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Brosch S, Wiesner F, Decker A, Linkhorst J, Wessling M. Spatio-Temporal Electrowetting and Reaction Monitoring in Microfluidic Gas Diffusion Electrode Elucidates Mass Transport Limitations. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2310427. [PMID: 38386289 DOI: 10.1002/smll.202310427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/15/2024] [Indexed: 02/23/2024]
Abstract
The use of gas diffusion electrodes (GDEs) enables efficient electrochemical CO2 reduction and may be a viable technology in CO2 utilization after carbon capture. Understanding the spatio-temporal phenomena at the triple-phase boundary formed inside GDEs remains a challenge; yet it is critical to design and optimize industrial electrodes for gas-fed electrolyzers. Thus far, transport and reaction phenomena are not yet fully understood at the microscale, among other factors, due to a lack of experimental analysis methods for porous electrodes under operating conditions. In this work, a realistic microfluidic GDE surrogate is presented. Combined with fluorescence lifetime imaging microscopy (FLIM), the methodology allows monitoring of wetting and local pH, representing the dynamic (in)stability of the triple phase boundary in operando. Upon charging the electrode, immediate wetting leads to an initial flooding of the catalyst layer, followed by spatially oscillating pH changes. The micromodel presented gives an experimental insight into transport phenomena within porous electrodes, which is so far difficult to achieve. The methodology and proof of the spatio-temporal pH and wetting oscillations open new opportunities to further comprehend the relationship between gas diffusion electrode properties and electrical currents originating at a given surface potential.
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Affiliation(s)
- Sebastian Brosch
- RWTH Aachen University, Aachener Verfahrenstechnik - Chemical Process Engineering, Forckenbeckstr. 51, 52074, Aachen, Germany
| | - Florian Wiesner
- RWTH Aachen University, Aachener Verfahrenstechnik - Chemical Process Engineering, Forckenbeckstr. 51, 52074, Aachen, Germany
| | - Alexandra Decker
- RWTH Aachen University, Aachener Verfahrenstechnik - Chemical Process Engineering, Forckenbeckstr. 51, 52074, Aachen, Germany
| | - John Linkhorst
- RWTH Aachen University, Aachener Verfahrenstechnik - Chemical Process Engineering, Forckenbeckstr. 51, 52074, Aachen, Germany
- Verfahrenstechnik elektrochemischer Systeme, Technical University Darmstadt, Otto-Berndt-Str. 2, 64287, Darmstadt, Germany
| | - Matthias Wessling
- RWTH Aachen University, Aachener Verfahrenstechnik - Chemical Process Engineering, Forckenbeckstr. 51, 52074, Aachen, Germany
- DWI - Leibnitz Institute for Interactive Materials, Forckenbeckstr. 50, 52074, Aachen, Germany
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2
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Han J, Tu B, An P, Zhang J, Yan Z, Zhang X, Long C, Zhu Y, Yuan Y, Qiu X, Yang Z, Huang X, Yan S, Tang Z. Structuring Cu Membrane Electrode for Maximizing Ethylene Yield from CO 2 Electroreduction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313926. [PMID: 38376851 DOI: 10.1002/adma.202313926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/05/2024] [Indexed: 02/21/2024]
Abstract
Electrocatalytic ethylene (C2H4) evolution from CO2 reduction is an intriguing route to mitigate both the energy and environmental crises; however, to acquire industrially relevant high productivity and selectivity at low energy cost remains to be challenging. Membrane assembly electrode has shown great prospect and tailoring its architecture for maximizing C2H4 yield at minimum voltage with long-term stability becomes critical. Here a freestanding Cu membrane cathode is designed and constructed by electrochemically depositing mesoporous Cu film on Cu foam to simultaneously manage CO2, electron, water, and product transport, which shows an extraordinary C2H4 Faradaic efficiency of 85.6% with a full cell power conversion efficiency of 33% at a current density of 368 mA cm-2, heading the techno-economic viability for electrocatalytic C2H4 production.
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Affiliation(s)
- Jianyu Han
- School of Energy and Environment, Southeast University, Nanjing, 210096, P. R. China
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Bin Tu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Pengfei An
- Institute of High Energy Physics Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Jing Zhang
- Institute of Applied Chemistry, Shanxi University, Taiyuan, 030006, P. R. China
| | - Zhuang Yan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Xiaofei Zhang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Chang Long
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Yanfei Zhu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Yi Yuan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Xueying Qiu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Zhongjie Yang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Xuewei Huang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Shuhao Yan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhiyong Tang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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3
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Shao W, Tlau L, Rai A, Jin J, Zhang Z, Tang B, Groenewold J, Barman J, Zhou G. Hydration Energy-Dependent Ion Intercalation on Graphite and the Asymmetric Electrowetting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 38041643 DOI: 10.1021/acs.langmuir.3c02081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2023]
Abstract
Ion intercalation in graphite is widely used in desalination, batteries, and graphene stripping; it has high value in the fields of industry and research. However, selective ion transport, particularly (de)hydration energy and the hydration shell effect on the intercalation of ions into the graphite interlayer spaces, is still unclear. Here, we report low-voltage ion intercalation as observed by electrowetting on highly oriented pyrolytic graphite of an aqueous drop containing various inorganic salts. The electrowetting response exhibits asymmetric behavior with no contact angle change for the negative polarity and a threshold voltage for the onset of the contact angle change for the positive polarity. To explain the asymmetric electrowetting behavior and quantitatively predict the threshold voltage, we developed a physical model based on the hydration shell energy and size of the ion that undergoes partial breaking/deformation during the co-intercalation into the spaces between graphite layers. Electrowetting experiments using ions with various hydration energies and hydration radii were performed to confirm the prediction of the model. Further, we show a strategy to make the electrowetting response of LiCl drops symmetric via tuning the hydration energy of the Li+ ions using a binary solvent of a glycerol-water mixture. This article will provide an understanding of the hydration (solvation) energy dependence intercalation mechanism in graphite for electrowetting, which underpins various processes such as ion battery applications and the graphene exfoliation process.
