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52
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Ortiz-Ledón CA, Zoski CG. Fabrication of Glass-Insulated Ultramicrometer to Submicrometer Carbon Fiber Electrodes to Support a Single Nanoparticle and Nanoparticle Ensembles in Electrocatalytic Investigations. Anal Chem 2018; 90:12616-12624. [DOI: 10.1021/acs.analchem.8b02785] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- César A. Ortiz-Ledón
- Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Cynthia G. Zoski
- Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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53
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Macedo LJA, Iost RM, Hassan A, Balasubramanian K, Crespilho FN. Bioelectronics and Interfaces Using Monolayer Graphene. ChemElectroChem 2018. [DOI: 10.1002/celc.201800934] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Lucyano J. A. Macedo
- São Carlos Institute of Chemistry; University of São Paulo; São Carlos SP 13560-970 Brazil
| | - Rodrigo M. Iost
- Department of Chemistry School of Analytical Sciences Adlershof (SALSA) and IRIS Adlershof; Humboldt-Universität zu Berlin; Berlin 10099 Germany
| | - Ayaz Hassan
- São Carlos Institute of Chemistry; University of São Paulo; São Carlos SP 13560-970 Brazil
| | - Kannan Balasubramanian
- Department of Chemistry School of Analytical Sciences Adlershof (SALSA) and IRIS Adlershof; Humboldt-Universität zu Berlin; Berlin 10099 Germany
| | - Frank N. Crespilho
- São Carlos Institute of Chemistry; University of São Paulo; São Carlos SP 13560-970 Brazil
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54
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Ruggeri FS, Charmet J, Kartanas T, Peter Q, Chia S, Habchi J, Dobson CM, Vendruscolo M, Knowles TPJ. Microfluidic deposition for resolving single-molecule protein architecture and heterogeneity. Nat Commun 2018; 9:3890. [PMID: 30250131 PMCID: PMC6155325 DOI: 10.1038/s41467-018-06345-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 07/31/2018] [Indexed: 11/10/2022] Open
Abstract
Scanning probe microscopy provides a unique window into the morphology, mechanics, and structure of proteins and their complexes on the nanoscale. Such measurements require, however, deposition of samples onto substrates. This process can affect conformations and assembly states of the molecular species under investigation and can bias the molecular populations observed in heterogeneous samples through differential adsorption. Here, we show that these limitations can be overcome with a single-step microfluidic spray deposition platform. This method transfers biological solutions to substrates as microdroplets with subpicoliter volume, drying in milliseconds, a timescale that is shorter than typical diffusion times of proteins on liquid–solid interfaces, thus avoiding surface mass transport and change to the assembly state. Finally, the single-step deposition ensures the attachment of the full molecular content of the sample to the substrate, allowing quantitative measurements of different molecular populations within heterogeneous systems, including protein aggregates. Manual sample deposition on a substrate can introduce artifacts in quantitative AFM measurements. Here the authors present a microfluidic spray device for reliable deposition of subpicoliter droplets which dry out in milliseconds after landing on the surface, thereby avoiding protein self-assembly.
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Affiliation(s)
| | - Jerome Charmet
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.,WMG, University of Warwick, Coventry, CV4 7AL, UK
| | - Tadas Kartanas
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Quentin Peter
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Sean Chia
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Johnny Habchi
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Christopher M Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Michele Vendruscolo
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. .,Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
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55
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Nayak P, Jiang Q, Mohanraman R, Anjum D, Hedhili MN, Alshareef HN. Inherent electrochemistry and charge transfer properties of few-layered two-dimensional Ti 3C 2T x MXene. NANOSCALE 2018; 10:17030-17037. [PMID: 29926864 DOI: 10.1039/c8nr01883a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the effect of the Ti3C2Tx MXene flake thickness on its inherent electrochemistry and heterogeneous charge transfer characteristics. It is shown that Ti3C2Tx undergoes irreversible oxidation in a positive potential window, which strongly depends on the flake thickness and pH of the electrolyte. Few-layered Ti3C2Tx exhibits faster electron transfer kinetics (k0 = 0.09533 cm s-1) with a [Fe(CN)6]4-/3- redox mediator compared to multi-layered Ti3C2Tx (k0 = 0.00503 cm s-1). In addition, the few-layered free standing Ti3C2Tx film electrode remains intact after enduring irreversible oxidation.
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Affiliation(s)
- Pranati Nayak
- Materials Science and Engineering, Physical Sciences & Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
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56
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O’Neil GD, Kuo HW, Lomax DN, Wright J, Esposito DV. Scanning Line Probe Microscopy: Beyond the Point Probe. Anal Chem 2018; 90:11531-11537. [DOI: 10.1021/acs.analchem.8b02852] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Glen D. O’Neil
- Department of Chemical Engineering, Columbia University in the City of New York, New York, New York 10027, United States
| | - Han-wen Kuo
- Department of Electrical Engineering, Data Science Institute, Columbia University in the City of New York, New York, New York 10027, United States
| | - Duncan N. Lomax
- Department of Chemical Engineering, Columbia University in the City of New York, New York, New York 10027, United States
| | - John Wright
- Department of Electrical Engineering, Data Science Institute, Columbia University in the City of New York, New York, New York 10027, United States
| | - Daniel V. Esposito
- Department of Chemical Engineering, Columbia University in the City of New York, New York, New York 10027, United States
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57
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Sugime H, Ushiyama T, Nishimura K, Ohno Y, Noda S. An interdigitated electrode with dense carbon nanotube forests on conductive supports for electrochemical biosensors. Analyst 2018; 143:3635-3642. [PMID: 29956699 DOI: 10.1039/c8an00528a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A highly sensitive interdigitated electrode (IDE) with vertically aligned dense carbon nanotube forests directly grown on conductive supports was demonstrated by combining UV lithography and a low temperature chemical vapor deposition process (470 °C). The cyclic voltammetry (CV) measurements of K4[Fe(CN)6] showed that the redox current of the IDE with CNT forests (CNTF-IDE) reached the steady state much more quickly compared to that of conventional gold IDE (Au-IDE). The performance of the CNTF-IDE largely depended on the geometry of the electrodes (e.g. width and gap). With the optimum three-dimensional electrode structure, the anodic current was amplified by a factor of ∼18 and ∼67 in the CV and the chronoamperometry measurements, respectively. The collection efficiency, defined as the ratio of the cathodic current to the anodic current at steady state, was improved up to 97.3%. The selective detection of dopamine (DA) under the coexistence of l-ascorbic acid with high concentration (100 μM) was achieved with a linear range of 100 nM-100 μM, a sensitivity of 14.3 mA mol-1 L, and a limit of detection (LOD, S/N = 3) of 42 nM. Compared to the conventional carbon electrodes, the CNTF-IDE showed superior anti-fouling property, which is of significant importance for practical applications, with a negligible shift of the half-wave potential (ΔE1/2 < 1.4 mV) for repeated CV measurements of DA at high concentration (100 μM).
