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Majumdar P, Gao R, White HS. Electroprecipitation of Nanometer-Thick Films of Ln(OH) 3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8125-8134. [PMID: 35715230 DOI: 10.1021/acs.langmuir.2c01008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We report investigations of the deposition of nanometer-thick Ln(OH)3 films (Ln = La, Ce, and Lu) and their effect on outer-sphere and inner-sphere electron-transfer reactions. Insoluble Ln(OH)3 films are deposited from aqueous solutions of LaCl3 onto the surface of 12.5 μm radius Pt microdisk electrodes during water or oxygen reduction. Both reactions produce interfacial OH-, which complexes with Ln3+, resulting in the precipitation of Ln(OH)3. Surface analyses by scanning electron microscopy (SEM), SEM-energy-dispersive X-ray spectroscopy, and atomic force microscopy indicate the formation of a 1-2 nm thick uniform film. Outer-sphere electron-transfer reactions (Ru(NH3)63+ reduction, FcMeOH oxidation, and Fe(CN)64-/3- oxidation/reduction) were investigated at Ln(OH)3-modified electrodes of different film thicknesses. The results demonstrate that the steady-state transport-limited current for these reactions decreases with an increase in the film thickness. Moreover, the degree of blockage depends upon the redox species, suggesting that the Ln(OH)3 films are free from pinholes greater than the size of the redox molecules. This suggests that the films are either ionically conducting or that electron tunneling occurs across these thin layers. A similar blocking effect was observed for the inner-sphere reductions of H2O and O2. We further demonstrate that the thickness of La(OH)3 films can be controlled by anodic dissolution. Additionally, we show that La3+ lowers the supersaturation of dissolved H2 required to nucleate a stable nanobubble.
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Affiliation(s)
- Pavel Majumdar
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Rui Gao
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Henry S White
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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2
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Kurapati N, Pathirathna P, Ziegler CJ, Amemiya S. Adsorption and Electron‐Transfer Mechanisms of Ferrocene Carboxylates and Sulfonates at Highly Oriented Pyrolytic Graphite. ChemElectroChem 2019. [DOI: 10.1002/celc.201901664] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Niraja Kurapati
- Department of Chemistry University of Pittsburgh Pittsburgh, PA 15260 USA
| | | | | | - Shigeru Amemiya
- Department of Chemistry University of Pittsburgh Pittsburgh, PA 15260 USA
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3
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Meng Y, Du M, Cao F. Influence of chloride ion adsorption on the kinetics and mechanism of Ru(NH3)63+/2+ electrode reactions. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.134863] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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4
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Al-Kutubi H, Voci S, Rassaei L, Sojic N, Mathwig K. Enhanced annihilation electrochemiluminescence by nanofluidic confinement. Chem Sci 2018; 9:8946-8950. [PMID: 30647886 PMCID: PMC6301198 DOI: 10.1039/c8sc03209b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/30/2018] [Indexed: 12/30/2022] Open
Abstract
The generation of stable enhanced light emission by electrochemiluminescence in microfabricated nanofluidic electrochemical devices is demonstrated for the first time by exploiting nanogap amplification.
Microfabricated nanofluidic electrochemical devices offer a highly controlled nanochannel geometry; they confine the volume of chemical reactions to the nanoscale and enable greatly amplified electrochemical detection. Here, the generation of stable light emission by electrochemiluminescence (ECL) in transparent nanofluidic devices is demonstrated for the first time by exploiting nanogap amplification. Through continuous oxidation and reduction of [Ru(bpy)3]2+ luminophores at electrodes positioned at opposite walls of a 100 nm nanochannel, we compare classic redox cycling and ECL annihilation. Enhanced ECL light emission of attomole luminophore quantities is evidenced under ambient conditions due to the spatial confinement in a 10 femtoliter volume, resulting in a short diffusion timescale and highly efficient ECL reaction pathways at the nanoscale.