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Affiliation(s)
- Wan Shao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Lalnghakmawii Tlau
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh 221005, India
| | - Avijeet Rai
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh 221005, India
| | - Jing Jin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Zhen Zhang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Biao Tang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Jan Groenewold
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Research Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Jitesh Barman
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh 221005, India
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
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4
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Papaderakis AA, Roh JS, Polus K, Yang J, Bissett MA, Walton A, Juel A, Dryfe RAW. Dielectric-free electrowetting on graphene. Faraday Discuss 2023; 246:307-321. [PMID: 37409473 DOI: 10.1039/d3fd00037k] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Electrowetting is a simple way to induce the spreading and retraction of electrolyte droplets. This method is widely used in "device" applications, where a dielectric layer is applied between the electrolyte and the conducting substrate. Recent work, including contributions from our own laboratory, have shown that reversible electrowetting can be achieved directly on conductors. We have shown that graphite surfaces, in particular when combined with highly concentrated electrolyte solutions, show a strong wetting effect. The process is driven by the interactions between the electrolyte ions and the surface, hence models of double-layer capacitance are able to explain changes in the equilibrium contact angles. Herein, we extend the approach to the investigation of electrowetting on graphene samples of varying thickness, prepared by chemical vapor deposition. We show that the use of highly concentrated aqueous electrolytes induces a clear yet subtle electrowetting response due to the adsorption of ions and the suppression of the negative effect introduced by the surface impurities accumulating during the transfer process. The latter have been previously reported to fully hinder electrowetting at lower electrolyte concentrations. An amplified wetting response is recorded in the presence of strongly adsorbed/intercalated anions in both aqueous and non-aqueous electrolytes. The phenomenon is interpreted based on the anion-graphene interactions and their influence on the energetics of the interface. By monitoring the dynamics of wetting, an irreversible behaviour is identified in all cases as a consequence of the irreversibility of anion adsorption and/or intercalation. Finally, the effect of the underlying reactions on the timescales of wetting is also examined.
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Affiliation(s)
- Athanasios A Papaderakis
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Ji Soo Roh
- National Graphene Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Kacper Polus
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jing Yang
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Mark A Bissett
- National Graphene Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Alex Walton
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Anne Juel
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Robert A W Dryfe
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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5
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Baishya R, Sarmah D, Mahanta D, Das SK. Aqueous electrolyte-mediated reversible K + ion insertion into graphite. Phys Chem Chem Phys 2023; 25:24298-24302. [PMID: 37695725 DOI: 10.1039/d3cp02162a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Herein, reversible K+ ion insertion into graphite in an aqueous electrolyte is illustrated. It is shown that more facile diffusion of K+ ions is possible in natural graphite than in pyrolytic graphite.
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Affiliation(s)
| | - Devalina Sarmah
- Department of Physics, Tezpur University, Assam 784028, India.
| | | | - Shyamal K Das
- Department of Physics, Tezpur University, Assam 784028, India.
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6
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Hengsteler J, Kanes KA, Khasanova L, Momotenko D. Beginner's Guide to Micro- and Nanoscale Electrochemical Additive Manufacturing. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2023; 16:71-91. [PMID: 37068744 DOI: 10.1146/annurev-anchem-091522-122334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electrochemical additive manufacturing is an advanced microfabrication technology capable of producing features of almost unlimited geometrical complexity. A unique combination of the capacity to process conductive materials, design freedom, and micro- to nanoscale resolution offered by these electrochemical techniques promises tremendous opportunities for a multitude of future applications spanning microelectronics, sensing, robotics, and energy storage. This review aims to equip readers with the basic principles of electrochemical 3D printing at the small length scale. By describing the basic principles of electrochemical additive manufacturing technology and using the recent advances in the field, this beginner's guide illustrates how controlling the fundamental phenomena that underpin the print process can be used to vary dimensions, morphology, and microstructure of printed structures.
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Affiliation(s)
- Julian Hengsteler
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland
| | - Karuna Aurel Kanes
- Department of Chemistry, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany;
| | - Liaisan Khasanova
- Department of Chemistry, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany;
| | - Dmitry Momotenko
- Department of Chemistry, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany;
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7
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Papaderakis AA, Ejigu A, Yang J, Elgendy A, Radha B, Keerthi A, Juel A, Dryfe RAW. Anion Intercalation into Graphite Drives Surface Wetting. J Am Chem Soc 2023; 145:8007-8020. [PMID: 36977204 PMCID: PMC10103168 DOI: 10.1021/jacs.2c13630] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
The unique layered structure of graphite with its tunable interlayer distance establishes almost ideal conditions for the accommodation of ions into its structure. The smooth and chemically inert nature of the graphite surface also means that it is an ideal substrate for electrowetting. Here, we combine these two unique properties of this material by demonstrating the significant effect of anion intercalation on the electrowetting response of graphitic surfaces in contact with concentrated aqueous and organic electrolytes as well as ionic liquids. The structural changes during intercalation/deintercalation were probed using in situ Raman spectroscopy, and the results were used to provide insights into the influence of intercalation staging on the rate and reversibility of electrowetting. We show, by tuning the size of the intercalant and the stage of intercalation, that a fully reversible electrowetting response can be attained. The approach is extended to the development of biphasic (oil/water) systems that exhibit a fully reproducible electrowetting response with a near-zero voltage threshold and unprecedented contact angle variations of more than 120° within a potential window of less than 2 V.
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Affiliation(s)
- Athanasios A Papaderakis
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Andinet Ejigu
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Jing Yang
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Amr Elgendy
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Egyptian Petroleum Research Institute, 11727 Cairo, Egypt
| | - Boya Radha
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Ashok Keerthi
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Anne Juel
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
| | - Robert A W Dryfe
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U. K
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8
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Papaderakis AA, Al Nasser HA, Chen JY, Juel A, Dryfe RA. Deciphering the mechanism of electrowetting on conductors with immiscible electrolytes. Electrochim Acta 2023. [DOI: 10.1016/j.electacta.2023.142342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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9
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Papaderakis AA, Polus K, Kant P, Box F, Etcheverry B, Byrne C, Quinn M, Walton A, Juel A, Dryfe RAW. Taming Electrowetting Using Highly Concentrated Aqueous Solutions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:21071-21083. [PMID: 36561202 PMCID: PMC9761672 DOI: 10.1021/acs.jpcc.2c06517] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/10/2022] [Indexed: 06/17/2023]
Abstract
Wetting of carbon surfaces is one of the most widespread, yet poorly understood, physical phenomena. Control over wetting properties underpins the operation of aqueous energy-storage devices and carbon-based filtration systems. Electrowetting, the variation in the contact angle with an applied potential, is the most straightforward way of introducing control over wetting. Here, we study electrowetting directly on graphitic surfaces with the use of aqueous electrolytes to show that reversible control of wetting can be achieved and quantitatively understood using models of the interfacial capacitance. We manifest that the use of highly concentrated aqueous electrolytes induces a fully symmetric and reversible wetting behavior without degradation of the substrate within the unprecedented potential window of 2.8 V. We demonstrate where the classical "Young-Lippmann" models apply, and break down, and discuss reasons for the latter, establishing relations among the applied bias, the electrolyte concentration, and the resultant contact angle. The approach is extended to electrowetting at the liquid|liquid interface, where a concentrated aqueous electrolyte drives reversibly the electrowetting response of an insulating organic phase with a significantly decreased potential threshold. In summary, this study highlights the beneficial effect of highly concentrated aqueous electrolytes on the electrowettability of carbon surfaces, being directly related to the performance of carbon-based aqueous energy-storage systems and electronic and microfluidic devices.