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Affiliation(s)
- Hisashi Sugime
- Waseda Institute for Advanced Study, Waseda University, 1-6-1 Nishi Waseda, Shijuku-ku, Tokyo 169-8050, Japan.
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58
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Álvarez-Martos I, Ferapontova EE. Electrocatalytic Discrimination between Dopamine and Norepinephrine at Graphite and Basal Plane HOPG Electrodes. ELECTROANAL 2018. [DOI: 10.1002/elan.201700837] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Isabel Álvarez-Martos
- Interdisciplinary Nanoscience Center (iNANO); Aarhus University; Gustav Wieds Vej 14 DK-8000 Aarhus C Denmark
| | - Elena E. Ferapontova
- Interdisciplinary Nanoscience Center (iNANO); Aarhus University; Gustav Wieds Vej 14 DK-8000 Aarhus C Denmark
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60
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Kolagatla S, Subramanian P, Schechter A. Nanoscale mapping of catalytic hotspots on Fe, N-modified HOPG by scanning electrochemical microscopy-atomic force microscopy. NANOSCALE 2018; 10:6962-6970. [PMID: 29610805 DOI: 10.1039/c8nr00849c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The scanning electrochemical microscopy-atomic force microscopy (SECM-AFM) technique is used to map catalytic currents post Fe and N surface modification of graphitic carbon with an ultra-high resolution of 50 nm. The oxidation current of the partial reduction product, hydrogen peroxide, was also mapped in the same location in the graphitic carbon. The current mapping and ex situ spectroscopic evidence revealed that Fe-coordinated nitrogen sites formed both in the edge and basal planes of highly ordered pyrolytic graphite (HOPG) constitute the primary oxygen reduction catalytic sites in acid solutions of this important yet insufficiently understood class of catalysts.
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61
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Lehmann K, Yurchenko O, Melke J, Fischer A, Urban G. High electrocatalytic activity of metal-free and non-doped hierarchical carbon nanowalls towards oxygen reduction reaction. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.03.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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62
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Quantum and electrochemical interplays in hydrogenated graphene. Nat Commun 2018; 9:793. [PMID: 29476098 PMCID: PMC5824792 DOI: 10.1038/s41467-018-03026-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 01/15/2018] [Indexed: 11/16/2022] Open
Abstract
The design of electrochemically gated graphene field-effect transistors for detecting charged species in real time, greatly depends on our ability to understand and maintain a low level of electrochemical current. Here, we exploit the interplay between the electrical in-plane transport and the electrochemical activity of graphene. We found that the addition of one H-sp3 defect per hundred thousand carbon atoms reduces the electron transfer rate of the graphene basal plane by more than five times while preserving its excellent carrier mobility. Remarkably, the quantum capacitance provides insight into the changes of the electronic structure of graphene upon hydrogenation, which predicts well the suppression of the electrochemical activity based on the non-adiabatic theory of electron transfer. Thus, our work unravels the interplay between the quantum transport and electrochemical kinetics of graphene and suggests hydrogenated graphene as a potent material for sensing applications with performances going beyond previously reported graphene transistor-based sensors. Electrochemically-gated graphene field-effect transistors show promise for sensing of charged species in real time. Here, the authors leverage the interplay between electrical in-plane transport and electrochemical activity to explore the sensing performance of hydrogenated graphene.
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63
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Kislenko SA. Effect of high donor number solvent and cathode morphology on interfacial processes in Li-air batteries. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1742-6596/946/1/012029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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64
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Stern LA, Mocny P, Vrubel H, Bilgic T, Klok HA, Hu X. Polymer-Brush-Templated Three-Dimensional Molybdenum Sulfide Catalyst for Hydrogen Evolution. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6253-6261. [PMID: 29369614 DOI: 10.1021/acsami.7b16679] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Earth-abundant hydrogen evolution catalysts are essential for high-efficiency solar-driven water splitting. Although a significant amount of studies have been dedicated to the development of new catalytic materials, the microscopic assembly of these materials has not been widely investigated. Here, we describe an approach to control the three-dimensional (3D) assembly of amorphous molybdenum sulfide using polymer brushes as a template. To this end, poly(dimethylaminoethyl methacrylate) brushes were grown from highly oriented pyrolytic graphite. These cationic polymer films bind anionic MoS42- through an anion-exchange reaction. In a final oxidation step, the polymer-bound MoS42- is converted into the amorphous MoSx catalyst. The flexibility of the assembly design allowed systematic optimization of the 3D catalyst. The best system exhibited turnover frequencies up to 1.3 and 4.9 s-1 at overpotentials of 200 and 250 mV, respectively. This turnover frequency stands out among various molybdenum sulfide catalysts. The work demonstrates a novel strategy to control the assembly of hydrogen evolution reaction catalysts.
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Affiliation(s)
- Lucas-Alexandre Stern
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI , BCH 3305, 1015 Lausanne, Switzerland
| | - Piotr Mocny
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL) , Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland
| | - Heron Vrubel
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI , BCH 3305, 1015 Lausanne, Switzerland
| | - Tugba Bilgic
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL) , Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland
| | - Harm-Anton Klok
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL) , Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI , BCH 3305, 1015 Lausanne, Switzerland
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65
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Martín-Yerga D, Costa-García A. Stabilization of electrogenerated copper species on electrodes modified with quantum dots. Phys Chem Chem Phys 2018; 19:5018-5027. [PMID: 28165091 DOI: 10.1039/c6cp07957a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Quantum dots (QDs) have special optical, surface, and electronic properties that make them useful for electrochemical applications. In this work, the electrochemical behavior of copper in ammonia medium is described using bare screen-printed carbon electrodes and the same modified with CdSe/ZnS QDs. At the bare electrodes, the electrogenerated Cu(i) and Cu(0) species are oxidized by dissolved oxygen in a fast coupled chemical reaction, while at the QDs-modified electrode, the re-oxidation of Cu(i) and Cu(0) species can be observed, which indicates that they are stabilized by the nanocrystals present on the electrode surface. A weak adsorption is proposed as the main cause for this stabilization. The electrodeposition on electrodes modified with QDs allows the generation of random nanostructures with copper nanoparticles, avoiding the preferential nucleation onto the most active electrode areas.
