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Zhang Y, Zhu X, Wood JA, Lohse D. Threshold current density for diffusion-controlled stability of electrolytic surface nanobubbles. Proc Natl Acad Sci U S A 2024; 121:e2321958121. [PMID: 38748584 PMCID: PMC11126992 DOI: 10.1073/pnas.2321958121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/29/2024] [Indexed: 05/27/2024] Open
Abstract
Understanding the stability mechanism of surface micro/nanobubbles adhered to gas-evolving electrodes is essential for improving the efficiency of water electrolysis, which is known to be hindered by the bubble coverage on electrodes. Using molecular simulations, the diffusion-controlled evolution of single electrolytic nanobubbles on wettability-patterned nanoelectrodes is investigated. These nanoelectrodes feature hydrophobic islands as preferential nucleation sites and allow the growth of nanobubbles in the pinning mode. In these simulations, a threshold current density distinguishing stable nanobubbles from unstable nanobubbles is found. When the current density remains below the threshold value, nucleated nanobubbles grow to their equilibrium states, maintaining their nanoscopic size. However, for the current density above the threshold value, nanobubbles undergo unlimited growth and can eventually detach due to buoyancy. Increasing the pinning length of nanobubbles increases the degree of nanobubble instability. By connecting the current density with the local gas oversaturation, an extension of the stability theory for surface nanobubbles [Lohse and Zhang, Phys. Rev. E 91, 031003(R) (2015)] accurately predicts the nanobubble behavior found in molecular simulations, including equilibrium contact angles and the threshold current density. For larger systems that are not accessible to molecular simulations, continuum numerical simulations with the finite difference method combined with the immersed boundary method are performed, again demonstrating good agreement between numerics and theories.
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Affiliation(s)
- Yixin Zhang
- Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics and Johannes Martinus Burgers Centre for Fluid Dynamics, University of Twente, 7500 AEEnschede, The Netherlands
| | - Xiaojue Zhu
- Max Planck Institute for Solar System Research, 37077Göttingen, Germany
| | - Jeffery A. Wood
- Membrane Science and Technology Cluster, MESA+ Institute for Nanotechnology, University of Twente, 7500 AEEnschede, The Netherlands
| | - Detlef Lohse
- Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics and Johannes Martinus Burgers Centre for Fluid Dynamics, University of Twente, 7500 AEEnschede, The Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077Göttingen, Germany
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Zhang H, Ma Y, Huang M, Mutschke G, Zhang X. Solutal Marangoni force controls lateral motion of electrolytic gas bubbles. SOFT MATTER 2024; 20:3097-3106. [PMID: 38333960 DOI: 10.1039/d3sm01646c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Electrochemical gas-evolving reactions have been widely used for industrial energy conversion and storage processes. Gas bubbles form frequently at the electrode surface due to a small gas solubility, thereby reducing the effective reaction area and increasing the over-potential and ohmic resistance. However, the growth and motion mechanisms for tiny gas bubbles on the electrode remains elusive. Combining molecular dynamics (MD) and fluid dynamics simulations (CFD), we show that there exists a lateral solutal Marangoni force originating from an asymmetric distribution of dissolved gas near the bubble. Both MD and CFD simulations deliver a similar magnitude of the Marangoni force of ∼0.01 nN acting on the bubble. We demonstrate that this force may lead to lateral bubble oscillations and analyze the phenomenon of dynamic self-pinning of bubbles at the electrode boundary.
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Affiliation(s)
- Hongguang Zhang
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Yunqing Ma
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Mengyuan Huang
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
- Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.
| | - Gerd Mutschke
- Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.
| | - Xianren Zhang
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
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Liu T, Zhao Y, Zhai T. Does a Higher Density of Active Sites Indicate a Higher Reaction Rate? J Am Chem Soc 2024; 146:6461-6465. [PMID: 38415580 DOI: 10.1021/jacs.3c14625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
A consensus view in catalysis is that a higher density of catalytically active sites indicates a higher reaction rate. Using molecular dynamics simulations capable of mimicking the electrochemical formation of gas molecules, we herein demonstrate that this view is problematic for electrocatalytic gas production. Our simulation results show that a higher density of catalytic active sites does not necessarily indicate a higher reaction rate─a high density of active sites could lead to a reduction in the rate of reaction. Further analysis reveals that this abnormal phenomenon is ascribed to aggregation of the produced gas molecules near catalytic sites. This work challenges the consensus view and lays the groundwork for better developing gas-producing reaction electrocatalysts.