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Affiliation(s)
- Hanan Al-Kutubi
- University of Groningen , Groningen Research Institute of Pharmacy , Pharmaceutical Analysis , P.O. Box 196 , 9700 AD Groningen , The Netherlands .
| | - Silvia Voci
- University of Bordeaux , Bordeaux INP , Institut des Sciences Moléculaires , UMR CNRS 5255 , 33607 Pessac , France .
| | - Liza Rassaei
- Rotterdam School of Management , Erasmus University , Burgemeester Oudlaan 50 , 3062 PA Rotterdam , The Netherlands.,Delft University of Technology , Van der Maasweg 9 , 2629 HZ Delft , The Netherlands
| | - Neso Sojic
- University of Bordeaux , Bordeaux INP , Institut des Sciences Moléculaires , UMR CNRS 5255 , 33607 Pessac , France .
| | - Klaus Mathwig
- University of Groningen , Groningen Research Institute of Pharmacy , Pharmaceutical Analysis , P.O. Box 196 , 9700 AD Groningen , The Netherlands .
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5
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Double layer effects in voltammetric measurements with scanning electrochemical microscopy (SECM). J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2017.10.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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6
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Burgess M, Hernández-Burgos K, Schuh JK, Davila J, Montoto EC, Ewoldt RH, Rodríguez-López J. Modulation of the Electrochemical Reactivity of Solubilized Redox Active Polymers via Polyelectrolyte Dynamics. J Am Chem Soc 2018; 140:2093-2104. [PMID: 29369622 DOI: 10.1021/jacs.7b08353] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Redox active polymers (RAPs) are electrochemically versatile materials that find key applications in energy storage, sensing, and surface modification. In spite of the ubiquity of RAP-modified electrodes, a critical knowledge gap exists in the understanding of the electrochemistry of soluble RAPs and their relation to polyelectrolyte dynamics. Here, we explore for the first time the intersection between polyelectrolyte behavior and the electrochemical response that highly soluble and highly substituted RAPs with viologen, ferrocene, and nitrostyrene moieties elicit at electrodes. This comprehensive study of RAP electrolytes over several orders of magnitude in concentration and ionic strength reveals distinct signatures consistent with surface confined, colloidal, and bulk-like electrochemical behavior. These differences emerge across polyelectrolyte packing regimes and are strongly modulated by changes in RAP coil size and electrostatic interactions with the electrode. We found that, unlike monomer motifs, simple changes in the ionic strength caused variations over 1 order of magnitude in the current measured at the electrode. In addition, the thermodynamics of adsorbed RAP films were also affected, giving rise to standard reduction potential shifts leading to redox kinetic effects as a result of the mediating nature of the RAP film in equilibrium with the solution. Full electrochemical characterization via transient and steady-state techniques, including the use of ultramicroelectrodes and the rotating disk electrode, were correlated to dynamic light scattering, ellipsometry, and viscometric analysis. These methods helped elucidate the relationship between electrochemical behavior and RAP coil size, film thickness, and polyelectrolyte packing regime. This study underscores the role of electrostatics in modulating the reactivity of redox polyelectrolytes.
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Affiliation(s)
- Mark Burgess
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | | | - Jonathon K Schuh
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | | | - Elena C Montoto
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | - Randy H Ewoldt
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
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7
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Perera RT, Rosenstein JK. Quasi-reference electrodes in confined electrochemical cells can result in in situ production of metallic nanoparticles. Sci Rep 2018; 8:1965. [PMID: 29386652 PMCID: PMC5792608 DOI: 10.1038/s41598-018-20412-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/15/2018] [Indexed: 12/16/2022] Open
Abstract
Nanoscale working electrodes and miniaturized electroanalytical devices are valuable platforms to probe molecular phenomena and perform chemical analyses. However, the inherent close distance of metallic electrodes integrated into a small volume of electrolyte can complicate classical electroanalytical techniques. In this study, we use a scanning nanopipette contact probe as a model miniaturized electrochemical cell to demonstrate measurable side effects of the reaction occurring at a quasi-reference electrode. We provide evidence for in situ generation of nanoparticles in the absence of any electroactive species and we critically analyze the origin, nucleation, dissolution and dynamic behavior of these nanoparticles as they appear at the working electrode. It is crucial to recognize the implications of using quasi-reference electrodes in confined electrochemical cells, in order to accurately interpret the results of nanoscale electrochemical experiments.