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Affiliation(s)
- Daniel Martín-Yerga
- Departamento de Química Física y Analítica, Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
| | - Agustín Costa-García
- Departamento de Química Física y Analítica, Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
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66
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Meyler RE, Edwards MA, Macpherson JV. Exploring the suitability of different electrode materials for hypochlorite quantification at high concentration in alkaline solutions. Electrochem commun 2018. [DOI: 10.1016/j.elecom.2017.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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67
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Rüdiger C, Valero-Vidal C, Favaro M, Agnoli S, Granozzi G, Kunze-Liebhäuser J. Effect of Air-Aging on the Electrochemical Characteristics of TiO
x
C
y
Films for Electrocatalysis Applications. ChemElectroChem 2017. [DOI: 10.1002/celc.201700912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Celine Rüdiger
- Physik-Department; Technische Universität München; James-Franck-Str. 1 85748 Garching Germany
| | - Carlos Valero-Vidal
- Physik-Department; Technische Universität München; James-Franck-Str. 1 85748 Garching Germany
- Institut für Physikalische Chemie; Leopold-Franzens-Universität Innsbruck; Innrain 52c 6020 Innsbruck Austria
- Advanced Light Source (ALS) and; Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory; 1 Cyclotron Road Berkeley CA 94720 United States
| | - Marco Favaro
- Dipartimento di Scienze Chimiche; Università di Padova Via Marzolo 1 35131 Padova Italy
- Helmholtz-Zentrum Berlin (HZB); Institute for Solar Fuels; Hahn-Meitner-Platz 1 14109 Berlin Germany
| | - Stefano Agnoli
- Dipartimento di Scienze Chimiche; Università di Padova Via Marzolo 1 35131 Padova Italy
| | - Gaetano Granozzi
- Dipartimento di Scienze Chimiche; Università di Padova Via Marzolo 1 35131 Padova Italy
| | - Julia Kunze-Liebhäuser
- Institut für Physikalische Chemie; Leopold-Franzens-Universität Innsbruck; Innrain 52c 6020 Innsbruck Austria
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68
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Parker JF, Kamm GE, McGovern AD, DeSario PA, Rolison DR, Lytle JC, Long JW. Rewriting Electron-Transfer Kinetics at Pyrolytic Carbon Electrodes Decorated with Nanometric Ruthenium Oxide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:9416-9425. [PMID: 28617602 DOI: 10.1021/acs.langmuir.7b01107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Platinum is state-of-the-art for fast electron transfer whereas carbon electrodes, which have semimetal electronic character, typically exhibit slow electron-transfer kinetics. But when we turn to practical electrochemical devices, we turn to carbon. To move energy devices and electro(bio)analytical measurements to a new performance curve requires improved electron-transfer rates at carbon. We approach this challenge with electroless deposition of disordered, nanoscopic anhydrous ruthenium oxide at pyrolytic carbon prepared by thermal decomposition of benzene (RuOx@CVD-C). We assessed traditionally fast, chloride-assisted ([Fe(CN)6]3-/4-) and notoriously slow ([Fe(H2O)6]3+/2+) electron-transfer redox probes at CVD-C and RuOx@CVD-C electrodes and calculated standard heterogeneous rate constants as a function of heat treatment to crystallize the disordered RuOx domains to their rutile form. For the fast electron-transfer probe, [Fe(CN)6]3-/4-, the rate increases by 34× over CVD-C once the RuOx is calcined to form crystalline rutile RuO2. For the classically outer-sphere [Fe(H2O)6]3+/2+, electron-transfer rates increase by an even greater degree over CVD-C (55×). The standard heterogeneous rate constant for each probe approaches that observed at Pt but does so using only minimal loadings of RuOx.
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Affiliation(s)
- Joseph F Parker
- Surface Chemistry Branch, Code 6170, U.S. Naval Research Laboratory, Washington, DC 20375, United States
| | - Gabrielle E Kamm
- Chemistry Department, Pacific Lutheran University , Tacoma, Washington 98447, United States
| | - Ashlee D McGovern
- Chemistry Department, Pacific Lutheran University , Tacoma, Washington 98447, United States
| | - Paul A DeSario
- Surface Chemistry Branch, Code 6170, U.S. Naval Research Laboratory, Washington, DC 20375, United States
| | - Debra R Rolison
- Surface Chemistry Branch, Code 6170, U.S. Naval Research Laboratory, Washington, DC 20375, United States
| | - Justin C Lytle
- Chemistry Department, Pacific Lutheran University , Tacoma, Washington 98447, United States
| | - Jeffrey W Long
- Surface Chemistry Branch, Code 6170, U.S. Naval Research Laboratory, Washington, DC 20375, United States
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69
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Mitchell EC, Dunaway LE, McCarty GS, Sombers LA. Spectroelectrochemical Characterization of the Dynamic Carbon-Fiber Surface in Response to Electrochemical Conditioning. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7838-7846. [PMID: 28715197 DOI: 10.1021/acs.langmuir.7b01443] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The effects of electrochemical preconditioning of P-55 pitch-based carbon-fiber microelectrodes were quantitatively examined in this study. Microstructural characterization of the electrode surface was done using Raman spectroscopy and scanning electron microscopy. Electrochemical performance was evaluated using cyclic voltammetry. The data show that application of positive potentials provides beneficial structural modifications to the electrode surface. Electrodes that were preconditioned using a static potential of +1.0 V exhibited enhanced sensitivity and electron transfer properties when compared to electrodes conditioned for the same amount of time with dynamic (triangular) waveforms reaching +1.0 V. Conditioning elicited microstructural changes to the electrode surface that were dependent on the amount of time spent at potentials greater than ∼1.0 V. Importantly, the data demonstrate that the carbon-fiber microstructure is dynamic. It is able to quickly and continuously undergo rapid structural reorganization as potential is applied, repeatedly alternating between a relatively ordered state and one that exhibits greater disorder in response to applied electrochemical potentials that span the range commonly used in voltammetric experiments.
