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Sahil ST, McCardle KM, Le Magueres P, Panetier JA, Jurss JW. Investigations of a Copper(II) Bipyridyl- N-Heterocyclic Carbene Macrocycle for CO 2 Reduction: Apparent Formation of an Imidazolium Carboxylate Intermediate Leading to Demetalation. ACS OMEGA 2024; 9:34555-34566. [PMID: 39157073 PMCID: PMC11325401 DOI: 10.1021/acsomega.4c02520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 07/12/2024] [Accepted: 07/19/2024] [Indexed: 08/20/2024]
Abstract
A copper complex supported by a redox-active bipyridyl-N-heterocyclic carbene based ligand framework is reported. From X-ray crystallography, the tetradentate macrocycle provides a distorted square planar geometry around the copper metal center. The complex was investigated for the electrocatalytic CO2 reduction reaction (CO2RR) in acetonitrile solutions. Electronic structure calculations were performed on the complex and associated intermediates to provide a fundamental understanding of the metal-ligand redox chemistry and are compared to the previously reported nickel and cobalt analogues. Unlike its predecessors, which are active catalysts for the CO2RR, the copper complex decomposes under reducing conditions in the presence of CO2. A novel decomposition route involving coordination of CO2 to an N-heterocyclic carbene (NHC) donor of the macrocyclic ligand is proposed based on density functional theory (DFT) calculations, which is supported by isolation of a putative ligand-CO2 adduct from the electrolyzed solution and its characterization by 1H NMR spectroscopy and mass spectrometry. The noninnocent behavior of the NHC donors presented here may have important implications for the stability and reactivity of other complexes supported by N-heterocyclic carbenes, and further suggests that cooperative and productive pathways involving metal-bound NHCs could be exploited for CO2 reduction.
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Affiliation(s)
- Sha Tamanna Sahil
- Department
of Chemistry and Biochemistry, University
of Mississippi, University, Mississippi 38677, United States
| | - Kaitlin M. McCardle
- Department
of Chemistry, State University of New York
at Binghamton, Binghamton, New York 13902, United States
| | | | - Julien A. Panetier
- Department
of Chemistry, State University of New York
at Binghamton, Binghamton, New York 13902, United States
| | - Jonah W. Jurss
- Department
of Chemistry and Biochemistry, University
of Mississippi, University, Mississippi 38677, United States
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2
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Malavekar D, Pujari S, Jang S, Bachankar S, Kim JH. Recent Development on Transition Metal Oxides-Based Core-Shell Structures for Boosted Energy Density Supercapacitors. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2312179. [PMID: 38593336 DOI: 10.1002/smll.202312179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 02/22/2024] [Indexed: 04/11/2024]
Abstract
In recent years, nanomaterials exploration and synthesis have played a crucial role in advancing energy storage research, particularly in supercapacitor development. Researchers have diversified materials, including metal oxides, chalcogenides, and composites, as well as carbon materials, to enhance energy and power density. Balancing energy density with electrochemical stability remains challenging, driving intensified efforts in advancing electrode materials. This review focuses on recent progress in designing and synthesizing core-shell materials tailored for supercapacitors. The core-shell architecture offers advantages such as increased surface area, redox active sites, electrical conductivity, ion diffusion kinetics, specific capacitance, and cyclability. The review explores the impact of core and shell materials, specifically transition metal oxides (TMOs), on supercapacitor electrochemical behavior. Metal oxide choices, such as cobalt oxide as a preferred core and manganese oxide as a shell, are discussed. The review also highlights characterization techniques for assessing structural, morphological, and electrochemical properties of core-shell materials. Overall, it provides a comprehensive overview of ongoing TMOs-based core-shell material research for supercapacitors, showcasing their potential to enhance energy storage for applications ranging from gadgets to electric vehicles. The review outlines existing challenges and future opportunities in evolving TMOs-based core-shell materials for supercapacitor advancements, holding promise for high-efficiency energy storage devices.