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Affiliation(s)
- Rukshan T Perera
- School of Engineering, Brown University, 184 Hope Street, Providence, RI, 02912, USA
| | - Jacob K Rosenstein
- School of Engineering, Brown University, 184 Hope Street, Providence, RI, 02912, USA.
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8
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Kostiuchenko ZA, Glazer PJ, Mendes E, Lemay SG. Chemical physics of electroactive materials - the oft-overlooked faces of electrochemistry. Faraday Discuss 2017; 199:9-28. [PMID: 28654123 DOI: 10.1039/c7fd00117g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Electroactive materials and their applications are enjoying renewed attention, in no small part motivated by the advent of nanoscale tools for their preparation and study. While the fundamentals of charge and mass transport in electrolytes on this scale are by and large well understood, their interplay can have subtle manifestations in the more complex situations typical of, for example, integrated microfluidics-based applications. In particular, the role of faradaic processes is often overlooked or, at best, purposefully suppressed via experimental design. In this introductory article we discuss, using simple illustrations from our laboratories, some of the manifestations of electrochemistry in electroactive materials.
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Affiliation(s)
- Zinaida A Kostiuchenko
- MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
| | - Piotr J Glazer
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Eduardo Mendes
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Serge G Lemay
- MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
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9
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Zafarani HR, Mathwig K, Sudhölter EJR, Rassaei L. Electrochemical Amplification in Side-by-Side Attoliter Nanogap Transducers. ACS Sens 2017; 2:724-728. [PMID: 28670622 PMCID: PMC5485373 DOI: 10.1021/acssensors.7b00180] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/16/2017] [Indexed: 11/30/2022]
Abstract
We report a strategy for the fabrication of a new type of electrochemical nanogap transducer. These nanogap devices are based on signal amplification by redox cycling. Using two steps of electron-beam lithography, vertical gold electrodes are fabricated side by side at a 70 nm distance encompassing a 20 attoliter open nanogap volume. We demonstrate a current amplification factor of 2.5 as well as the possibility to detect the signal of only 60 analyte molecules occupying the detection volume. Experimental voltammetry results are compared to calculations from finite element analysis.
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Affiliation(s)
- Hamid Reza Zafarani
- Laboratory of Organic
Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Klaus Mathwig
- University of Groningen, Groningen Research Institute of Pharmacy, Pharmaceutical Analysis, P.O. Box 196, 9700 AD Groningen, The Netherlands
| | - Ernst J. R. Sudhölter
- Laboratory of Organic
Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Liza Rassaei
- Laboratory of Organic
Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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10
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Bae JH, Yu Y, Mirkin MV. Diffuse Layer Effect on Electron-Transfer Kinetics Measured by Scanning Electrochemical Microscopy (SECM). J Phys Chem Lett 2017; 8:1338-1342. [PMID: 28286950 DOI: 10.1021/acs.jpclett.7b00161] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent theoretical and experimental studies revealed strong effects of the electrical double layer (EDL) on mass transfer at nanometer-sized electrodes and in electrochemical nanogaps. Although the EDL effect is much stronger in weakly supported media, it can significantly influence the kinetics of electron-transfer processes involving multicharged ionic redox species, even at high concentrations of supporting electrolyte. We measured the kinetics of Fe(CN)64- oxidation in 1 M KCl solution at the Pt nanoelectrode used as a tip in the scanning electrochemical microscope. The apparent standard rate constant values extracted from tip voltammograms without double-layer correction increased markedly with the decreasing separation distance between the tip and substrate electrodes. The same steady-state voltammograms were fitted to the theory including the EDL effect and yielded the rate constant essentially independent of the separation distance.