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Affiliation(s)
- Athanasios A. Papaderakis
- Department
of Chemistry, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
- Henry
Royce Institute, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
| | - Kacper Polus
- Department
of Chemistry, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
- Photon
Science Institute, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
| | - Pallav Kant
- Department
of Physics and Astronomy, Manchester Center for Nonlinear Dynamics, University of Manchester, Oxford Road, ManchesterM13 9PL, United
Kingdom
| | - Finn Box
- Department
of Physics and Astronomy, Manchester Center for Nonlinear Dynamics, University of Manchester, Oxford Road, ManchesterM13 9PL, United
Kingdom
| | - Bruno Etcheverry
- Department
of Physics and Astronomy, Manchester Center for Nonlinear Dynamics, University of Manchester, Oxford Road, ManchesterM13 9PL, United
Kingdom
| | - Conor Byrne
- Department
of Chemistry, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
- Photon
Science Institute, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
| | - Martin Quinn
- Department
of Physics and Astronomy, Manchester Center for Nonlinear Dynamics, University of Manchester, Oxford Road, ManchesterM13 9PL, United
Kingdom
| | - Alex Walton
- Department
of Chemistry, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
- Photon
Science Institute, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
| | - Anne Juel
- Department
of Physics and Astronomy, Manchester Center for Nonlinear Dynamics, University of Manchester, Oxford Road, ManchesterM13 9PL, United
Kingdom
| | - Robert A. W. Dryfe
- Department
of Chemistry, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
- Henry
Royce Institute, University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
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10
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Xie Y, Ou P, Wang X, Xu Z, Li YC, Wang Z, Huang JE, Wicks J, McCallum C, Wang N, Wang Y, Chen T, Lo BTW, Sinton D, Yu JC, Wang Y, Sargent EH. High carbon utilization in CO2 reduction to multi-carbon products in acidic media. Nat Catal 2022. [DOI: 10.1038/s41929-022-00788-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Jeng E, Qi Z, Kashi AR, Hunegnaw S, Huo Z, Miller JS, Bayu Aji LB, Ko BH, Shin H, Ma S, Kuhl KP, Jiao F, Biener J. Scalable Gas Diffusion Electrode Fabrication for Electrochemical CO 2 Reduction Using Physical Vapor Deposition Methods. ACS APPLIED MATERIALS & INTERFACES 2022; 14:7731-7740. [PMID: 35128928 DOI: 10.1021/acsami.1c17860] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electrochemical CO2 reduction (ECR) promises the replacement of fossil fuels as the source of feedstock chemicals and seasonal storage of renewable energy. While much progress has been made in catalyst development and electrochemical reactor design, few studies have addressed the effect of catalyst integration on device performance. Using a microfluidic gas diffusion electrolyzer, we systematically studied the effect of thickness and the morphology of electron beam (EB) and magnetron-sputtered (MS) Cu catalyst coatings on ECR performance. We observed that EB-Cu outperforms MS-Cu in current density, selectivity, and energy efficiency, with 400 nm thick catalyst coatings performing the best. The superior performance of EB-Cu catalysts is assigned to their faceted surface morphology and sharper Cu/gas diffusion layer interface, which increases their hydrophobicity. Tests in a large-scale zero-gap electrolyzer yielded similar product selectivity distributions with an ethylene Faradaic efficiency of 39% at 200 mA/cm2, demonstrating the scalability for industrial ECR applications.
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Affiliation(s)
- Emily Jeng
- Center for Catalytic Science & Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Zhen Qi
- Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Ajay R Kashi
- Twelve Incorporated (formerly Opus 12 Incorporated), 614 Bancroft Way, Berkeley, California 94710 United States
| | - Sara Hunegnaw
- Twelve Incorporated (formerly Opus 12 Incorporated), 614 Bancroft Way, Berkeley, California 94710 United States
| | - Ziyang Huo
- Twelve Incorporated (formerly Opus 12 Incorporated), 614 Bancroft Way, Berkeley, California 94710 United States
| | - John S Miller
- Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Leonardus B Bayu Aji
- Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Byung Hee Ko
- Center for Catalytic Science & Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Haeun Shin
- Center for Catalytic Science & Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Sichao Ma
- Twelve Incorporated (formerly Opus 12 Incorporated), 614 Bancroft Way, Berkeley, California 94710 United States
| | - Kendra P Kuhl
- Twelve Incorporated (formerly Opus 12 Incorporated), 614 Bancroft Way, Berkeley, California 94710 United States
| | - Feng Jiao
- Center for Catalytic Science & Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Juergen Biener
- Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
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12
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Abstract
The surface wettability of catalysts is typically controlled via surface treatments that promote catalytic performance. Here we report on potential-regulated hydrophobicity/hydrophilicity at cobalt-based oxide interfaces with an alkaline solution. The switchable wetting of single particles, directly related to their activity and stability towards the oxygen evolution reaction, was revealed by electrochemical liquid-phase transmission electron microscopy. Analysis of the movement of the liquid in real time revealed distinctive wettability behaviour associated with specific potential ranges. At low potentials, an overall reduction of the hydrophobicity of the oxides was probed. Upon reversible reconstruction towards the surface oxyhydroxide phase, electrowetting was found to cause a change in the interfacial capacitance. At high potentials, the evolution of molecular oxygen, confirmed by operando electron energy-loss spectroscopy, was accompanied by a globally thinner liquid layer. This work directly links the physical wetting with the chemical oxygen evolution reaction of single particles, providing fundamental insights into solid–liquid interfacial interactions of oxygen-evolving oxides. ![]()
Surface treatments can tune catalysts’ wettability, which can be used to promote their catalytic performance. Now, a potential-dependent dynamic wetting behaviour of cobalt-based oxide catalysts is identified before and during the oxygen evolution reaction.