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Affiliation(s)
- Dhanaji Malavekar
- Optoelectronics Convergence Research Center and Department of Materials Science and Engineering, Chonnam National University, 300, Yongbong-Dong, Buk-Gu, Gwangju, 61186, South Korea
| | - Sachin Pujari
- Department of Physics, Yashwantrao Chavan Warana Mahavidyalaya, Warananagar, Kolhapur, 416113, India
| | - Suyoung Jang
- Optoelectronics Convergence Research Center and Department of Materials Science and Engineering, Chonnam National University, 300, Yongbong-Dong, Buk-Gu, Gwangju, 61186, South Korea
| | - Shital Bachankar
- Department of Physics, Yashwantrao Chavan Warana Mahavidyalaya, Warananagar, Kolhapur, 416113, India
| | - Jin Hyeok Kim
- Optoelectronics Convergence Research Center and Department of Materials Science and Engineering, Chonnam National University, 300, Yongbong-Dong, Buk-Gu, Gwangju, 61186, South Korea
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3
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Chen J, Shi Y, Zheng S, Zhao W, Li R, Ye K, Zhao X, Zuo Z, Pan Z, Yang X. Blocking Interfacial Proton Transport via Self-Assembled Monolayer for Hydrogen Evolution-Free Zinc Batteries. Angew Chem Int Ed Engl 2024; 63:e202404825. [PMID: 38647332 DOI: 10.1002/anie.202404825] [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: 03/10/2024] [Revised: 04/11/2024] [Accepted: 04/20/2024] [Indexed: 04/25/2024]
Abstract
Aqueous Zn-ion batteries (ZIBs) are promising next-generation energy storage devices, yet suffer from the issues of hydrogen evolution reaction (HER) and intricate side reactions on the Zn anode surface. The hydrogen (H)-bond networks play a critical role in interfacial proton transport that may closely relate to HER but are rarely investigated. Herein, we report a self-assembled monolayer (SAM) strategy which is constructed by anchoring ionic liquid cations on Ti3C2Tx substrate for HER-free Zn anode. Molecule dynamics simulations reveal that the rationally designed SAM with a high coordination number of water molecules (25-27, 4-6 for Zn2+) largely reduces the interfacial densities of H2O molecules, therefore breaking the connectivity of H-bond networks and blocking proton transport on the interface, by which the HER is suppressed. Then, a series of in situ characterizations demonstrate that negligible amounts of H2 gas are collected from the Zn@SAM-MXene anode. Consequently, the symmetric cell enables a long-cycling life of 3000 h at 1 mA cm-2 and 1000 h at 5 mA cm-2. More significantly, the stable Zn@SAM-MXene films are successfully used for coin full cells showing high-capacity retention of over 94 % after 1000 cycles and large-area (10×5 cm2) pouch cells with desired performance.
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Affiliation(s)
- Jianping Chen
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
| | - Yayun Shi
- State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan, 030024, P. R. China
| | - Songhe Zheng
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
| | - Wanyu Zhao
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Ruimin Li
- State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan, 030024, P. R. China
| | - Ke Ye
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
| | - Xiaoli Zhao
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
| | - Zhijun Zuo
- State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan, 030024, P. R. China
| | - Zhenghui Pan
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
| | - Xiaowei Yang
- School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P. R. China
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
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4
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Pérez-Ramos P, Mateo MA, Elorriaga D, García-Vivó D, Soengas RG, Rodríguez-Solla H. Coordination of azol(in)ium dithiocarboxylate ligands to Au(III): unexpected formation of a novel family of cyclometallated Au(III) complexes, DFT calculations and catalytic studies. Dalton Trans 2024; 53:9433-9440. [PMID: 38758133 DOI: 10.1039/d4dt01184h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
A series of cyclometallated gold(III) complexes 21-27 of general formula [Au(dppta)(azdtc)Cl] (dppta = N,N-diisopropyl-P,P-diphenylphosphinothioic amide-κ2C,S; azdtc = azol(in)ium-2-dithiocarboxylate-κ1S) were prepared and characterized by spectroscopic and diffractometric techniques. Treatment of [Au(dppta)(azdtc)Cl] complexes with methanol led to their quantitative transformation into a novel family of (C^S, S^S)-cyclometallated gold(III) complexes of general formula [Au(dppta)(azmtd)] (azmdt = azol(in)ium-2-(methoxy)methanedithiol-κ2S,S) 28-34. All the [Au(dppta)(azdtc)Cl] complexes 21-27 catalyzed the alkylation of indoles, whereas [Au(dppta)(azmtd)] complexes 28-34 were inactive. Among the synthesized derivatives, complex 22 displayed the highest catalytic activity, leading to a series of functionalized indoles in excellent yields.