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Affiliation(s)
- Edwin C Mitchell
- Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Lars E Dunaway
- Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Gregory S McCarty
- Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Leslie A Sombers
- Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States
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71
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Ryl J, Zielinski A, Burczyk L, Bogdanowicz R, Ossowski T, Darowicki K. Chemical-Assisted Mechanical Lapping of Thin Boron-Doped Diamond Films: A Fast Route Toward High Electrochemical Performance for Sensing Devices. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.05.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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72
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Tan SY, Zhang J, Bond AM, Macpherson JV, Unwin PR. Influence of Tip and Substrate Properties and Nonsteady-State Effects on Nanogap Kinetic Measurements: Response to Comment on “Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements”. Anal Chem 2017. [PMID: 28644008 DOI: 10.1021/acs.analchem.7b01664] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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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73
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Vagin MY, Sekretaryova AN, Ivanov IG, Håkansson A, Iakimov T, Syväjärvi M, Yakimova R, Lundström I, Eriksson M. Monitoring of epitaxial graphene anodization. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.04.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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74
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Yamasaki R, Takatsuji Y, Morimoto M, Ishikawa S, Fujinami T, Haruyama T. Sustainable process for functional group introduction onto HOPG by exposing OH and 1O2 using a radical vapor reactor (RVR) without any chemical reagents. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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75
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Bartali R, Otyepka M, Pykal M, Lazar P, Micheli V, Gottardi G, Laidani N. Interaction of the Helium, Hydrogen, Air, Argon, and Nitrogen Bubbles with Graphite Surface in Water. ACS APPLIED MATERIALS & INTERFACES 2017; 9:17517-17525. [PMID: 28474883 DOI: 10.1021/acsami.6b16493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The interaction of the confined gas with solid surface immersed in water is a common theme of many important fields such as self-cleaning surface, gas storage, and sensing. For that reason, we investigated the gas-graphite interaction in the water medium. The graphite surface was prepared by mechanical exfoliation of highly oriented pyrolytic graphite (HOPG). The surface chemistry and morphology were studied by X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy. The surface energy of HOPG was estimated by contact angle measurements using the Owens-Wendt method. The interaction of gases (Ar, He, H2, N2, and air) with graphite was studied by a captive bubble method, in which the gas bubble was in contact with the exfoliated graphite surface in water media. The experimental data were corroborated by molecular dynamics simulations and density functional theory calculations. The surface energy of HOPG equaled to 52.8 mJ/m2 and more of 95% of the surface energy was attributed to dispersion interactions. The results on gas-surface interaction indicated that HOPG surface had gasphilic behavior for helium and hydrogen, while gasphobic behavior for argon and nitrogen. The results showed that the variation of the gas contact angle was related to the balance between the gas-surface and gas-gas interaction potentials. For helium and hydrogen the gas-surface interaction was particularly high compared to gas-gas interaction and this promoted the favorable interaction with graphite surface.
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Affiliation(s)
- Ruben Bartali
- Department of Physics, University of Trento , Via Sommarive 14 Povo, 38123 Trento, Italy
- Fondazione Bruno Kessler , Center of Materials and Microsystems, Via Sommarive 18, 38123 Trento, Italy
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Palacký University Olomouc , tř. 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Martin Pykal
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Palacký University Olomouc , tř. 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Petr Lazar
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Palacký University Olomouc , tř. 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Victor Micheli
- Fondazione Bruno Kessler , Center of Materials and Microsystems, Via Sommarive 18, 38123 Trento, Italy
| | - Gloria Gottardi
- Fondazione Bruno Kessler , Center of Materials and Microsystems, Via Sommarive 18, 38123 Trento, Italy
| | - Nadhira Laidani
- Fondazione Bruno Kessler , Center of Materials and Microsystems, Via Sommarive 18, 38123 Trento, Italy
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76
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Chakri S, Patel AN, Frateur I, Kanoufi F, Sutter EMM, Tran TTM, Tribollet B, Vivier V. Imaging of a Thin Oxide Film Formation from the Combination of Surface Reflectivity and Electrochemical Methods. Anal Chem 2017; 89:5303-5310. [PMID: 28406015 DOI: 10.1021/acs.analchem.6b04921] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Sara Chakri
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
| | - Anisha N. Patel
- Sorbonne Paris
Cité, Paris Diderot University, Interfaces, Traitements, Organisation
et Dynamique des Systèmes Laboratory, CNRS-UMR 7086, 15 rue J. A. Baif, 75013 Paris, France
| | - Isabelle Frateur
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
| | - Frédéric Kanoufi
- Sorbonne Paris
Cité, Paris Diderot University, Interfaces, Traitements, Organisation
et Dynamique des Systèmes Laboratory, CNRS-UMR 7086, 15 rue J. A. Baif, 75013 Paris, France
| | - Eliane M. M. Sutter
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
| | - T. T. Mai Tran
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
| | - Bernard Tribollet
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
| | - Vincent Vivier
- Sorbonne Universités,
UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes
Electrochimiques, 4 place Jussieu, F-75005, Paris, France
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77
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Ricardo KB, Xu A, Salim M, Zhou F, Liu H. Deposition of DNA Nanostructures on Highly Oriented Pyrolytic Graphite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3991-3997. [PMID: 28406032 DOI: 10.1021/acs.langmuir.6b03836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the deposition of DNA origami nanostructures on highly oriented pyrolytic graphite (HOPG). The DNA origami goes through a structural rearrangement and the DNA base is exposed to interact with the graphite surface. Exposure to ambient air, which is known to result in a hydrophilic-to-hydrophobic wetting transition of HOPG, does not significantly impact the deposition yield or the shape deformation of DNA nanostructures. The deposited DNA nanostructures maintain their morphology for at least a week and promote site-selective chemical vapor deposition of SiO2. This process is potentially useful for a range of applications that include but are not limited to nanostructure fabrication, sensing, and electronic and surface engineering.
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Affiliation(s)
- Karen B Ricardo
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Anqin Xu
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Muhammad Salim
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Feng Zhou
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Haitao Liu
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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78
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Nellist MR, Chen Y, Mark A, Gödrich S, Stelling C, Jiang J, Poddar R, Li C, Kumar R, Papastavrou G, Retsch M, Brunschwig BS, Huang Z, Xiang C, Boettcher SW. Atomic force microscopy with nanoelectrode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging. NANOTECHNOLOGY 2017; 28:095711. [PMID: 28139467 DOI: 10.1088/1361-6528/aa5839] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Multimodal nano-imaging in electrochemical environments is important across many areas of science and technology. Here, scanning electrochemical microscopy (SECM) using an atomic force microscope (AFM) platform with a nanoelectrode probe is reported. In combination with PeakForce tapping AFM mode, the simultaneous characterization of surface topography, quantitative nanomechanics, nanoelectronic properties, and electrochemical activity is demonstrated. The nanoelectrode probe is coated with dielectric materials and has an exposed conical Pt tip apex of ∼200 nm in height and of ∼25 nm in end-tip radius. These characteristic dimensions permit sub-100 nm spatial resolution for electrochemical imaging. With this nanoelectrode probe we have extended AFM-based nanoelectrical measurements to liquid environments. Experimental data and numerical simulations are used to understand the response of the nanoelectrode probe. With PeakForce SECM, we successfully characterized a surface defect on a highly-oriented pyrolytic graphite electrode showing correlated topographical, electrochemical and nanomechanical information at the highest AFM-SECM resolution. The SECM nanoelectrode also enabled the measurement of heterogeneous electrical conductivity of electrode surfaces in liquid. These studies extend the basic understanding of heterogeneity on graphite/graphene surfaces for electrochemical applications.