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13
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Wielend D, Salinas Y, Mayr F, Bechmann M, Yumusak C, Neugebauer H, Brüggemann O, Sariciftci NS. Immobilized Poly(anthraquinones) for Electrochemical Energy Storage Applications: Structure‐Property Relations. ChemElectroChem 2021. [DOI: 10.1002/celc.202101315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Dominik Wielend
- Linz Institute for Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Yolanda Salinas
- Institute of Polymer Chemistry (ICP) Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Felix Mayr
- Linz Institute for Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
- Institute of Applied Physics Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Matthias Bechmann
- Institute of Organic Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Cigdem Yumusak
- Linz Institute for Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
- Materials Research Centre Faculty of Chemistry Brno University of Technology Purkyňova 118 612 00 Brno Czech Republic
| | - Helmut Neugebauer
- Linz Institute for Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Oliver Brüggemann
- Institute of Polymer Chemistry (ICP) Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
| | - Niyazi Serdar Sariciftci
- Linz Institute for Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University Linz Altenberger Straße 69 4040 Linz Austria
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14
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Water friction in nanofluidic channels made from two-dimensional crystals. Nat Commun 2021; 12:3092. [PMID: 34035239 PMCID: PMC8149694 DOI: 10.1038/s41467-021-23325-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 04/20/2021] [Indexed: 11/08/2022] Open
Abstract
Membrane-based applications such as osmotic power generation, desalination and molecular separation would benefit from decreasing water friction in nanoscale channels. However, mechanisms that allow fast water flows are not fully understood yet. Here we report angstrom-scale capillaries made from atomically flat crystals and study the effect of confining walls' material on water friction. A massive difference is observed between channels made from isostructural graphite and hexagonal boron nitride, which is attributed to different electrostatic and chemical interactions at the solid-liquid interface. Using precision microgravimetry and ion streaming measurements, we evaluate the slip length, a measure of water friction, and investigate its possible links with electrical conductivity, wettability, surface charge and polarity of the confining walls. We also show that water friction can be controlled using hybrid capillaries with different slip lengths at opposing walls. The reported advances extend nanofluidics' toolkit for designing smart membranes and mimicking manifold machinery of biological channels.
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15
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Mirbagheri N, Campos R, Ferapontova EE. Electrocatalytic Oxidation of Water by OH
−
‐ and H
2
O‐Capped IrO
x
Nanoparticles Electrophoretically Deposited on Graphite and Basal Plane HOPG: Effect of the Substrate Electrode**. ChemElectroChem 2021. [DOI: 10.1002/celc.202100317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Naghmehalsadat Mirbagheri
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
- Department of Microsystems Engineering – IMTEK University of Freiburg Georges-Koehler-Allee 103 79110 Freiburg Germany
| | - Rui Campos
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
- AXES research group and NANOlab Center of Excellence University of Antwerp Groenenborgerlaan 171 2020 Antwerpen Belgium
| | - Elena E. Ferapontova
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
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16
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Ando T, Asai K, Macpherson J, Einaga Y, Fukuma T, Takahashi Y. Nanoscale Reactivity Mapping of a Single-Crystal Boron-Doped Diamond Particle. Anal Chem 2021; 93:5831-5838. [PMID: 33783208 DOI: 10.1021/acs.analchem.1c00053] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Boron-doped diamond (BDD) is most often grown by chemical vapor deposition (CVD) in polycrystalline form, where the electrochemical response is averaged over the whole surface. Deconvoluting the impact of crystal orientation, surface termination, and boron-doped concentration on the electrochemical response is extremely challenging. To tackle this problem, we use CVD to grow isolated single-crystal microparticles of BDD with the crystal facets (100, square-shaped) and (111, triangle-shaped) exposed and combine with hopping mode scanning electrochemical cell microscopy (HM-SECCM) for electrochemical interrogation of the individual crystal faces (planar and nonplanar). Measurements are made on both hydrogen- (H-) and oxygen (O-)-terminated single-crystal facets with two different redox mediators, [Ru(NH3)6]3+/2+ and Fe(CN)64-/3-. Extraction of the half-wave potential from linear sweep and cyclic voltammetric experiments at all measurement (pixel) points shows unequivocally that electron transfer is faster at the H-terminated (111) surface than at the H-terminated (100) face, attributed to boron dopant differences. The most dramatic differences were seen for [Ru(NH3)6]3+/2+ when comparing the O-terminated (100) surface to the H-terminated (100) face. Removal of the H-surface conductivity layer and a potential-dependent density of states were thought to be responsible for the behavior observed. Finally, a bimodal distribution in the electrochemical activity on the as-grown H-terminated polycrystalline BDD electrode is attributed to the dominance of differently doped (100) and (111) facets in the material.
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Affiliation(s)
- Tomohiro Ando
- Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Kai Asai
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Julie Macpherson
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Yasuaki Einaga
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Takeshi Fukuma
- Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa 920-1192, Japan
| | - Yasufumi Takahashi
- Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa 920-1192, Japan.,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
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17
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Wang Q, Xu M, Wang C, Gu J, Hu N, Lyu J, Yao W. Actuation of a Nonconductive Droplet in an Aqueous Fluid by Reversed Electrowetting Effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8152-8164. [PMID: 32571027 DOI: 10.1021/acs.langmuir.0c01161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Manipulation of a conductive droplet by electrowetting has been a popular topic in microfluidics whereby wettability of the droplet on a solid surface is increased by applying a voltage between the conductive droplet and the insulated surface. However, the opposite phenomenon, e.g., decreasing the wettability of a nonconductive droplet and increasing its contact angle (CA) by the reversed electrowetting (REW) effect, has been scarcely reported. Such a process involves not only the transient dynamics of droplet dewetting but also a critical condition for droplet detachment from the adhesive surface. In this work, actuation of a nonconductive droplet in an aqueous surrounding fluid by REW is studied experimentally. Silicone oil is used for the actuated droplet, and filtered water is used as the surrounding fluid. The solid substrate is made of a glass substrate coated with an indium tin oxide (ITO) film and then deposited by a dielectric layer of Parylene C. Potential difference is applied between the substrate and the surrounding fluid, eliminating the disturbance from the top needle on the motion of the droplet. Three different regimes are identified in the full range of operation. An underactuated regime occurs at low applied voltages, in which the CA of the droplet shows a monotonic increase with the increase of voltage (V). The friction coefficient of the contact line decreases with V before the CA saturation (Vs) but shows little change when V > Vs. At high voltages, the contact line of the sessile droplet is contracted excessively by REW. The droplet shows oscillation, and it refers to the overactuated regime. A combined time scale is proposed, and it verifies that the viscous dissipation of the contact line and liquid inertia show comparable contributions in the droplet dynamics. At sufficiently high voltages, the droplet is rejected completely from the surface. A critical equation for the threshold voltage of droplet detachment is built, and its validity is confirmed by experimental results.