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Affiliation(s)
- Teng Liu
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yinghe Zhao
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Tianyou Zhai
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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Gadea ED, Molinero V, Scherlis DA. Nanobubble Stability and Formation on Solid-Liquid Interfaces in Open Environments. NANO LETTERS 2023; 23:7206-7212. [PMID: 37490518 DOI: 10.1021/acs.nanolett.3c02261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Are surface nanobubbles transient or thermodynamically stable structures? This question remained controversial until recently, when the stability of gas nanobubbles at solid-liquid interfaces was demonstrated from thermodynamic arguments in closed systems, establishing that bubbles with radii of hundreds of nanometers can be stable at modest supersaturations if the gas amount is finite. Here we develop a grand-canonical description of bubble formation that predicts that nanobubbles can nucleate and remain thermodynamically stable in open boundaries at high supersaturations when pinned to hydrophobic supports as small as a few nanometers. While larger bubbles can also be stable at lower supersaturations, the corresponding barriers are orders of magnitude above kT, meaning that their formation cannot proceed via heterogeneous nucleation on a uniform solid interface but must follow some alternative path. Moreover, we conclude that a source of growth-limiting mechanism, such as pinning or gas availability, is necessary for the thermodynamic stabilization of surface bubbles.
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Affiliation(s)
- Esteban D Gadea
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EHA, Argentina
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0580, United States
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0580, United States
| | - Damián A Scherlis
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EHA, Argentina
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Mondaca-Medina E, García-Carrillo R, Lee H, Wang Y, Zhang H, Ren H. Nanoelectrochemistry in electrochemical phase transition reactions. Chem Sci 2023; 14:7611-7619. [PMID: 37476712 PMCID: PMC10355110 DOI: 10.1039/d3sc01857a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 06/21/2023] [Indexed: 07/22/2023] Open
Abstract
Electrochemical phase transition is important in a range of processes, including gas generation in fuel cells and electrolyzers, as well as in electrodeposition in battery and metal production. Nucleation is the first step in these phase transition reactions. A deep understanding of the kinetics, and mechanism of the nucleation and the structure of the nuclei and nucleation sites is fundamentally important. In this perspective, theories and methods for studying electrochemical nucleation are briefly reviewed, with an emphasis on nanoelectrochemistry and single-entity electrochemistry approaches. Perspectives on open questions and potential future approaches are also discussed.
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Affiliation(s)
- Elías Mondaca-Medina
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
| | - Roberto García-Carrillo
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
| | - Hyein Lee
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
| | - Yufei Wang
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
| | - He Zhang
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
| | - Hang Ren
- Department of Chemistry, The University of Texas at Austin 105 E 24th St Austin TX 78712 USA
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Tian L, Liang J, Gao Y, Gao X, Kang X. Current oscillations from bipolar nanopores for statistical monitoring of hydrogen evolution on a confined electrochemical catalyst. Phys Chem Chem Phys 2023; 25:7629-7633. [PMID: 36857696 DOI: 10.1039/d3cp00055a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Taking advantage of bipolar electrochemistry and a glass nanopipette, continuous single bubbles can be controlled which are generated and detached from a nanometer-sized area of confined electrochemical catalysts. The observed current oscillations offer opportunities to rapidly collect data for the statistical analysis of single-bubble generation on and departure from the catalysts.
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Affiliation(s)
- Lei Tian
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
| | - Jing Liang
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
| | - Yingjie Gao
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
| | - Xiang Gao
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
| | - Xiaofeng Kang
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
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Fundamentals and applications of nanobubbles: A review. Chem Eng Res Des 2022. [DOI: 10.1016/j.cherd.2022.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Chen Q, Zhao J, Deng X, Shan Y, Peng Y. Single-Entity Electrochemistry of Nano- and Microbubbles in Electrolytic Gas Evolution. J Phys Chem Lett 2022; 13:6153-6163. [PMID: 35762985 DOI: 10.1021/acs.jpclett.2c01388] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Gas bubbles are found in diverse electrochemical processes, ranging from electrolytic water splitting to chlor-alkali electrolysis, as well as photoelectrochemical processes. Understanding the intricate influence of bubble evolution on the electrode processes and mass transport is key to the rational design of efficient devices for electrolytic energy conversion and thus requires precise measurement and analysis of individual gas bubbles. In this Perspective, we review the latest advances in single-entity measurement of gas bubbles on electrodes, covering the approaches of voltammetric and galvanostatic studies based on nanoelectrodes, probing bubble evolution using scanning probe electrochemistry with spatial information, and monitoring the transient nature of nanobubble formation and dynamics with opto-electrochemical imaging. We emphasize the intrinsic and quantitative physicochemical interpretation of single gas bubbles from electrochemical data, highlighting the fundamental understanding of the heterogeneous nucleation, dynamic state of the three-phase boundary, and the correlation between electrolytic bubble dynamics and nanocatalyst activities. In addition, a brief discussion of future perspectives is presented.