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Affiliation(s)
- Je Hyun Bae
- Department of Chemistry and Biochemistry, Queens College , Flushing, New York 11367, United States
| | - Yun Yu
- Department of Chemistry and Biochemistry, Queens College , Flushing, New York 11367, United States
- The Graduate Center of CUNY , New York, New York 10016, United States
| | - Michael V Mirkin
- Department of Chemistry and Biochemistry, Queens College , Flushing, New York 11367, United States
- The Graduate Center of CUNY , New York, New York 10016, United States
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11
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Zafarani HR, Mathwig K, Lemay SG, Sudhölter EJR, Rassaei L. Modulating Selectivity in Nanogap Sensors. ACS Sens 2016. [DOI: 10.1021/acssensors.6b00556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hamid Reza Zafarani
- Laboratory
of Organic Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Klaus Mathwig
- Pharmaceutical
Analysis, Groningen Research Institute of Pharmacy, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands
| | - Serge G. Lemay
- MESA+
Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Ernst J. R. Sudhölter
- Laboratory
of Organic Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Liza Rassaei
- Laboratory
of Organic Materials and Interfaces, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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12
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Cuharuc AS, Zhang G, Unwin PR. Electrochemistry of ferrocene derivatives on highly oriented pyrolytic graphite (HOPG): quantification and impacts of surface adsorption. Phys Chem Chem Phys 2016; 18:4966-77. [PMID: 26812483 DOI: 10.1039/c5cp06325f] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cyclic voltammetry of three ferrocene derivatives - (ferrocenylmethyl)trimethylammonium (FcTMA(+)), ferrocenecarboxylic acid (FcCOOH), and ferrocenemethanol (FcCH2OH) - in aqueous solutions shows that the reduced form of the first two redox species weakly adsorbs onto freshly cleaved surfaces of highly oriented pyrolytic graphite (HOPG), with the fractional surface coverage being in excess of 10% of a monolayer at a bulk concentration level of 0.25 mM for both compounds. FcCH2OH was found to exhibit greater and stronger adsorption (up to a monolayer) for the same bulk concentration. The adsorption of FcTMA(+) on freshly cleaved surfaces of high quality (low step edge density) and low quality (high step edge density) HOPG is the same within experimental error, suggesting that the amount of step edges has no influence on the adsorption process. The amount of adsorption of FcTMA(+) is the same (within error) for low quality HOPG, irrespective of whether the surface is freshly cleaved or left in air for up to 12 hours, while - with aging - high quality HOPG adsorbs notably more FcTMA(+). The formation of an airborne contaminating film is proposed to be responsible for the enhanced entrapment of FcTMA(+) on aged high quality HOPG surfaces, while low quality surfaces appear less prone to the accumulation of such films. The impact of the adsorption of ferrocene derivatives on graphite for voltammetric studies is discussed. Adsorption is quantified by developing a theory and methodology to process cyclic voltammetry data from peak current measurements. The accuracy and applicability, as well as limits of the approach, are demonstrated for various adsorption isotherms.