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Affiliation(s)
- Qinggong Wang
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, No. 104 Youyi Road, Haidian District, Beijing 100094, China
| | - Meng Xu
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, No. 104 Youyi Road, Haidian District, Beijing 100094, China
- Jilin Province S&T Innovation Center for Physical Simulation and Security of Water Resources and Electric Power Engineering, Changchun Institute of Technology, No. 395 Kuanping Road, Chaoyang District, Changchun 130012, China
| | - Chao Wang
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, No. 104 Youyi Road, Haidian District, Beijing 100094, China
| | - Junping Gu
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, No. 104 Youyi Road, Haidian District, Beijing 100094, China
- Key Laboratory for Thermal Science and Powder Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Nan Hu
- Jilin Province S&T Innovation Center for Physical Simulation and Security of Water Resources and Electric Power Engineering, Changchun Institute of Technology, No. 395 Kuanping Road, Chaoyang District, Changchun 130012, China
| | - Junfu Lyu
- Key Laboratory for Thermal Science and Powder Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Wei Yao
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, No. 104 Youyi Road, Haidian District, Beijing 100094, China
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18
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Iamprasertkun P, Ejigu A, Dryfe RAW. Understanding the electrochemistry of "water-in-salt" electrolytes: basal plane highly ordered pyrolytic graphite as a model system. Chem Sci 2020; 11:6978-6989. [PMID: 34122994 PMCID: PMC8159404 DOI: 10.1039/d0sc01754j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/05/2020] [Indexed: 12/21/2022] Open
Abstract
A new approach to expand the accessible voltage window of electrochemical energy storage systems, based on so-called "water-in-salt" electrolytes, has been expounded recently. Although studies of transport in concentrated electrolytes date back over several decades, the recent demonstration that concentrated aqueous electrolyte systems can be used in the lithium ion battery context has rekindled interest in the electrochemical properties of highly concentrated aqueous electrolytes. The original aqueous lithium ion battery conception was based on the use of concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide, although these electrolytes still possess some drawbacks including cost, toxicity, and safety. In this work we describe the electrochemical behavior of a simple 1 : 1 electrolyte based on highly concentrated aqueous solutions of potassium fluoride (KF). Highly ordered pyrolytic graphite (HOPG) is used as well-defined model carbon to study the electrochemical properties of the electrolyte, as well as its basal plane capacitance, from a microscopic perspective: the KF electrolyte exhibits an unusually wide potential window (up to 2.6 V). The faradaic response on HOPG is also reported using K3Fe(CN)6 as a model redox probe: the highly concentrated electrolyte provides good electrochemical reversibility and protects the HOPG surface from adsorption of contaminants. Moreover, this electrolyte was applied to symmetrical supercapacitors (using graphene and activated carbon as active materials) in order to quantify its performance in energy storage applications. It is found that the activated carbon and graphene supercapacitors demonstrate high gravimetric capacitance (221 F g-1 for activated carbon, and 56 F g-1 for graphene), a stable working voltage window of 2.0 V, which is significantly higher than the usual range of water-based capacitors, and excellent stability over 10 000 cycles. These results provide fundamental insight into the wider applicability of highly concentrated electrolytes, which should enable their application in future of energy storage technologies.
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Affiliation(s)
- Pawin Iamprasertkun
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Andinet Ejigu
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Robert A W Dryfe
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
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19
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Zhou G, Yang A, Wang Y, Gao G, Pei A, Yu X, Zhu Y, Zong L, Liu B, Xu J, Liu N, Zhang J, Li Y, Wang LW, Hwang HY, Brongersma ML, Chu S, Cui Y. Electrotunable liquid sulfur microdroplets. Nat Commun 2020; 11:606. [PMID: 32001696 PMCID: PMC6992759 DOI: 10.1038/s41467-020-14438-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 12/15/2019] [Indexed: 11/08/2022] Open
Abstract
Manipulating liquids with tunable shape and optical functionalities in real time is important for electroactive flow devices and optoelectronic devices, but remains a great challenge. Here, we demonstrate electrotunable liquid sulfur microdroplets in an electrochemical cell. We observe electrowetting and merging of sulfur droplets under different potentiostatic conditions, and successfully control these processes via selective design of sulfiphilic/sulfiphobic substrates. Moreover, we employ the electrowetting phenomena to create a microlens based on the liquid sulfur microdroplets and tune its characteristics in real time through changing the shape of the liquid microdroplets in a fast, repeatable, and controlled manner. These studies demonstrate a powerful in situ optical battery platform for unraveling the complex reaction mechanism of sulfur chemistries and for exploring the rich material properties of the liquid sulfur, which shed light on the applications of liquid sulfur droplets in devices such as microlenses, and potentially other electrotunable and optoelectronic devices.