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Affiliation(s)
- Paula Pérez-Ramos
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - María A Mateo
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - David Elorriaga
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - Daniel García-Vivó
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - Raquel G Soengas
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - Humberto Rodríguez-Solla
- Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
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5
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Lu Z, Mitra D, Narayan SR, Williams TJ. An Immobilized (Carbene)Nickel Catalyst for Water Oxidation. Polyhedron 2024; 252:116880. [PMID: 38435834 PMCID: PMC10907011 DOI: 10.1016/j.poly.2024.116880] [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] [Indexed: 03/05/2024]
Abstract
The oxygen evolution reaction (OER) of water splitting is essential to electrochemical energy storage applications. While nickel electrodes are widely available heterogeneous OER catalysts, homogeneous nickel catalysts for OER are underexplored. Here we report two carbene-ligated nickel(II) complexes that are exceptionally robust and efficient homogeneous water oxidation catalysts. Remarkably, these novel nickel complexes can assemble a stable thin film onto a metal electrode through poly-imidazole bridges, making them supported heterogeneous electrochemical catalysts that are resilient to leaching and stripping. Unlike molecular catalysts and nanoparticle catalysts, such electrode-supported metal-complex catalysts for OER are rare and have the potential to inspire new designs. The electrochemical OER with our nickel-carbene catalysts exhibits excellent current densities with high efficiency, low Tafel slope, and useful longevity for a base metal catalyst. Our data show that imidazole carbene ligands stay bonded to the nickel(II) centers throughout the catalysis, which allows the facile oxygen evolution.
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Affiliation(s)
- Zhiyao Lu
- Donald P. and Katherine B. Loker Hydrocarbon Institute, Wrigley Institute for Environment and Sustainability, and Department of Chemistry, University of Southern California, Los Angeles, California, 90089-1661, United States
| | - Debanjan Mitra
- Donald P. and Katherine B. Loker Hydrocarbon Institute, Wrigley Institute for Environment and Sustainability, and Department of Chemistry, University of Southern California, Los Angeles, California, 90089-1661, United States
| | - Sri R. Narayan
- Donald P. and Katherine B. Loker Hydrocarbon Institute, Wrigley Institute for Environment and Sustainability, and Department of Chemistry, University of Southern California, Los Angeles, California, 90089-1661, United States
| | - Travis J. Williams
- Donald P. and Katherine B. Loker Hydrocarbon Institute, Wrigley Institute for Environment and Sustainability, and Department of Chemistry, University of Southern California, Los Angeles, California, 90089-1661, United States
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6
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Touj N, Mazars F, Zaragoza G, Delaude L. Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes. Beilstein J Org Chem 2023; 19:1947-1956. [PMID: 38170157 PMCID: PMC10760461 DOI: 10.3762/bjoc.19.145] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 12/12/2023] [Indexed: 01/05/2024] Open
Abstract
The synthesis of zwitterionic dithiocarboxylate adducts was achieved by deprotonating various aldiminium or 1,2,3-triazolium salts with a strong base, followed by the nucleophilic addition of the in situ-generated cyclic (alkyl)(amino) or mesoionic carbenes (CAACs or MICs) onto carbon disulfide. Nine novel compounds were isolated and fully characterized by 1H and 13C NMR, FTIR, and HRMS techniques. Moreover, the molecular structures of two CAAC·CS2 and two MIC·CS2 betaines were determined by X-ray diffraction analysis. The analytical data recorded for all these adducts were compared with those reported previously for related NHC·CS2 betaines derived from imidazolinium or (benz)imidazolium salts. Due to the absence of electronic communication between the CS2 unit and the orthogonal heterocycle, all the CAAC·CS2, MIC·CS2, and NHC·CS2 zwitterions displayed similar electronic properties and featured the same bite angle. Yet, their steric properties are liable to ample modifications by varying the exact nature of their cationic heterocycle and its substituents.
