyte. Notably, the anion orientation on Pt at a low potential is unfavorable for the formation of a stable anion-derived solid electrolyte interphase, thus promoting hydrogen evolution. Hence, the interfacial structures that depend on the material and potential of the electrode mainly determine the reductive stability of hydrate-melt electrolytes.
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Affiliation(s)
- Norio Takenaka
- Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Taichi Inagaki
- Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Tatau Shimada
- Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yuki Yamada
- Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Masataka Nagaoka
- ESICB, Kyoto University, Kyodai Katsura, Nishikyo-ku, Kyoto 615-8520, Japan
| | - Atsuo Yamada
- Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Vishnubhotla SB, Chen R, Khanal SR, Li J, Stach EA, Martini A, Jacobs TDB. Quantitative measurement of contact area and electron transport across platinum nanocontacts for scanning probe microscopy and electrical nanodevices. NANOTECHNOLOGY 2019; 30:045705. [PMID: 30479311 DOI: 10.1088/1361-6528/aaebd6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Conductive modes of atomic force microscopy are widely used to characterize the electronic properties of materials, and in such measurements, contact size is typically determined from current flow. Conversely, in nanodevice applications, the current flow is predicted from the estimated contact size. In both cases, it is very common to relate the contact size and current flow using well-established ballistic electron transport theory. Here we performed 19 electromechanical tests of platinum nanocontacts with in situ transmission electron microscopy to measure contact size and conductance. We also used molecular dynamics simulations of matched nanocontacts to investigate the nature of contact on the atomic scale. Together, these tests show that the ballistic transport equations under-predict the contact size by more than an order of magnitude. The measurements suggest that the low conductance of the contact cannot be explained by the scattering of electrons at defects nor by patchy contact due to surface roughness; instead, the lower-than-expected contact conductance is attributed to approximately a monolayer of insulating surface species on the platinum. Surprisingly, the low conductance persists throughout loading and even after significant sliding of the contact in vacuum. We apply tunneling theory and extract best-fit barrier parameters that describe the properties of this surface layer. The implications of this investigation are that electron transport in device-relevant platinum nanocontacts can be significantly limited by the presence and persistence of surface species, resulting in current flow that is better described by tunneling theory than ballistic electron transport, even for cleaned pure-platinum surfaces and even after loading and sliding in vacuum.
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Affiliation(s)
- Sai Bharadwaj Vishnubhotla
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Rimei Chen
- Department of Mechanical Engineering, University of California-Merced, Merced, CA, United States of America
| | - Subarna R Khanal
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Jing Li
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, United States of America
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY, United States of America
| | - Eric A Stach
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, United States of America
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Ashlie Martini
- Department of Mechanical Engineering, University of California-Merced, Merced, CA, United States of America
| | - Tevis D B Jacobs
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United States of America
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Inagaki T, Nagaoka M. Electrode polarization effects on interfacial kinetics of ionic liquid at graphite surface: An extended lagrangian-based constant potential molecular dynamics simulation study. J Comput Chem 2019; 40:2131-2145. [PMID: 31155755 DOI: 10.1002/jcc.25865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/01/2019] [Accepted: 05/10/2019] [Indexed: 01/02/2023]
Abstract
Computational models including electrode polarization can be essential to study electrode/electrolyte interfacial phenomena more realistically. We present here a constant-potential classical molecular dynamics simulation method based on the extended Lagrangian formulation where the fluctuating electrode atomic charges are treated as independent dynamical variables. The method is applied to a graphite/ionic liquid system for the validation and the interfacial kinetics study. While the correct adiabatic dynamics is achieved with a sufficiently small fictitious mass of charge, static properties have been shown to be almost insensitive to the fictitious mass. As for the kinetics study, electrical double layer (EDL) relaxation and ion desorption from the electrode surface are considered. We found that the polarization slows EDL relaxation greatly whereas it has little impact on the ion desorption kinetics. The findings suggest that the polarization is essential to estimate the kinetics in nonequilibrium processes, not in equilibrium. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Taichi Inagaki
- Graduate School of Informatics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.,Institute for Molecular Science, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Masataka Nagaoka
- Graduate School of Informatics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.,Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Honmachi, Kawaguchi, 332-0012, Japan
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Brault P, Neyts EC. Molecular dynamics simulations of supported metal nanocatalyst formation by plasma sputtering. Catal Today 2015. [DOI: 10.1016/j.cattod.2015.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Li R, Wang L, Yue Q, Li H, Xu S, Liu J. Insights into the adsorption of oxygen and water on low-index Pt surfaces by molecular dynamics simulations. NEW J CHEM 2014. [DOI: 10.1039/c3nj01314f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Duan S, Xu X, Luo Y, Hermansson K, Tian ZQ. Thermal effects on electronic properties of CO/Pt(111) in water. Phys Chem Chem Phys 2013; 15:13619-27. [DOI: 10.1039/c3cp51545a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Morrow BH, Striolo A. Assessing how metal–carbon interactions affect the structure of supported platinum nanoparticles. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020902787812] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Morrow BH, Striolo A. Platinum nanoparticles on carbonaceous materials: the effect of support geometry on nanoparticle mobility, morphology, and melting. NANOTECHNOLOGY 2008; 19:195711. [PMID: 21825729 DOI: 10.1088/0957-4484/19/19/195711] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Molecular dynamics simulations have been used to investigate the morphology and mobility of platinum nanoparticles of various sizes supported by carbon materials. The embedded-atom method was used to model Pt-Pt interactions, and the Lennard-Jones potential was used to model the Pt-C interactions. The C atoms in the supports were held fixed during the simulations. The supports considered were a single graphite sheet and three bundles of carbon nanotubes. Three sizes of Pt nanoparticles were considered: 130 atoms, 249 atoms, and 498 atoms (Pt(130), Pt(249), and Pt(498) respectively). It was found that for all three sizes, diffusion coefficients were approximately one order of magnitude higher for graphite-supported nanoparticles than for carbon nanotube-supported nanoparticles. In addition, increasing the size of the nanoparticle decreased its diffusion coefficient, with Pt(130) having the highest and Pt(498) the lowest diffusion coefficients. More interestingly, we found that for the Pt nanoparticles of all three sizes the diffusion coefficient increases as temperature increases, reaches a maximum at the melting temperature of the nanoparticle, and then decreases. The melting temperature was found to be strongly dependent on the particle size, but only slightly dependent on the features of the supports. While the size of the nanoparticle was seen to affect the particles' mobility, it did not significantly affect their structure. The nanoparticles supported by graphite have density profiles that indicate a highly ordered, fcc-like structure, while the particles supported by carbon nanotubes have a more disordered structure. An order parameter confirms that the nanoparticles' structure depends on the support morphology.
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Affiliation(s)
- Brian H Morrow
- School of Chemical, Biological and Materials Engineering, The University of Oklahoma, Norman, OK 73019, USA
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Chen J, Chan KY. Size-dependent mobility of platinum cluster on a graphite surface. MOLECULAR SIMULATION 2005. [DOI: 10.1080/08927020500134292] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Chui YH, Chan KY. Structures and Energetics of Platinum–Cobalt Bimetallic Clusters. MOLECULAR SIMULATION 2004. [DOI: 10.1080/08927020412331279929] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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