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Bista P, Ratschow AD, Butt HJ, Weber SAL. High Voltages in Sliding Water Drops. J Phys Chem Lett 2023; 14:11110-11116. [PMID: 38052008 PMCID: PMC10726385 DOI: 10.1021/acs.jpclett.3c02864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023]
Abstract
Water drops on insulating hydrophobic substrates can generate electric potentials of kilovolts upon sliding for a few centimeters. We show that the drop saturation voltage corresponds to an amplified value of the solid-liquid surface potential at the substrate. The amplification is given by the substrate geometry, the drop and substrate dielectric properties, and the Debye length within the liquid. Next to enabling an easy and low-cost way to measure surface- and zeta- potentials, the high drop voltages have implications for energy harvesting, droplet microfluidics, and electrostatic discharge protection.
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Affiliation(s)
- Pravash Bista
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Aaron D. Ratschow
- Institute
for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Strasse 10, Darmstadt 64289, Germany
| | - Hans-Jürgen Butt
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Stefan A. L. Weber
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physics, Johannes Gutenberg University, Staudingerweg 10, Mainz 55128, Germany
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2
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Kowacz M, Withanage S, Niestępski S. Voltage and concentration gradients across membraneless interface generated next to hydrogels: relation to glycocalyx. SOFT MATTER 2023; 19:7528-7540. [PMID: 37750247 DOI: 10.1039/d3sm00889d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Next to many hydrophilic surfaces, including those of biological cells and tissues, a layer of water that effectively excludes solutes and particles can be generated. This interfacial water is the subject of research aiming for practical applications such as removal of salts, pathogens or manipulation of biomolecules. However, the exact mechanism of its creation is still elusive because its persistence and extension contradict hydrogen-bond dynamics and electric double layer predictions. The experimentally recorded negative voltage of this interfacial water remains to be properly explained. Even less is known about the nature of such water layers in biological systems. We present experimental evidence for ion and particle exclusion as a result of separation of ionic charges with distinct diffusion rates across a liquid junction at the gel/water interface and the subsequent repulsion of ions of a given sign by a like-charged gel surface. Gels represent features of biological interfaces (in terms of functional groups and porosity) and are subject to biologically relevant chemical triggers. Our results show that gels with -OSO3- and -COO- groups can effectively generate ion- and particle-depleted regions of water reaching over 100 μm and having negative voltage up to -30 mV. Exclusion distance and electric potential depend on the liquid junction potential at the gel/water interface and on the concentration gradient at the depleted region/bulk interface, respectively. The voltage and extension of these ion- and particle-depleted water layers can be effectively modified by CO2 (respiratory gas) or KH2PO4 (cell metabolite). Possible implications pertain to biologically unstirred water layers and a cell's bioenergetics.
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Affiliation(s)
- Magdalena Kowacz
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, Tuwima 10, 10-748 Olsztyn, Poland.
| | - Sinith Withanage
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, Tuwima 10, 10-748 Olsztyn, Poland.
| | - Sebastian Niestępski
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, Tuwima 10, 10-748 Olsztyn, Poland.
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3
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Damasceno JPV, Kubota LT. The Electronic Origin of the Zeta Potential is Supported by the Redox Mechanism on an Aqueous Dispersion of Exfoliated Graphite. Angew Chem Int Ed Engl 2022; 61:e202214995. [PMID: 36315162 DOI: 10.1002/anie.202214995] [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: 10/11/2022] [Indexed: 11/06/2022]
Abstract
Herein we have proposed that a redox mechanism can produce surface charges and negative zeta potential on an aqueous graphite dispersion. Graphite was kept in contact with a concentrated ammonia aqueous solution, washed, and exfoliated in water, resulting in a dispersion with lyophobic nature. Ammonia treatment did not provide functional groups or nitrogen doping to graphite. Moreover, this material was washed twice before sonication to remove most hydroxide. Therefore, neither functional groups, nitrogen atoms, nor hydroxide excess is responsible for the zeta potential. Kelvin probe force microscopy has shown that the ammonia-treated and exfoliated graphite has higher Fermi level than the water-treated material, indicating that the contact between ammonia and graphite promotes redox reactions that provide electrons to graphite. These electrons raise the Fermi level of graphite and generate the negative zeta potential, consequently, they account for the colloidal stability.