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Affiliation(s)
- Michael R Nellist
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403, United States
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79
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Koçak I. Characterization of the Reduction of Oxygen at Anthraquinone-Modified Glassy Carbon and Highly Oriented Pyrolytic Graphite Electrodes. ANAL LETT 2017. [DOI: 10.1080/00032719.2016.1236126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Izzet Koçak
- Faculty of Pharmacy, Bülent Ecevit University, Zonguldak, Turkey
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80
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Tan SY, Unwin PR, Macpherson JV, Zhang J, Bond AM. Probing Electrode Heterogeneity Using Fourier-Transformed Alternating Current Voltammetry: Application to a Dual-Electrode Configuration. Anal Chem 2017; 89:2830-2837. [DOI: 10.1021/acs.analchem.6b03924] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sze-yin Tan
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Julie V. Macpherson
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Jie Zhang
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Alan M. Bond
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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81
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Kislenko SA, Pavlov SV. Effect of carbon cathode morphology on the electrode/electrolyte interface structure. HIGH ENERGY CHEMISTRY 2017. [DOI: 10.1134/s0018143917010052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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82
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Yivlialin R, Bussetti G, Penconi M, Bossi A, Ciccacci F, Finazzi M, Duò L. Vacuum-Deposited Porphyrin Protective Films on Graphite: Electrochemical Atomic Force Microscopy Investigation during Anion Intercalation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:4100-4105. [PMID: 28045244 DOI: 10.1021/acsami.6b12359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The development of graphene products promotes a renewed interest toward the use of graphite in addition to the historical one for its proven viability as battery electrode. However, when exposed to harsh conditions, the graphite surface ages in ways that still need to be fully characterized. In applications to batteries, to optimize the electrode performances in acid solutions, different surface functionalizations have been studied. Among them, aromatic molecules have been recently proposed. In this communication, we report on the protective effect exerted by a physical-vapor-deposited porphyrin layer. Metal-free tetra-phenyl-porphyrins were deposited on a highly oriented pyrolytic graphite crystal to study the modifications that occur during anion intercalation in graphite. The graphite electrode was plunged in an electrolyte solution of 1 M sulfuric acid and subjected to cyclic voltammetry. The results indicate that blister formation, the characteristic swelling of graphite surface induced by anion intercalation, is significantly perturbed by the porphyrin overlayer; the process is inhibited in those areas where the protective porphyrin film is present. We ascribe the inhibition of the anion intercalation to the protective porphyrin wetting layer.
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Affiliation(s)
- Rossella Yivlialin
- Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Gianlorenzo Bussetti
- Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Marta Penconi
- Institute of Molecular Science and Technologies of the CNR (ISTM) , PST via G. Fantoli 16/15, 20138 Milano, Italy
- SmartMatLab Centre@ISTM, Via C. Golgi 19, 20133 Milano, Italy
| | - Alberto Bossi
- Institute of Molecular Science and Technologies of the CNR (ISTM) , PST via G. Fantoli 16/15, 20138 Milano, Italy
- SmartMatLab Centre@ISTM, Via C. Golgi 19, 20133 Milano, Italy
| | - Franco Ciccacci
- Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Marco Finazzi
- Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Lamberto Duò
- Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy
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83
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Kozbial A, Trouba C, Liu H, Li L. Characterization of the Intrinsic Water Wettability of Graphite Using Contact Angle Measurements: Effect of Defects on Static and Dynamic Contact Angles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:959-967. [PMID: 28071919 DOI: 10.1021/acs.langmuir.6b04193] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Elucidating the intrinsic water wettability of the graphitic surface has increasingly attracted research interests, triggered by the recent finding that the well-established hydrophobicity of graphitic surfaces actually results from airborne hydrocarbon contamination. Currently, static water contact angle (WCA) is often used to characterize the intrinsic water wettability of graphitic surfaces. In the current paper, we show that because of the existence of defects, static WCA does not necessarily characterize the intrinsic water wettability. Freshly exfoliated graphite of varying qualities, characterized using atomic force microscopy and Raman spectroscopy, was studied using static, advancing, and receding WCA measurements. The results showed that graphite of different qualities (i.e., defect density) always has a similar advancing WCA, but it could have very different static and receding WCAs. This finding indicates that defects play an important role in contact angle measurements, and the static contact angle does not always represent the intrinsic water wettability of pristine graphite. On the basis of the experimental results, a qualitative model is proposed to explain the effect of defects on static, advancing, and receding contact angles. The model suggests that the advancing WCA reflects the intrinsic water wettability of pristine (defect-free) graphite. Our results showed that the advancing WCA for pristine graphite is 68.6°, which indicates that graphitic carbon is intrinsically mildly hydrophilic.
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Affiliation(s)
- Andrew Kozbial
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Charlie Trouba
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Haitao Liu
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Lei Li
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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84
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Peng Z, Yang R, Kim MA, Li L, Liu H. Influence of O2, H2O and airborne hydrocarbons on the properties of selected 2D materials. RSC Adv 2017. [DOI: 10.1039/c7ra02130e] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Adsorption of molecules from the ambient environment significantly changes the optical, electrical, electrochemical, and tribological properties of 2D materials.
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Affiliation(s)
- Zhenbo Peng
- Chemical Engineering College
- Ningbo Polytechnic
- Ningbo
- P. R. China
- Department of Chemistry
| | - Rui Yang
- Department of Chemistry
- Beihua University
- Jilin
- P. R. China
- Department of Chemistry
| | - Min A. Kim
- Department of Chemistry
- University of Pittsburgh
- Pittsburgh
- USA
| | - Lei Li
- Department of Chemical & Petroleum Engineering
- Swanson School of Engineering
- University of Pittsburgh
- Pittsburgh
- USA
| | - Haitao Liu
- Department of Chemistry
- University of Pittsburgh
- Pittsburgh
- USA
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85
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Ravenhill ER, Adobes-Vidal M, Unwin PR. Calcium carbonate crystallisation at charged graphite surfaces. Chem Commun (Camb) 2017; 53:12552-12555. [DOI: 10.1039/c7cc07441g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
For identical solution conditions, the crystallisation of calcium carbonate (polymorph and crystal orientation) at Highly Oriented Pyrolytic Graphite substrates is highly dependent on substrate surface charge.
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Affiliation(s)
| | | | - P. R. Unwin
- Department of Chemistry
- University of Warwick
- Coventry
- UK
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86
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Molena de Assis C, Ho TH, de Melo HG, Keddam M, Turmine M, Vivier V. Electrochemical Impedance Spectroscopy in a Droplet of Solution for the Investigation of Liquid/Solid Interface. Anal Chem 2016; 88:12108-12115. [PMID: 28193063 DOI: 10.1021/acs.analchem.6b02795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The local electrochemical behavior of a solid-liquid interface can be studied by electrochemical impedance spectroscopy (EIS). The investigated surface area can be delimited by adding a drop of solution, which forms an interface between the liquid drop and the working electrode, and performing the measurements inside. The size of the drop must be sufficiently small for a simultaneous wettability characterization (from the contact angle measurement) and appropriately large so that wettability is not influenced by the presence of the working and the counter electrode inserted in the droplet. In this work, we showed that EIS measurements can be performed in a solution droplet of 2 to 4 μL, although the electrochemical cell lacks the usual geometry. For our measurements, we studied a model system consisting of a KCl aqueous solution of [Fe(CN)6]3-/4- redox couple at a Pt electrode. All the results were compared with those obtained for a bulk configuration. The sessile drop configuration and the EIS response were modeled using finite element method for different electrode sizes and configurations to account for electrochemical kinetics and both current and potential distributions.