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Affiliation(s)
- Guangmin Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute & Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Ankun Yang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yifei Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Guoping Gao
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Allen Pei
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Xiaoyun Yu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yangying Zhu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Linqi Zong
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Bofei Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jinwei Xu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Nian Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Jinsong Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yanxi Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Lin-Wang Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Harold Y Hwang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Mark L Brongersma
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Steven Chu
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94303, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
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20
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Tang B, Shao W, Groenewold J, Li H, Feng Y, Xu X, Shui L, Barman J, Zhou G. Transition of interfacial capacitors in electrowetting on a graphite surface by ion intercalation. Phys Chem Chem Phys 2019; 21:26284-26291. [PMID: 31602437 DOI: 10.1039/c9cp04436a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The low voltage electrowetting response of a LiCl aqueous solution on a freshly cleaved surface of highly oriented pyrolytic graphite (HOPG) is presented. For applied voltages below 1 V, the energy stored in the electrical double layer (EDL) is insufficient to drive the spreading of the drop due to the pinning of the three phase contact line at the step edges. Electrochemical impedance spectroscopy shows a dramatic increase in capacitance above 1 V, which provides a sufficient electrowetting force for depinning the contact line, resulting in a subsequent decrease of the contact angle. The transition of the interfacial capacitance from the EDL to the many-fold high capacitance of the pseudocapacitor drives the electrowetting transition on the HOPG surface. The observed changes in the capacitances above 1 V are correlated with the cyclic voltammetry and atomic force microscopy results, which show that the Cl- ions intercalate into the graphite galleries upon acquiring sufficient energy to overcome the van der Waals attraction between the graphene layers through the side of the step edge of the basal planes. To the best of our knowledge, this is the first study on the voltage dependent intercalation mediated transition of interfacial capacitance driving the spreading of an aqueous electrolyte drop on the HOPG surface, which provides a fundamental understanding of the mechanism and opens up potential applications in microfluidics and charge storage technologies.
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Affiliation(s)
- Biao Tang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China.
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21
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Dey R, van Gorcum M, Mugele F, Snoeijer JH. Soft electrowetting. SOFT MATTER 2019; 15:6469-6475. [PMID: 31289803 DOI: 10.1039/c9sm00847k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Electrowetting is a commonly used tool to manipulate sessile drops on hydrophobic surfaces. By applying an external voltage over a liquid and a dielectric-coated surface, one achieves a reduction of the macroscopic contact angles for increasing voltage. The electrostatic forces all play out near the contact line, on a scale of the order of the thickness of the solid dielectric layer. Here we explore the case where the dielectric is a soft elastic layer, which deforms elastically under the effect of electrostatic and capillary forces. The wetting behaviour is quantified by measurements of the static and dynamic contact angles, complemented by confocal microscopy to reveal the elastic deformations. Even though the mechanics near the contact line is highly intricate, the macroscopic contact angles can be understood from global conservation laws in the spirit of Young-Lippmann. The key finding is that, while elasticity has no effect on the static electrowetting angle, the substrate's viscoelasticity completely dictates the spreading dynamics of electrowetting.
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Affiliation(s)
- Ranabir Dey
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Goettingen, Germany. and Physics of Complex Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands
| | - Mathijs van Gorcum
- Physics of Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands.
| | - Frieder Mugele
- Physics of Complex Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands
| | - Jacco H Snoeijer
- Physics of Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands.
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22
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Ionic-surfactant-mediated electro-dewetting for digital microfluidics. Nature 2019; 572:507-510. [PMID: 31435058 DOI: 10.1038/s41586-019-1491-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 07/10/2019] [Indexed: 11/09/2022]
Abstract
The ability to manipulate droplets on a substrate using electric signals1-known as digital microfluidics-is used in optical2,3, biomedical4,5, thermal6 and electronic7 applications and has led to commercially available liquid lenses8 and diagnostics kits9,10. Such electrical actuation is mainly achieved by electrowetting, with droplets attracted towards and spreading on a conductive substrate in response to an applied voltage. To ensure strong and practical actuation, the substrate is covered with a dielectric layer and a hydrophobic topcoat for electrowetting-on-dielectric (EWOD)11-13; this increases the actuation voltage (to about 100 volts) and can compromise reliability owing to dielectric breakdown14, electric charging15 and biofouling16. Here we demonstrate droplet manipulation that uses electrical signals to induce the liquid to dewet, rather than wet, a hydrophilic conductive substrate without the need for added layers. In this electrodewetting mechanism, which is phenomenologically opposite to electrowetting, the liquid-substrate interaction is not controlled directly by electric field but instead by field-induced attachment and detachment of ionic surfactants to the substrate. We show that this actuation mechanism can perform all the basic fluidic operations of digital microfluidics using water on doped silicon wafers in air, with only ±2.5 volts of driving voltage, a few microamperes of current and about 0.015 times the critical micelle concentration of an ionic surfactant. The system can also handle common buffers and organic solvents, promising a simple and reliable microfluidic platform for a broad range of applications.
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23
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Ruiz-Gutiérrez É, Ledesma-Aguilar R. Lattice-Boltzmann Simulations of Electrowetting Phenomena. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4849-4859. [PMID: 30869524 DOI: 10.1021/acs.langmuir.9b00098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
When a voltage difference is applied between a conducting liquid and a conducting (solid) electrode, the liquid is observed to spread on the solid. This phenomenon, generally referred to as electrowetting, underpins a number of interfacial phenomena of interest in applications that range from droplet microfluidics to optics. Here, we present a lattice-Boltzmann method that can simulate the coupled hydrodynamics and electrostatics equations of motion of a two-phase fluid as a means to model the electrowetting phenomena. Our method has the advantage of modeling the electrostatic fields within the lattice-Boltzmann algorithm itself, eliminating the need for a hybrid method. We validate our method by reproducing the static equilibrium configuration of a droplet subject to an applied voltage and show that the apparent contact angle of the drop depends on the voltage following the Young-Lippmann equation up to contact angles of ≈50°. At higher voltages, we observe a saturation of the contact angle caused by the competition between electric and capillary stresses, similar to previous experimental observations. We also study the stability of a dielectric film trapped between a conducting fluid and a solid electrode and find a good agreement with analytical predictions based on lubrication theory. Finally, we investigate the film dynamics at long times and report observations of film breakup and entrapment similar to previously reported experimental results.