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Affiliation(s)
- Qianjin Chen
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Jiao Zhao
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Xiaoli Deng
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Yun Shan
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Yu Peng
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
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Hu K, Luo L, Sun X, Li H. Unraveling the effects of gas species and surface wettability on the morphology of interfacial nanobubbles. NANOSCALE ADVANCES 2022; 4:2893-2901. [PMID: 36132003 PMCID: PMC9418701 DOI: 10.1039/d2na00009a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
The morphology of interfacial nanobubbles (INBs) is a crucial but controversial topic in nanobubble research. We carried out atomistic molecular dynamics (MD) simulations to comprehensively study the morphology of INBs controlled by several determinant factors, including gas species, surface wettability, and bubble size. The simulations show that H2, O2 and N2 can all form stable INBs, with the contact angles (CAs, on the liquid side) following the order CA(H2) < CA(N2) < CA(O2), while CO2 prefers to form a gas film (pancake) structure on the substrate. The CA of INBs demonstrates a linear relation with the strength of interfacial interaction; however, a limited bubble CA of ∼25° is found on superhydrophilic surfaces. The high gas density and high internal pressure of the INBs are further confirmed, accompanied by strong interfacial gas enrichment (IGE) behavior. The morphology study of differently sized INBs shows that the internal density of the gas is drastically decreased with the bubble size at the initial stage of bubble nucleation, while the CA remains almost constant. Based on the simulation results, a modified Young's equation is presented for describing the extraordinary morphology of INBs.
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Affiliation(s)
- Kadi Hu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
| | - Liang Luo
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology Beijing 100029 PR China
| | - Xiaoming Sun
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology Beijing 100029 PR China
| | - Hui Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
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Belousov VV, Fedorov SV. Oxygen-Selective Diffusion-Bubbling Membranes with Core-Shell Structure: Bubble Dynamics and Unsteady Effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:8370-8381. [PMID: 34236866 DOI: 10.1021/acs.langmuir.1c00709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Oxygen is the second-largest-volume industrial gas that is mainly produced using cryogenic air separation. However, the state-of-the-art cryogenic technology thermodynamic efficiency has approached a theoretical limit as near as is practicable. Therefore, there is stimulus to develop an alternative technology for efficient oxygen separation from air. Mixed ionic electronic-conducting (MIEC) ceramic membrane-based oxygen separation technology could become this alternative, but commercialization aspects, including cost, have revealed inadequacies in ceramic membrane materials. Currently, diffusion-bubbling molten oxide membrane-based oxygen separation technology is being developed. It is a potentially disruptive technology that would propose an improvement in oxygen purity and a reduction in capital costs. Bubbles play an important role in ensuring the oxygen mass transfer in diffusion-bubbling membranes. However, there is not sufficient understanding of the bubble dynamics. This understanding is important to be able to control transport properties of these membranes and assess their potential for technological application. The aim of this feature article is to highlight the progress made in developing this understanding and specify the directions for future research.
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Affiliation(s)
- Valery V Belousov
- Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49 Leninsky Prospekt, Moscow 119334, Russian Federation
| | - Sergey V Fedorov
- Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49 Leninsky Prospekt, Moscow 119334, Russian Federation
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Ma Y, Guo Z, Chen Q, Zhang X. Dynamic Equilibrium Model for Surface Nanobubbles in Electrochemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2771-2779. [PMID: 33576638 DOI: 10.1021/acs.langmuir.0c03537] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Gas bubbles are ubiquitous in electrochemical processes, particularly in water electrolysis. Due to the development of gas-evolving electrocatalysis and energy conversion technology, a deep understanding of gas bubble behaviors at the electrode surface is highly desirable. In this work, by combining theoretical analysis and molecular simulations, we study the behaviors of a single nanobubble electrogenerated at a nanoelectrode. With the dynamic equilibrium model, the stability criteria for stationary surface nanobubbles are established. We show theoretically that a slight change in either the gas solubility or solute concentration results in various nanobubble dynamic states at a nanoelectrode: contact line pinning in aqueous and ethylene glycol solutions, oscillation of pinning states in dimethyl sulfoxide, and mobile nanobubbles in methanol. The above complex nanobubble behavior at the electrode/electrolyte interface is explained by the competition between gas influx into the nanobubble and outflux from the nanobubble.
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Affiliation(s)
- Yunqing Ma
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhenjiang Guo
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
- Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
| | - Qianjin Chen
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Xianren Zhang
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
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An S, Ranaweera R, Luo L. Harnessing bubble behaviors for developing new analytical strategies. Analyst 2021; 145:7782-7795. [PMID: 33107897 DOI: 10.1039/d0an01497d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gas bubbles are easily accessible and offer many unique characteristic properties of a gas/liquid two-phase system for developing new analytical methods. In this minireview, we discuss the newly developed analytical strategies that harness the behaviors of bubbles. Recent advancements include the utilization of the gas/liquid interfacial activity of bubbles for detection and preconcentration of surface-active compounds; the employment of the gas phase properties of bubbles for acoustic imaging and detection, microfluidic analysis, electrochemical sensing, and emission spectroscopy; and the application of the mass transport behaviors at the gas/liquid interface in gas sensing, biosensing, and nanofluidics. These studies have demonstrated the versatility of gas bubbles as a platform for developing new analytical strategies.
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Affiliation(s)
- Shizhong An
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China
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