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Affiliation(s)
| | - Guohui Zhang
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Patrick R Unwin
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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13
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Ostojic N, Thorpe JH, Crooks RM. Electron Transfer Facilitated by Dendrimer-Encapsulated Pt Nanoparticles Across Ultrathin, Insulating Oxide Films. J Am Chem Soc 2016; 138:6829-37. [DOI: 10.1021/jacs.6b03149] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Nevena Ostojic
- Department of Chemistry,
Center for Electrochemistry, and the Center for Nano- and Molecular
Science and Technology, The University of Texas at Austin, 105
E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - James H. Thorpe
- Department of Chemistry,
Center for Electrochemistry, and the Center for Nano- and Molecular
Science and Technology, The University of Texas at Austin, 105
E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Richard M. Crooks
- Department of Chemistry,
Center for Electrochemistry, and the Center for Nano- and Molecular
Science and Technology, The University of Texas at Austin, 105
E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
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14
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Tan SY, Zhang J, Bond AM, Macpherson JV, Unwin PR. Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements. Anal Chem 2016; 88:3272-80. [PMID: 26877069 DOI: 10.1021/acs.analchem.5b04715] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Sze-yin Tan
- Department
of Chemistry, University of Warwick, Coventry, West Midlands CV4 7AL, United Kingdom
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Jie Zhang
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Alan M. Bond
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Julie V. Macpherson
- Department
of Chemistry, University of Warwick, Coventry, West Midlands CV4 7AL, United Kingdom
| | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry, West Midlands CV4 7AL, United Kingdom
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15
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The impact of nonelectrostatic physisorption of ions on free energies and forces between redox electrodes: ion-specific repulsive peaks. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2015.12.090] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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16
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Affiliation(s)
- Stephen M. Oja
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Yunshan Fan
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Chadd M. Armstrong
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Peter Defnet
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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17
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Byers JC, Paulose Nadappuram B, Perry D, McKelvey K, Colburn AW, Unwin PR. Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids. Anal Chem 2015; 87:10450-6. [DOI: 10.1021/acs.analchem.5b02569] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Joshua C. Byers
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | | | - David Perry
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Kim McKelvey
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Alex W. Colburn
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Patrick R. Unwin
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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18
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Velický M, Bissett MA, Toth PS, Patten HV, Worrall SD, Rodgers ANJ, Hill EW, Kinloch IA, Novoselov KS, Georgiou T, Britnell L, Dryfe RAW. Electron transfer kinetics on natural crystals of MoS2 and graphite. Phys Chem Chem Phys 2015; 17:17844-53. [PMID: 26088339 DOI: 10.1039/c5cp02490k] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Here, we evaluate the electrochemical performance of sparsely studied natural crystals of molybdenite and graphite, which have increasingly been used for fabrication of next generation monolayer molybdenum disulphide and graphene energy storage devices. Heterogeneous electron transfer kinetics of several redox mediators, including Fe(CN)6(3-/4-), Ru(NH3)6(3+/2+) and IrCl6(2-/3-) are determined using voltammetry in a micro-droplet cell. The kinetics on both materials are studied as a function of surface defectiveness, surface ageing, applied potential and illumination. We find that the basal planes of both natural MoS2 and graphite show significant electroactivity, but a large decrease in electron transfer kinetics is observed on atmosphere-aged surfaces in comparison to in situ freshly cleaved surfaces of both materials. This is attributed to surface oxidation and adsorption of airborne contaminants at the surface exposed to an ambient environment. In contrast to semimetallic graphite, the electrode kinetics on semiconducting MoS2 are strongly dependent on the surface illumination and applied potential. Furthermore, while visibly present defects/cracks do not significantly affect the response of graphite, the kinetics on MoS2 systematically accelerate with small increase in disorder. These findings have direct implications for use of MoS2 and graphene/graphite as electrode materials in electrochemistry-related applications.