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Affiliation(s)
- Camila Molena de Assis
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 Place Jussieu, F-75005 Paris, France.,Departamento de Eng. Metalúrgica e de Materiais, Universidade de São Paulo , Av. Prof. Mello Moraes, n. 2463, CEP 05508-030 São Paulo, São Paulo, Brazil
| | - Thu Huong Ho
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 Place Jussieu, F-75005 Paris, France
| | - Hercilio Gomes de Melo
- Departamento de Eng. Metalúrgica e de Materiais, Universidade de São Paulo , Av. Prof. Mello Moraes, n. 2463, CEP 05508-030 São Paulo, São Paulo, Brazil
| | - Michel Keddam
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 Place Jussieu, F-75005 Paris, France
| | - Mireille Turmine
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 Place Jussieu, F-75005 Paris, France
| | - Vincent Vivier
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 Place Jussieu, F-75005 Paris, France
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87
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Abstract
Graphitic carbons are important solid materials with myriad applications including electrodes, adsorbents, catalyst support, and solid lubricants. Understanding the interaction between water and graphitic carbons is critically important for both fundamental material characterization and practical device fabrication because the water-graphitic interface is essential to many applications. Research interests in graphene and carbon nanotubes over the past decades have brought renewed interest to elucidate wettability of graphitic carbons and understand their interaction with the surrounding environment. Research on this topic can be traced back to the 1940s, and the prevailing notion has been that graphitic carbons are hydrophobic. Though there have been different voices, this conclusion is supported by many previous water contact angle tests and well accepted by the community since sp2 carbon is nonpolar in nature. However, recent results from our groups showed that graphitic surfaces are intrinsically mildly hydrophilic and adsorbed hydrocarbon contaminants from the ambient air render the surface hydrophobic. This unexpected finding challenges the long-lasting conception and could completely change the way graphitic materials are made, modeled, and modified. With several other research groups reporting similar findings, it is important for the community to realize the importance of airborne contamination on the surface-related properties of graphitic materials and revisit the intrinsic water-graphite interaction. This Account aims to summarize our recent work on water wettability of graphitic surfaces and discuss future research directions toward understanding the intrinsic water-graphite interaction. Historical perspective will first be provided highlighting the long accepted notion that graphite is hydrophobic along with a few reports suggesting otherwise. Next, our recent experimental data will be presented showing that pristine graphene and graphite are mildly hydrophilic; chemical analysis showed that hydrocarbons adsorb onto the clean surfaces thus rendering them hydrophobic. These results are further rationalized by analyzing the change in surface energy of the graphitic surfaces before and after hydrocarbon contamination. Facile methods to remove hydrocarbons from a contaminated surface will be discussed along with a convenient water treatment method that we developed to inhibit hydrocarbon adsorption onto a pristine graphitic surface. Implications of contamination will be illustrated through comparing the electrochemical activity of pristine and contaminated graphite. Lastly, consequences of these findings and future research directions to address a few important unanswered questions will be discussed.
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Affiliation(s)
- Andrew Kozbial
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Feng Zhou
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Zhiting Li
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Haitao Liu
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Lei Li
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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88
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Takahashi Y, Kumatani A, Shiku H, Matsue T. Scanning Probe Microscopy for Nanoscale Electrochemical Imaging. Anal Chem 2016; 89:342-357. [DOI: 10.1021/acs.analchem.6b04355] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yasufumi Takahashi
- Division
of Electrical Engineering and Computer Science, Kanazawa University, Kanazawa 920-1192, Japan
- Precursory
Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
| | - Akichika Kumatani
- Advanced
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Graduate
School of Environmental Studies, Tohoku University, Sendai 980-8579, Japan
| | - Hitoshi Shiku
- Department
of Applied Chemistry, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
| | - Tomokazu Matsue
- Advanced
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Graduate
School of Environmental Studies, Tohoku University, Sendai 980-8579, Japan
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89
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Gao YX, Wu D, Yang YX, Wang WJ, Xie SY, Shiu KK, Shi K. Mechanistic study on the interfacial variation of carbon electrode under electrochemical oxidation. J Electroanal Chem (Lausanne) 2016. [DOI: 10.1016/j.jelechem.2016.11.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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90
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E SP, Kim YR, Perry D, Bentley CL, Unwin PR. Nanoscale Electrocatalysis of Hydrazine Electro-Oxidation at Blistered Graphite Electrodes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:30458-30466. [PMID: 27739301 DOI: 10.1021/acsami.6b10940] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There is great interest in finding and developing new, efficient, and more active electrocatalytic materials. Surface modification of highly oriented pyrolytic graphite, through the introduction of surface "blisters", is demonstrated to result in an electrode material with greatly enhanced electrochemical activity. The increased electrochemical activity of these blisters, which are produced by electro-oxidation in HClO4, is revealed through the use of scanning electrochemical cell microscopy (SECCM), coupled with complementary techniques (optical microscopy, field emission-scanning electron microscopy, Raman spectroscopy, and atomic force microscopy). The use of a linear sweep voltammetry (LSV)-SECCM scan regime allows for dynamic electrochemical mapping, where a voltammogram is produced at each pixel, from which movies consisting of spatial electrochemical currents, at a series of applied potentials, are produced. The measurements reveal significantly enhanced electrocatalytic activity at blisters when compared to the basal planes, with a significant cathodic shift in the onset potential of the hydrazine electro-oxidation reaction. The improved electrochemical activity of the hollow structure of blistered graphite could be explained by the increased adsorption of protonated hydrazine at oxygenated defect sites, the ease of ion-solvent intercalation/deintercalation, and the reduced susceptibility to N2 nanobubble attachment (as a product of the reaction). This study highlights the capability of electrochemistry to tailor the surface structure of graphite and presents a new electrocatalyst for hydrazine electro-oxidation.
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Affiliation(s)
| | - Yang-Rae Kim
- Department of Chemistry, Kwangwoon University , Seoul 01897, Republic of Korea
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91
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Zou Y, Walton AS, Kinloch IA, Dryfe RAW. Investigation of the Differential Capacitance of Highly Ordered Pyrolytic Graphite as a Model Material of Graphene. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11448-11455. [PMID: 27760294 DOI: 10.1021/acs.langmuir.6b02910] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A study of the differences among the capacitances of freshly exfoliated highly ordered pyrolytic graphite (HOPG, sample denoted FEG), HOPG aged in air (denoted AAG), and HOPG aged in an inert atmosphere (hereafter IAG) is presented in this work. The FEG is found to be more hydrophilic than AAG and IAG because the aqueous electrolyte contact angle (CA) increases from 61.7° to 72.5° and 81.8° after aging in Ar and air, respectively. Electrochemical impedance spectroscopy shows the FEG has an intrinsic capacitance (6.0 μF cm-2 at the potential of minimum capacitance) higher than those of AAG (4.3 μF cm-2) and IAG (4.7 μF cm-2). The observed changes in the electrochemical response are correlated with spectroscopic characterization (Raman spectroscopy and X-ray photoelectron spectroscopy), which show that the surface of HOPG was doped or contaminated after exposure to air. Taken together, these changes upon atmospheric exposure are attributed to oxygen molecule, moisture, and airborne organic contaminations: high-vacuum annealing was applied for the removal of the adsorbed contaminants. It was found that annealing the aged sample at 500 °C leads to partial removal of the contaminants, as gauged by the recovery of the measured capacitance. To the best of our knowledge, this is first study of the effect of the airborne contaminants on the capacitance of carbon-based materials.