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Affiliation(s)
- Nedra Touj
- Laboratory of Catalysis, MolSys Research Unit, Université de Liège, Institut de chimie organique (B6a), Allée du six août 13, 4000 Liège, Belgium
| | - François Mazars
- Laboratory of Catalysis, MolSys Research Unit, Université de Liège, Institut de chimie organique (B6a), Allée du six août 13, 4000 Liège, Belgium
| | - Guillermo Zaragoza
- Unidad de Difracción de Rayos X, RIAIDT, Universidade de Santiago de Compostella, Edificio CACTUS, Campus Vida, 15782 Santiago de Compostela, Spain
| | - Lionel Delaude
- Laboratory of Catalysis, MolSys Research Unit, Université de Liège, Institut de chimie organique (B6a), Allée du six août 13, 4000 Liège, Belgium
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7
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Structural effect of imidazolium salts on electrochemical conversion of carbon dioxide to imidazolium carboxylate. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Schotten C, Bourne RA, Kapur N, Nguyen BN, Willans CE. Electrochemical Generation of
N
‐Heterocyclic Carbenes for Use in Synthesis and Catalysis. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202100264] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
| | - Richard A. Bourne
- School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
| | - Nikil Kapur
- School of Mechanical Engineering University of Leeds Leeds LS2 9JT UK
| | - Bao N. Nguyen
- School of Chemistry University of Leeds Leeds LS2 9JT UK
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9
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Jia M, Broderick A, Newberg JT. The Influence of Water Vapor on the Electrochemical Shift of an Ionic Liquid Measured by Ambient Pressure X-ray Photoelectron Spectroscopy. Chemphyschem 2021; 22:633-640. [PMID: 33534914 DOI: 10.1002/cphc.202001041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/02/2021] [Indexed: 11/09/2022]
Abstract
Ionic liquids (ILs) are considered to be one of the steppingstones to fabricate next generation electrochemical devices given their unique physical and chemical properties. The addition of water to ILs significantly impact electrochemical related properties including viscosity, density, conductivity, and electrochemical window. Herein we utilize ambient pressure X-ray photoelectron spectroscopy (APXPS) to examine the impact of water on values of the electrochemical shift (S), which is determined by measuring changes in binding energy shifts as a function of an external bias. APXPS spectra of C 1s, O 1s and N 1s regions are examined for the IL 1-butyl-3-methylimidazolium acetate, [C4 mim][OAc], at the IL/gas interface as a function of both water vapor pressure and external bias. Results reveal that in the absence of water vapor there is an IL ohmic drop between the working electrode and quasi reference electrode, giving rise to chemical specific S values of less than one. Upon introducing water vapor, S values approach one as a function of increasing water vapor pressure, indicating a decrease in the IL ohmic drop as the IL/water mixture becomes more conductive and the potential drop is driven by the electric double layer at the electrode/IL interface.
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Affiliation(s)
- Meng Jia
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Alicia Broderick
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Present Address: U.S. Department of Homeland Security, Science and Technology Directorate's Transportation Security Laboratory, Atlantic City, NJ, 08405, USA
| | - John T Newberg
- Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
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10
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Vetica F, Bortolami M, Petrucci R, Rocco D, Feroci M. Electrogenerated NHCs in Organic Synthesis: Ionic Liquids vs Organic Solvents Effects. CHEM REC 2021; 21:2130-2147. [PMID: 33507627 DOI: 10.1002/tcr.202000178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/08/2021] [Indexed: 12/14/2022]
Abstract
In the last twenty years, N-heterocyclic carbenes (NHCs) have been extensively studied for their application as organocatalysts in stereoselective synthesis as well as ligands for transition metals-promoted synthetic methodologies. Derived mainly from azolium salts, NHCs have demonstrated exceptional versatility in their generation usually performed by deprotonation or reduction (chemical or electrochemical). In particular, the generation of NHC under electrochemical conditions, starting from azolium-based ionic liquids, has proven to be a successful green approach and demonstrated wide applicability in organic synthesis. In this Personal Account, the application of electrogenerated NHCs in organic synthesis will be discussed, with a particular attention to the different reactivity in ionic liquids compared to classical organic solvents.
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Affiliation(s)
- Fabrizio Vetica
- Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Martina Bortolami
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Rita Petrucci
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Daniele Rocco
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Marta Feroci
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
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11
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Uzundal CB, Sahin O, Gokturk PA, Wu H, Mugele F, Ulgut B, Suzer S. X-ray Photoelectron Spectroscopy with Electrical Modulation Can Be Used to Probe Electrical Properties of Liquids and Their Interfaces at Different Stages. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16989-16999. [PMID: 31794669 DOI: 10.1021/acs.langmuir.9b03134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Operando X-ray photoelectron spectroscopy (o-XPS) has been used to record the binding energy shifts in the C 1s peak of a pristine poly(ethylene glycol) (PEG) liquid drop in an electrowetting on dielectric (EWOD) geometry and after exposing it to several high-voltage breakdown processes. This was achieved by recording XPS data while the samples were subjected to 10 V dc and ac (square-wave modulation) actuations to extract electrical information related to the liquid and its interface with the dielectric. Through analysis of the XPS data under ac actuation, a critical frequency of 170 Hz is extracted for the pristine PEG, which is translated to a resistance value of 14 MΩ for the liquid and a capacitance value of 60 pF for the dielectric, by the help of simulations using an equivalent circuit model and also by XPS analyses of a mimicking device under similar conditions. The same measurements yield an increased value of 23 MΩ for the resistance of the liquid after the breakdown by assuming that the capacitance of the dielectric stays constant. In addition, an asymmetry in polarity dependence is observed with respect to both the onset of the breakdown voltage and also the leakage behavior of the deteriorated (PEG + dielectric) system such that deviations are more pronounced at positive voltages. Both dc and ac behaviors of the postbreakdown system can also be simulated, but only by introducing an additional element, a diode or a polarity- and magnitude-dependent voltage source (VCVS), which might be attributed to negative charge accumulation at the interface. Measurements for a liquid mixture of PEG with 8% ionic liquid yields an almost 2 orders of magnitude smaller resistance for the drop as a result of the enhanced conductivity by the ions. Coupled with modeling, XPS measurements under dc and ac modulations enable probing unique electrochemical properties of liquid/solid interfaces.