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Affiliation(s)
- Élfego Ruiz-Gutiérrez
- Smart Materials and Surfaces Laboratory , Northumbria University , Ellison Building, Ellison Place , Newcastle upon Tyne NE1 8ST , U.K
| | - Rodrigo Ledesma-Aguilar
- Smart Materials and Surfaces Laboratory , Northumbria University , Ellison Building, Ellison Place , Newcastle upon Tyne NE1 8ST , U.K
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24
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Iamprasertkun P, Hirunpinyopas W, Keerthi A, Wang B, Radha B, Bissett MA, Dryfe RAW. Capacitance of Basal Plane and Edge-Oriented Highly Ordered Pyrolytic Graphite: Specific Ion Effects. J Phys Chem Lett 2019; 10:617-623. [PMID: 30672302 DOI: 10.1021/acs.jpclett.8b03523] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Carbon materials are ubiquitous in energy storage; however, many of the fundamental electrochemical properties of carbons are still not fully understood. In this work, we studied the capacitance of highly ordered pyrolytic graphite (HOPG), with the aim of investigating specific ion effects seen in the capacitance of the basal plane and edge-oriented planes of the material. A series of alkali metal cations, from Li+, Na+, K+, Rb+, and Cs+ with chloride as the counterion, were used at a fixed electrolyte concentration. The basal plane capacitance at a fixed potential relative to the potential of zero charge was found to increase from 4.72 to 9.39 μF cm-2 proceeding down Group 1. In contrast, the edge-orientated samples display capacitance ca. 100 times higher than those of the basal plane, attributed to pseudocapacitance processes associated with the presence of oxygen groups and largely independent of cation identity. This work improves understanding of capacitive properties of carbonaceous materials, leading to their continued development for use in energy storage.
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Affiliation(s)
- Pawin Iamprasertkun
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Wisit Hirunpinyopas
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Ashok Keerthi
- School of Physics and Astronomy , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Bin Wang
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Boya Radha
- School of Physics and Astronomy , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Mark A Bissett
- School of Materials , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Robert A W Dryfe
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
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25
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Wan Y, Gao Y, Xia Z. Highly Switchable Adhesion of N-Doped Graphene Interfaces for Robust Micromanipulation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:5544-5553. [PMID: 30648852 DOI: 10.1021/acsami.8b18793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We demonstrated an N-doped graphene interface with highly switchable adhesion and robust micromanipulation capability triggered by external electric signals. Upon applying a small dc or ac electrical bias, this nanotextured surface can collect environmental moisture to form a large number of water bridges between the graphene and target surface, which lead to a drastic change in adhesive force. Turning on and off the electrical bias can control this graphene interface as a robust micro/nanomanipulator to pick up and drop off various micro/nano-objects for precise assembling. Molecular dynamics simulation reveals that the electrically induced electric double layer and ordered icelike structures at the graphene-water interface strengthen the water bridges and consequently enhance force switchability. In addition to the micro-/nanomanipulation, this switchable adhesion may have many technical implications such as climbing robots, sensors, microfluidic devices, and advanced drug delivery.
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Affiliation(s)
- Yiyang Wan
- Department of Materials Science and Engineering, and Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
| | - Yong Gao
- Department of Materials Science and Engineering, and Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
- School of Materials Science and Engineering , Northwestern Polytechnical University , Xi'an , Shaanxi 710072 , P. R. China
| | - Zhenhai Xia
- Department of Materials Science and Engineering, and Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
- School of Materials Science and Engineering , Northwestern Polytechnical University , Xi'an , Shaanxi 710072 , P. R. China
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Bonfante G, Roux-Marchand T, Audry-Deschamps MC, Renaud L, Kleimann P, Brioude A, Maillard M. Polarization mechanisms of dielectric materials at a binary liquid interface: impacts on electrowetting actuation. Phys Chem Chem Phys 2017; 19:30139-30146. [PMID: 29104979 DOI: 10.1039/c7cp06052a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We explored polarization mechanisms at the interface between a dielectric material (an electrolyte) and an insulating liquid, during electrowetting actuation. Native surface charge density due to hydrophobic coating has been measured as an offset voltage for which the contact angle is at its minimum. Surface charge densities as low as 0.023 mC m-2 have been measured using this method, demonstrating that electrowetting can be used as a probe to measure native surface charge density. This effect strongly differs depending on the kind of polarization and is at the origin of major discrepancies between alternative and direct polarization during electrowetting actuation. A new model describing electrowetting actuation is also proposed, leading to a more predictive description as well as useful recommendations on materials to obtain a stable actuation under DC polarization.
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Affiliation(s)
- G Bonfante
- Université de Lyon, Université Claude Bernard LYON1, Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, F-69622 Villeurbanne, France.
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Morooka T, Tahara H, Sagara T. Effect of bromide adsorption on electrowetting of Au electrode with hexadecane. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.08.133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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28
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Kumar S, Sarma B, Dasmahapatra AK, Dalal A, Basu DN, Bandyopadhyay D. Field induced anomalous spreading, oscillation, ejection, spinning, and breaking of oil droplets on a strongly slipping water surface. Faraday Discuss 2017; 199:115-128. [PMID: 28422194 DOI: 10.1039/c6fd00233a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Application of an electric field on an oil droplet floating on the surface of a deionized water bath showed interesting motions such as spreading, oscillation, and ejection. The electric field was generated by connecting a pointed platinum cathode at the top of the oil droplet and a copper anode coated with polymer at the bottom of the water layer. The experimental setup mimicked a conventional electrowetting setup with the exception that the oil was spread on a soft and deformable water isolator. While at relatively lower field intensities we observed spreading of the droplet, at intermediate field intensities the droplet oscillated around the platinum cathode, before ejecting out at a speed as high as ∼5 body lengths per second at even stronger field intensities. The experiments suggested that when the electric field was ramped up abruptly to a particular voltage, any of the spreading, oscillation, or ejection motions of the droplet could be engendered at lower, intermediate and higher field intensities, respectively. However, when the field was ramped up progressively by increasing by a definite amount of voltage per unit time, all three aforementioned motions could be generated simultaneously with the increase in the field intensity. Interestingly, when the aforementioned setup was placed on a magnet, the droplet showed a rotational motion under the influence of the Lorentz force, which was generated because of the coupling of the weak leakage current with the externally applied magnetic field. The spreading, oscillation, ejection, and rotation of the droplet were found to be functions of the oil-water interfacial tension, viscosity, and size of the oil droplet. We developed simple theoretical models to explain the experimental results obtained. Importantly, rotating at a higher speed broke the droplet into a number of smaller ones, owing to the combined influence of the spreading due to the centripetal force and the shear at the oil-water interface. While the oscillatory and rotational motions of the incompressible droplet could be employed as stirrers or impellers inside microfluidic devices for mixing applications, the droplet ejection could be employed for futuristic applications such as payload transport or drug delivery.