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Affiliation(s)
- Yuqin Zou
- School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
| | - Alex S Walton
- School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
- Photon Science Institute, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
| | - Ian A Kinloch
- School of Materials, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
| | - Robert A W Dryfe
- School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
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92
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Unwin PR, Güell AG, Zhang G. Nanoscale Electrochemistry of sp(2) Carbon Materials: From Graphite and Graphene to Carbon Nanotubes. Acc Chem Res 2016; 49:2041-8. [PMID: 27501067 DOI: 10.1021/acs.accounts.6b00301] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed. This Account advocates the use of emerging electrochemical imaging techniques and confined electrochemical cell formats that have considerable potential to reveal major new perspectives on the intrinsic electrochemical activity of carbon materials, with unprecedented detail and spatial resolution. These techniques allow particular features on a surface to be targeted and models of structure-activity to be developed and tested on a wide range of length scales and time scales. When high resolution electrochemical imaging data are combined with information from other microscopy and spectroscopy techniques applied to the same area of an electrode surface, in a correlative-electrochemical microscopy approach, highly resolved and unambiguous pictures of electrode activity are revealed that provide new views of the electrochemical properties of carbon materials. With a focus on major sp(2) carbon materials, graphite, graphene, and single walled carbon nanotubes (SWNTs), this Account summarizes recent advances that have changed understanding of interfacial electrochemistry at carbon electrodes including: (i) Unequivocal evidence for the high activity of the basal surface of highly oriented pyrolytic graphite (HOPG), which is at least as active as noble metal electrodes (e.g., platinum) for outer-sphere redox processes. (ii) Demonstration of the high activity of basal plane HOPG toward other reactions, with no requirement for catalysis by step edges or defects, as exemplified by studies of proton-coupled electron transfer, redox transformations of adsorbed molecules, surface functionalization via diazonium electrochemistry, and metal electrodeposition. (iii) Rationalization of the complex interplay of different factors that determine electrochemistry at graphene, including the source (mechanical exfoliation from graphite vs chemical vapor deposition), number of graphene layers, edges, electronic structure, redox couple, and electrode history effects. (iv) New methodologies that allow nanoscale electrochemistry of 1D materials (SWNTs) to be related to their electronic characteristics (metallic vs semiconductor SWNTs), size, and quality, with high resolution imaging revealing the high activity of SWNT sidewalls and the importance of defects for some electrocatalytic reactions (e.g., the oxygen reduction reaction). The experimental approaches highlighted for carbon electrodes are generally applicable to other electrode materials and set a new framework and course for the study of electrochemical and interfacial processes.
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Affiliation(s)
- Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Aleix G. Güell
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
- School
of Engineering and Built Environment, Glasgow Caledonian University, Glasgow G4 0BA, United Kingdom
| | - Guohui Zhang
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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Hui J, Zhou X, Bhargava R, Chinderle A, Zhang J, Rodríguez-López J. Kinetic Modulation of Outer-Sphere Electron Transfer Reactions on Graphene Electrode with a Sub-surface Metal Substrate. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.06.134] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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94
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Rowley-Neale SJ, Brownson DAC, Banks CE. Defining the origins of electron transfer at screen-printed graphene-like and graphite electrodes: MoO2 nanowire fabrication on edge plane sites reveals electrochemical insights. NANOSCALE 2016; 8:15241-51. [PMID: 27487988 DOI: 10.1039/c6nr04220a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Molybdenum (di)oxide (MoO2) nanowires are fabricated onto graphene-like and graphite screen-printed electrodes (SPEs) for the first time, revealing crucial insights into the electrochemical properties of carbon/graphitic based materials. Distinctive patterns observed in the electrochemical process of nanowire decoration show that electron transfer occurs predominantly on edge plane sites when utilising SPEs fabricated/comprised of graphitic materials. Nanowire fabrication along the edge plane sites (and on edge plane like-sites/defects) of graphene/graphite is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Comparison of the heterogeneous electron transfer (HET) rate constants (k°) at unmodified and nanowire coated SPEs show a reduction in the electrochemical reactivity of SPEs when the edge plane sites are effectively blocked/coated with MoO2. Throughout the process, the basal plane sites of the graphene/graphite electrodes remain relatively uncovered; except when the available edge plane sites have been utilised, in which case MoO2 deposition grows from the edge sites covering the entire surface of the electrode. This work clearly illustrates the distinct electron transfer properties of edge and basal plane sites on graphitic materials, indicating favourable electrochemical reactivity at the edge planes in contrast to limited reactivity at the basal plane sites. In addition to providing fundamental insights into the electron transfer properties of graphite and graphene-like SPEs, the reported simple, scalable, and cost effective formation of unique and intriguing MoO2 nanowires realised herein is of significant interest for use in both academic and commercial applications.
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Affiliation(s)
- Samuel J Rowley-Neale
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK.
| | - Dale A C Brownson
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK.
| | - Craig E Banks
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK.
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95
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Zhang G, Walker M, Unwin PR. Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7476-84. [PMID: 27406680 DOI: 10.1021/acs.langmuir.6b01506] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We demonstrate low-voltage electrowetting at the surface of freshly cleaved highly oriented pyrolytic graphite (HOPG). Using cyclic voltammetry (CV), electrowetting of a droplet of a sodium perchlorate solution is observed at moderately positive potentials on high-quality (low step edge coverage) HOPG, leading to significant changes in the contact angle and relative contact diameter that are comparable to the results of the widely studied electrowetting on dielectric (EWOD) system, but over a much lower voltage range. The electrowetting behavior is found to be reasonably fast, reversible, and repeatable for at least 20 cyclic scans (maximum tested). In contrast to classical electrowetting, e.g., EWOD, the electrowetting of the droplet on HOPG occurs with the intercalation/deintercalation of anions between the graphene layers of graphite, driven by the applied potential, observed in the CV response, and detected by X-ray photoelectron spectroscopy. The electrowetting behavior is strongly influenced by those factors that affect the extent of the intercalation/deintercalation of ions on graphite, such as potential range scan rate, potential polarity, quality of the HOPG substrate (step edge density and step height), and type of anion in the solution. In addition to perchlorate, sulfate salts also promote electrowetting, but some other salts do not. Our findings suggest a new mechanism for electrowetting based on ion intercalation, and the results are important to fundamental electrochemistry as well as to diversifying the means by which electrowetting can be controlled and applied.