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Affiliation(s)
- Can Berk Uzundal
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
| | - Ozgur Sahin
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
| | | | - Hao Wu
- Physics of Complex Fluids , University of Twente , 7522 NB , Enschede , The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids , University of Twente , 7522 NB , Enschede , The Netherlands
| | - Burak Ulgut
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
| | - Sefik Suzer
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
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12
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Jain P, Chaudhari VR, Kumar A. Water-assisted stability of carbene: cyclic voltammetric investigation of 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid. Phys Chem Chem Phys 2019; 21:24126-24131. [PMID: 31657400 DOI: 10.1039/c9cp05033g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In this work, we report electrochemical studies on imidazolium-based ionic liquids with an objective to explore the possibility of carbene formation in their dilute aqueous solutions. Conventionally, water plays a detrimental role during investigations involving ionic liquids, and this role has been investigated via electrochemical studies in aqueous ionic liquid solutions. There are varying opinions regarding the influence of water on the physicochemical behaviour of ionic liquids that require an in-depth understanding. To eludicate the role of water, we attempted to evaluate the electrochemical performance of ionic liquids in water as a solvent, and the influence of water on ionic liquids was explored through feasibility and stability studies on carbene formed in an aqueous imidazolium-based ionic liquid solution. The electrochemical investigation of an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) revealed a redox couple. Detailed investigations suggest that reduction of the imidazolium cation occurs at the C2 position, with subsequent formation of carbene. Furthermore, an anodic peak was found to be associated with the oxidation of carbene. The coulometric process associated with the anodic peaks indicated that the two-electron oxidation of carbene occurred. The stability of carbene in water was evaluated through the use of different protic and aprotic solvents. The hydrogen bond-forming ability of carbene with water seems to be responsible for its improved stability in water.
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Affiliation(s)
- Preeti Jain
- Physical & Material Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
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13
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Aydogan Gokturk P, Ulgut B, Suzer S. DC Electrowetting of Nonaqueous Liquid Revisited by XPS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7301-7308. [PMID: 29870259 DOI: 10.1021/acs.langmuir.8b01314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Liquid poly(ethylene glycol) (molecular weight, ∼600 Da) with a low vapor pressure is used as droplets in an ultrahigh-vacuum X-ray photoelectron spectrometer (XPS) chamber with traditional electrowetting on dielectric (EWOD) device geometry. We demonstrate that, using XPS data, independent of the sign of the applied voltage, the droplet expands on the substrate with the application of a nonzero voltage and contracts back when the voltage is brought back to zero. However, the main focus of the present investigation is about tracing the electrical potential developments on and around the droplet, using the shifts in the binding energy positions of the core levels representative of the liquid and/or the substrate in an noninvasive and chemically specific fashion, under imposed electrical fields, with an aim of shedding light on numerous models employed for simulating EWOD phenomenon, as well as on certain properties of liquid/solid interfaces. While the lateral resolution of XPS does not permit to interrogate the interface directly, we explicitly show that critical information can be extracted by probing both sides of the interface simultaneously under external bias in the form of potential steps or direct current. We find that, even though no potential drop is observed at the metal-wire electrode/liquid interface, the entire potential drop develops across the liquid/solid-substrate interface, which is faster than our probe time window (∼100 ms) and is promptly complying with the applied bias until breakdown. No indication of band bending nor additional broadening can be observed in the C 1s peak of the liquid, even under electrical field strengths exceeding 107 V/m. Moreover and surprisingly, the liquid recovers within seconds after each catastrophic breakdown. All of these findings are new and expected to contribute significantly to a better understanding of certain physicochemical properties of liquid/solid interfaces.
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Affiliation(s)
| | - Burak Ulgut
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
| | - Sefik Suzer
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
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