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Affiliation(s)
- Sunny Kumar
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India.
| | - Bhaskarjyoti Sarma
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Ahsok Kumar Dasmahapatra
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India. and Centre for Nanotechnology, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Amaresh Dalal
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Dipankar Narayan Basu
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Dipankar Bandyopadhyay
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India. and Centre for Nanotechnology, Indian Institute of Technology Guwahati, Assam 781039, India
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Eaker CB, Joshipura ID, Maxwell LR, Heikenfeld J, Dickey MD. Electrowetting without external voltage using paint-on electrodes. LAB ON A CHIP 2017; 17:1069-1075. [PMID: 28225124 DOI: 10.1039/c6lc01500j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab-on-a-chip and optical devices. To avoid electrochemical reactions, a dielectric often separates the fluid from the electrode, which has the undesired effect of adding processing steps while increasing the voltage necessary for electrowetting. We present a new method to dramatically reduce the complexity of electrode and dielectric fabrication while enabling multiple performance advances. This method relies on a self-oxidizing paint-on liquid-metal electrode that can be fabricated in minutes on rigid, rough, or even elastic substrates, enabling low operation voltages (<1 V), and self-healing upon dielectric breakdown. Furthermore, due to the non-negligible 'potential of zero charge', electrowetting occurs by simply short circuiting the electrodes. This work opens up new application spaces for electrowetting (e.g. stretchable substrates, soft and injectable electrodes) while achieving large changes in contact angle without the need for an external power supply.
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Affiliation(s)
- Collin B Eaker
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
| | - Ishan D Joshipura
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
| | - Logan R Maxwell
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
| | - Jason Heikenfeld
- Department of Electrical Engineering and Computing Systems, University of Cincinnati, Cincinnati, OH 45221-0030, USA
| | - Michael D Dickey
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
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Ounnunkad K, Patten HV, Velický M, Farquhar AK, Brooksby PA, Downard AJ, Dryfe RAW. Electrowetting on conductors: anatomy of the phenomenon. Faraday Discuss 2017; 199:49-61. [DOI: 10.1039/c6fd00252h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We have recently reported that reversible electrowetting can be observed on the basal plane of graphite, without the presence of a dielectric layer, in both liquid/air and liquid/liquid configurations. The influence of carbon structure on the wetting phenomenon is investigated in more detail here. Specifically, it is shown that the adsorption of adventitious impurities on the graphite surface markedly suppresses the electrowetting response. Similarly, the use of pyrolysed carbon films, although exhibiting a roughness below the threshold previously identified as the barrier to wetting on basal plane graphite, does not give a noticeable electrowetting response, which leads us to conclude that specific interactions at the water–graphite interface as well as graphite crystallinity are responsible for the reversible response seen in the latter case. Preliminary experiments on mechanically exfoliated and chemical vapour deposition grown graphene are also reported.
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Affiliation(s)
- Kontad Ounnunkad
- School of Chemistry
- University of Manchester
- Manchester M13 9PL
- UK
- Chiang Mai University
| | | | - Matěj Velický
- School of Chemistry
- University of Manchester
- Manchester M13 9PL
- UK
| | - Anna K. Farquhar
- MacDiarmid Institute for Advanced Materials and Nanotechnology
- Department of Chemistry
- University of Canterbury
- Christchurch 8140
- New Zealand
| | - Paula A. Brooksby
- MacDiarmid Institute for Advanced Materials and Nanotechnology
- Department of Chemistry
- University of Canterbury
- Christchurch 8140
- New Zealand
| | - Alison J. Downard
- MacDiarmid Institute for Advanced Materials and Nanotechnology
- Department of Chemistry
- University of Canterbury
- Christchurch 8140
- New Zealand
| | - Robert A. W. Dryfe
- School of Chemistry
- University of Manchester
- Manchester M13 9PL
- UK
- National Graphene Institute
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31
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Banpurkar AG, Sawane Y, Wadhai SM, Murade CU, Siretanu I, van den Ende D, Mugele F. Spontaneous electrification of fluoropolymer–water interfaces probed by electrowetting. Faraday Discuss 2017; 199:29-47. [DOI: 10.1039/c6fd00245e] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fluoropolymers are widely used as coatings for their robustness, water-repellence, and chemical inertness. In contact with water, they are known to assume a negative surface charge, which is commonly attributed to adsorbed hydroxyl ions. Here, we demonstrate that a small fraction of these ions permanently sticks to surfaces of Teflon AF and Cytop, two of the most common fluoropolymer materials, upon prolonged exposure to water. Electrowetting measurements carried out after aging in water are used to quantify the density of ‘trapped’ charge. Values up to −0.07 and −0.2 mC m−2are found for Teflon AF and for Cytop, respectively, at elevated pH. A similar charge trapping process is also observed upon aging in various non-aqueous polar liquids and in humid air. A careful analysis highlights the complementary nature of electrowetting and streaming potential measurements in quantifying interfacial energy and charge density. We discuss the possible mechanism of charge trapping and highlight the relevance of molecular scale processes for the long term stability and performance of fluoropolymer materials for applications in electrowetting and elsewhere.
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Affiliation(s)
- Arun G. Banpurkar
- Center for Advanced Studies in Materials Science and Condensed Matter Physics
- Department of Physics
- University of Pune
- Pune-411 007
- India
| | - Yogesh Sawane
- Center for Advanced Studies in Materials Science and Condensed Matter Physics
- Department of Physics
- University of Pune
- Pune-411 007
- India
| | - Sandip M. Wadhai
- Center for Advanced Studies in Materials Science and Condensed Matter Physics
- Department of Physics
- University of Pune
- Pune-411 007
- India
| | - C. U. Murade
- Physics of Complex Fluids
- Faculty of Science and Technology
- MESA+ Institutes
- University of Twente
- 7500AE Enschede
| | - Igor Siretanu
- Physics of Complex Fluids
- Faculty of Science and Technology
- MESA+ Institutes
- University of Twente
- 7500AE Enschede
| | - D. van den Ende
- Physics of Complex Fluids
- Faculty of Science and Technology
- MESA+ Institutes
- University of Twente
- 7500AE Enschede
| | - F. Mugele
- Physics of Complex Fluids
- Faculty of Science and Technology
- MESA+ Institutes
- University of Twente
- 7500AE Enschede
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