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Affiliation(s)
- Guohui Zhang
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Marc Walker
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Patrick R Unwin
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
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96
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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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98
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Patil RA, Chang CP, Devan RS, Liou Y, Ma YR. Impact of Nanosize on Supercapacitance: Study of 1D Nanorods and 2D Thin-Films of Nickel Oxide. ACS APPLIED MATERIALS & INTERFACES 2016; 8:9872-80. [PMID: 27028491 DOI: 10.1021/acsami.6b00487] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We synthesized unique one-dimensional (1D) nanorods and two-dimensional (2D) thin-films of NiO on indium-tin-oxide thin-films using a hot-filament metal-oxide vapor deposition technique. The 1D nanorods have an average width and length of ∼100 and ∼500 nm, respectively, and the densely packed 2D thin-films have an average thickness of ∼500 nm. The 1D nanorods perform as parallel units for charge storing. However, the 2D thin-films act as one single unit for charge storing. The 2D thin-films possess a high specific capacitance of ∼746 F/g compared to 1D nanorods (∼230 F/g) using galvanostatic charge-discharge measurements at a current density of 3 A/g. Because the 1D NiO nanorods provide more plentiful surface areas than those of the 2D thin-films, they are fully active at the first few cycles. However, the capacitance retention of the 1D nanorods decays faster than that of the 2D thin-films. Also, the 1D NiO nanorods suffer from instability due to the fast electrochemical dissolution and high nanocontact resistance. Electrochemical impedance spectroscopy verifies that the low dimensionality of the 1D NiO nanorods induces the unavoidable effects that lead them to have poor supercapacitive performances. On the other hand, the slow electrochemical dissolution and small contact resistance in the 2D NiO thin-films favor to achieve high specific capacitance and great stability.
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Affiliation(s)
- Ranjit A Patil
- Department of Physics, National Dong Hwa University , Hualien 97401, Taiwan
| | - Cheng-Ping Chang
- Department of Physics, National Dong Hwa University , Hualien 97401, Taiwan
| | - Rupesh S Devan
- Department of Physics, National Dong Hwa University , Hualien 97401, Taiwan
| | - Yung Liou
- Institute of Physics, Academia Sinica , Taipei 11529, Taiwan
| | - Yuan-Ron Ma
- Department of Physics, National Dong Hwa University , Hualien 97401, Taiwan
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99
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Nucleation processes of nanobubbles at a solid/water interface. Sci Rep 2016; 6:24651. [PMID: 27090291 PMCID: PMC4835695 DOI: 10.1038/srep24651] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/04/2016] [Indexed: 11/11/2022] Open
Abstract
Experimental investigations of hydrophobic/water interfaces often return controversial results, possibly due to the unknown role of gas accumulation at the interfaces. Here, during advanced atomic force microscopy of the initial evolution of gas-containing structures at a highly ordered pyrolytic graphite/water interface, a fluid phase first appeared as a circular wetting layer ~0.3 nm in thickness and was later transformed into a cap-shaped nanostructure (an interfacial nanobubble). Two-dimensional ordered domains were nucleated and grew over time outside or at the perimeter of the fluid regions, eventually confining growth of the fluid regions to the vertical direction. We determined that interfacial nanobubbles and fluid layers have very similar mechanical properties, suggesting low interfacial tension with water and a liquid-like nature, explaining their high stability and their roles in boundary slip and bubble nucleation. These ordered domains may be the interfacial hydrophilic gas hydrates and/or the long-sought chemical surface heterogeneities responsible for contact line pinning and contact angle hysteresis. The gradual nucleation and growth of hydrophilic ordered domains renders the original homogeneous hydrophobic/water interface more heterogeneous over time, which would have great consequence for interfacial properties that affect diverse phenomena, including interactions in water, chemical reactions, and the self-assembly and function of biological molecules.
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100
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Rüdiger C, Favaro M, Valero-Vidal C, Calvillo L, Bozzolo N, Jacomet S, Hejny C, Gregoratti L, Amati M, Agnoli S, Granozzi G, Kunze-Liebhäuser J. Fabrication of Ti substrate grain dependent C/TiO2 composites through carbothermal treatment of anodic TiO2. Phys Chem Chem Phys 2016; 18:9220-31. [PMID: 26975480 DOI: 10.1039/c5cp07727c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Composite materials of titania and graphitic carbon, and their optimized synthesis are highly interesting for application in sustainable energy conversion and storage. We report on planar C/TiO2 composite films that are prepared on a polycrystalline titanium substrate by carbothermal treatment of compact anodic TiO2 with acetylene. This thin film material allows for the study of functional properties of C/TiO2 as a function of chemical composition and structure. The chemical and structural properties of the composite on top of individual Ti substrate grains are examined by scanning photoelectron microscopy and micro-Raman spectroscopy. Through comparison of these data with electron backscatter diffraction, it is found that the amount of generated carbon and the grade of anodic film crystallinity correlate with the crystallographic orientation of the Ti substrate grains. On top of Ti grains with ∼(0001) orientations the anodic TiO2 exhibits the highest grade of crystallinity, and the composite contains the highest fraction of graphitic carbon compared to Ti grains with other orientations. This indirect effect of the Ti substrate grain orientation yields new insights into the activity of TiO2 towards the decomposition of carbon precursors.
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Affiliation(s)
- Celine Rüdiger
- Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany. and Institut für Physikalische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
| | - Marco Favaro
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Carlos Valero-Vidal
- Institut für Physikalische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
| | - Laura Calvillo
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Nathalie Bozzolo
- MINES ParisTech, PSL - Research University, CEMEF - Centre de Mise en Forme des Matériaux, CNRS UMR 7635, CS 10207 Rue Claude Daunesse, 06904 Sophia Antipolis Cedex, France
| | - Suzanne Jacomet
- MINES ParisTech, PSL - Research University, CEMEF - Centre de Mise en Forme des Matériaux, CNRS UMR 7635, CS 10207 Rue Claude Daunesse, 06904 Sophia Antipolis Cedex, France
| | - Clivia Hejny
- Institut für Mineralogie und Petrographie, Leopold-Franzens-Universität Innsbruck, Innrain 52d, 6020 Innsbruck, Austria
| | - Luca Gregoratti
- Elettra - Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, 34149 Trieste, Italy
| | - Matteo Amati
- Elettra - Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, 34149 Trieste, Italy
| | - Stefano Agnoli
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Gaetano Granozzi
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Julia Kunze-Liebhäuser
- Institut für Physikalische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
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