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Affiliation(s)
- João Paulo Vita Damasceno
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, São Paulo, 13084-971, Brazil
| | - Lauro Tatsuo Kubota
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, São Paulo, 13084-971, Brazil
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4
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Damasceno JPV, Kubota LT. The Electronic Origin of the Zeta Potential is Supported by the Redox Mechanism on an Aqueous Dispersion of Exfoliated Graphite. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202214995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- João Paulo Vita Damasceno
- Department of Analytical Chemistry Institute of Chemistry University of Campinas P.O. Box 6154 Campinas São Paulo 13084-971 Brazil
| | - Lauro Tatsuo Kubota
- Department of Analytical Chemistry Institute of Chemistry University of Campinas P.O. Box 6154 Campinas São Paulo 13084-971 Brazil
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5
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Nag S, Tomo Y, Teshima H, Takahashi K, Kohno M. Dynamic interplay between interfacial nanobubbles: oversaturation promotes anisotropic depinning and bubble coalescence. Phys Chem Chem Phys 2021; 23:24652-24660. [PMID: 34704571 DOI: 10.1039/d1cp03451k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Probing the dynamics of nanobubbles is essential to understand their longevity and behavior. Importantly, such an observation requires tools and techniques having high temporal resolutions to capture the intrinsic characteristics of the nanobubbles. In this work, we have used the in situ liquid-phase electron microscopy (LPEM) technique to gain insights into nanobubbles' behavior and their interfacial dynamics. Interestingly, we could observe a freely growing-shrinking nanobubble and a pinned nanobubble under the same experimental conditions, suggesting the possibility of multiple nanobubble stabilization theories and pathways. Remarkably, the study reveals that a freely growing-shrinking nanobubble induces anisotropic depinning in the three-phase contact line of a strongly pinned neighboring nanobubble. The anisotropic depinning is attributed to the differential local gas saturation levels, depending on the relative positioning of the freely growing-shrinking nanobubble. Furthermore, we also observed a unique pull-push phenomenon exhibited by the nanobubble's interfaces, which is attributed to the van der Waals interactions and the electric double layer collectively. The role of the electric double layer in suppressing and delaying the merging is also highlighted in this study. The present work aims to reveal the role of locally varying gas saturation in the depinning of nanobubbles, their longevity due to the electric double layer, and the consequent coalescence, which is crucial to understand the behavior of the nanobubbles. Our findings will essentially contribute to the understanding of these novel nanoscale gaseous domains and their dynamics.
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Affiliation(s)
- Sarthak Nag
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan. .,International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
| | - Yoko Tomo
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan.
| | - Hideaki Teshima
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan.,Department of Aeronautics and Astronautics, Kyushu University, Fukuoka 819-0395, Japan
| | - Koji Takahashi
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan.,Department of Aeronautics and Astronautics, Kyushu University, Fukuoka 819-0395, Japan
| | - Masamichi Kohno
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan. .,International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
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Zhang J, Coote ML, Ciampi S. Electrostatics and Electrochemistry: Mechanism and Scope of Charge-Transfer Reactions on the Surface of Tribocharged Insulators. J Am Chem Soc 2021; 143:3019-3032. [DOI: 10.1021/jacs.0c11006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jinyang Zhang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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7
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Helseth LE. Influence of Salt Concentration on Charge Transfer When a Water Front Moves across a Junction between a Hydrophobic Dielectric and a Metal Electrode. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8002-8008. [PMID: 32559100 DOI: 10.1021/acs.langmuir.0c01358] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An energy-harvesting device based on water moving across the junction between a hydrophobic dielectric and a metal electrode is demonstrated. The charge transfer due to contact electrification as the junction is dipped vertically into water is investigated. Experiments combined with finite element simulations reveal how the electrode voltage changes during the dipping process. Moreover, the charge transfer observed for a range of salt concentrations is studied, and it is found that there exists an optimal salt concentration which allows maximum charge transfer. It is suggested that these results can be understood because of the additional charge removal from the diffuse electrical double layer at the hydrophobic surface. It is demonstrated that by tuning the salt concentration, one can harvest more than 3 times the electrical power as compared with pure water.
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Affiliation(s)
- L E Helseth
- Department of Physics and Technology, University of Bergen, Allegaten 55, 5020 Bergen, Norway
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8
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Zhang J, Ciampi S. Shape and Charge: Faraday's Ice Pail Experiment Revisited. ACS CENTRAL SCIENCE 2020; 6:611-612. [PMID: 32490177 PMCID: PMC7256939 DOI: 10.1021/acscentsci.0c00298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Jinyang Zhang
- School of Molecular and Life Sciences,
Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences,
Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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9
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Zhang J, Su C, Rogers FJM, Darwish N, Coote ML, Ciampi S. Irreproducibility in the triboelectric charging of insulators: evidence of a non-monotonic charge versus contact time relationship. Phys Chem Chem Phys 2020; 22:11671-11677. [DOI: 10.1039/d0cp01317j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Contact electrification: irreproducibility of triboelectric charging magnitudes. Using Faraday pail measurements we show that a monotonous charging slope holds only left or right of a material-specific charge-peak point.
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Affiliation(s)
- Jinyang Zhang
- School of Molecular and Life Sciences
- Curtin Institute of Functional Molecules and Interfaces
- Curtin University
- Bentley
- Australia
| | - Chao Su
- School of Energy and Power Engineering
- Jiangsu University of Science and Technology
- Zhenjiang 212003
- P. R. China
| | - Fergus J. M. Rogers
- ARC Centre of Excellence for Electromaterials Science
- Research School of Chemistry
- Australian National University
- Canberra
- Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences
- Curtin Institute of Functional Molecules and Interfaces
- Curtin University
- Bentley
- Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science
- Research School of Chemistry
- Australian National University
- Canberra
- Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences
- Curtin Institute of Functional Molecules and Interfaces
- Curtin University
- Bentley
- Australia
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