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Affiliation(s)
- Matěj Velický
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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19
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Mathwig K, Albrecht T, Goluch ED, Rassaei L. Challenges of Biomolecular Detection at the Nanoscale: Nanopores and Microelectrodes. Anal Chem 2015; 87:5470-5. [DOI: 10.1021/acs.analchem.5b01167] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Klaus Mathwig
- Pharmaceutical
Analysis, Groningen Research Institute of Pharmacy, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands
| | - Tim Albrecht
- Department
of Chemistry, Imperial College London, Exhibition Road, South Kensington
Campus, London, SW7 2AZ, U.K
| | - Edgar D. Goluch
- Department
of Chemical Engineering, Northeastern University, 360 Huntington Avenue, 313SN, Boston, Massachusetts 02115, United States
| | - Liza Rassaei
- Department
of Chemical Engineering, Delft University of Technology, Julianalaan
136, 2628 BL Delft, The Netherlands
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20
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Feldberg SW, Edwards MA. Current response for a single redox moiety trapped in a closed generator-collector system: the role of capacitive coupling. Anal Chem 2015; 87:3778-83. [PMID: 25738594 DOI: 10.1021/ac504375j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A theoretical model is proposed to describe the steady-state average limiting current associated with a single redox moiety (ox or red) trapped in a closed generator-collector system along with excess supporting electrolyte. By "closed" we mean that neither solvent nor solutes can enter or leave the system. The potential difference, EOE - ERE, between the oxidizing electrode (OE) and the reducing electrode (RE) is maintained constant with the values of EOE and ERE chosen so that the operative faradaic electrode processes are very fast, i.e., red = ox + nETe(-) (kox = ∞) at the OE and ox + nETe(-) = red (kred = ∞) at the RE. Because there is only a single redox moiety the faradaic process occurs at only one electrode at a time while current at the other electrode is purely capacitive (we refer to this as capacitive coupling). We propose that a two-step process is required to transfer nETqe coulombs (qe is the absolute value of the elemental electronic charge). The first step is associated with diffusion (approximated as a random walk) of a single red moiety to the OE where it is oxidized to ox with a concomitant transfer of qstep1 (= nETqe/(1 + AOECOE/ARECRE)) coulombs; the second step is associated with the diffusion (random walk) of the newly formed single ox moiety to the RE with the concomitant transfer of qstep2 (= nETqe/(1 + ARECRE/AOECOE)) coulombs (ARE,AOE andCRE,COEare the areas (cm(2)) and differential capacitances (farads cm(-2)) of the corresponding electrodes). The total charge transferred in the two steps is nETqe(= qstep1 + qstep2). Transport of the redox moiety from one electrode to the other is accomplished by a random walk. The probability density function (pdf) and cumulative density function (CDF) for the duration of a full redox cycle are presented as the analytical solution to a 1-dimensional bounded random-walk problem (confirmed by numerical simulation). These show that tfull, the average time for the full redox cycle (step 1 + step 2), is equal to L(2)/D where L is the intraelectrode distance and D is the diffusion coefficient. The average steady-state limiting current is shown to be described by the familiar expression for a generator-collector system: ilim = (qstep1 + qstep2)/tfull = nETqe/tfull = nETqeD/L(2).
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Affiliation(s)
- Stephen W Feldberg
- †Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Martin A Edwards
- ‡Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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Kätelhön E, Krause KJ, Mathwig K, Lemay SG, Wolfrum B. Noise phenomena caused by reversible adsorption in nanoscale electrochemical devices. ACS NANO 2014; 8:4924-4930. [PMID: 24694343 DOI: 10.1021/nn500941g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We theoretically investigate reversible adsorption in electrochemical devices on a molecular level. To this end, a computational framework is introduced, which is based on 3D random walks including probabilities for adsorption and desorption events at surfaces. We demonstrate that this approach can be used to investigate adsorption phenomena in electrochemical sensors by analyzing experimental noise spectra of a nanofluidic redox cycling device. The evaluation of simulated and experimental results reveals an upper limit for the average adsorption time of ferrocene dimethanol of ∼200 μs. We apply our model to predict current noise spectra of further electrochemical experiments based on interdigitated arrays and scanning electrochemical microscopy. Since the spectra strongly depend on the molecular adsorption characteristics of the detected analyte, we can suggest key indicators of adsorption phenomena in noise spectroscopy depending on the geometric aspect of the experimental setup.
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Affiliation(s)
- Enno Kätelhön
- Institute of Bioelectronics (PGI-8/ICS-8) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich , 52425 Jülich, Germany
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