51
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Perera RT, Arcadia CE, Rosenstein JK. Probing the nucleation, growth, and evolution of hydrogen nanobubbles at single catalytic sites. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.07.063] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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52
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Dayeh M, Ghavidel MRZ, Mauzeroll J, Schougaard SB. Micropipette Contact Method to Investigate High-Energy Cathode Materials by using an Ionic Liquid. ChemElectroChem 2018. [DOI: 10.1002/celc.201800750] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Malak Dayeh
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal H3 A 0B8, QC Canada
| | - M. R. Zamanzad Ghavidel
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal H3 A 0B8, QC Canada
- Département de Chimie; Université du Québec à Montréal; NanoQam Research Center Montreal H3C 3P8, QC Canada
| | - Janine Mauzeroll
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal H3 A 0B8, QC Canada
| | - Steen B. Schougaard
- Département de Chimie; Université du Québec à Montréal; NanoQam Research Center Montreal H3C 3P8, QC Canada
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53
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Zhang S, Li M, Su B, Shao Y. Fabrication and Use of Nanopipettes in Chemical Analysis. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2018; 11:265-286. [PMID: 29894227 DOI: 10.1146/annurev-anchem-061417-125840] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This review summarizes progress in the fabrication, modification, characterization, and applications of nanopipettes since 2010. A brief history of nanopipettes is introduced, and the details of fabrication, modification, and characterization of nanopipettes are provided. Applications of nanopipettes in chemical analysis are the focus in several cases, including recent progress in imaging; in the study of single molecules, single nanoparticles, and single cells; in fundamental investigations of charge transfer (ion and electron) reactions at liquid/liquid interfaces; and as hyphenated techniques combined with other methods to study the mechanisms of complicated electrochemical reactions and to conduct bioanalysis.
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Affiliation(s)
- Shudong Zhang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China;
| | - Mingzhi Li
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China;
| | - Bin Su
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University, Hangzhou 310058, China;
| | - Yuanhua Shao
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China;
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54
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Bentley CL, Perry D, Unwin PR. Stability and Placement of Ag/AgCl Quasi-Reference Counter Electrodes in Confined Electrochemical Cells. Anal Chem 2018; 90:7700-7707. [PMID: 29808685 DOI: 10.1021/acs.analchem.8b01588] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nanoelectrochemistry is an important and growing branch of electrochemistry that encompasses a number of key research areas, including (electro)catalysis, energy storage, biomedical/environmental sensing, and electrochemical imaging. Nanoscale electrochemical measurements are often performed in confined environments over prolonged experimental time scales with nonisolated quasi-reference counter electrodes (QRCEs) in a simplified two-electrode format. Herein, we consider the stability of commonly used Ag/AgCl QRCEs, comprising an AgCl-coated wire, in a nanopipet configuration, which simulates the confined electrochemical cell arrangement commonly encountered in nanoelectrochemical systems. Ag/AgCl QRCEs possess a very stable reference potential even when used immediately after preparation and, when deployed in Cl- free electrolyte media (e.g., 0.1 M HClO4) in the scanning ion conductance microscopy (SICM) format, drift by only ca. 1 mV h-1 on the several hours time scale. Furthermore, contrary to some previous reports, when employed in a scanning electrochemical cell microscopy (SECCM) format (meniscus contact with a working electrode surface), Ag/AgCl QRCEs do not cause fouling of the surface (i.e., with soluble redox byproducts, such as Ag+) on at least the 6 h time scale, as long as suitable precautions with respect to electrode handling and placement within the nanopipet are observed. These experimental observations are validated through finite element method (FEM) simulations, which consider Ag+ transport within a nanopipet probe in the SECCM and SICM configurations. These results confirm that Ag/AgCl is a stable and robust QRCE in confined electrochemical environments, such as in nanopipets used in SICM, for nanopore measurements, for printing and patterning, and in SECCM, justifying the widespread use of this electrode in the field of nanoelectrochemistry and beyond.
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Affiliation(s)
- Cameron L Bentley
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - David Perry
- 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
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55
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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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56
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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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57
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Bentley CL, Unwin PR. Nanoscale electrochemical movies and synchronous topographical mapping of electrocatalytic materials. Faraday Discuss 2018; 210:365-379. [PMID: 29999075 DOI: 10.1039/c8fd00028j] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Techniques in the scanning electrochemical probe microscopy (SEPM) family have shown great promise for resolving nanoscale structure-function (e.g., catalytic activity) at complex (electro)chemical interfaces, which is a long-term aspiration in (electro)materials science. In this work, we explore how a simple meniscus imaging probe, based on an easily-fabricated, single-channeled nanopipette (inner diameter ≈ 30 nm) can be deployed in the scanning electrochemical cell microscopy (SECCM) platform as a fast, versatile and robust method for the direct, synchronous electrochemical/topographical imaging of electrocatalytic materials at the nanoscale. Topographical and voltammetric data are acquired synchronously at a spatial resolution of 50 nm to construct maps that resolve particular surface features on the sub-10 nm scale and create electrochemical activity movies composed of hundreds of potential-resolved images on the minutes timescale. Using the hydrogen evolution reaction (HER) at molybdenite (MoS2) as an exemplar system, the experimental parameters critical to achieving a robust scanning protocol (e.g., approach voltage, reference potential calibration) with high resolution (e.g., hopping distance) and optimal scan times (e.g., voltammetric scan rate, approach rate etc.) are considered and discussed. Furthermore, sub-nanoentity reactivity mapping is demonstrated with glassy carbon (GC) supported single-crystalline {111}-oriented two-dimensional Au nanocrystals (AuNCs), which exhibit uniform catalytic activity at the single-entity and sub-single entity level. The approach outlined herein signposts a future in (electro)materials science in which the activity of electroactive nanomaterials can be viewed directly and related to structure through electrochemical movies, revealing active sites unambiguously.
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Affiliation(s)
- Cameron L Bentley
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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58
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Izquierdo J, Knittel P, Kranz C. Scanning electrochemical microscopy: an analytical perspective. Anal Bioanal Chem 2017; 410:307-324. [PMID: 29214533 DOI: 10.1007/s00216-017-0742-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/16/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022]
Abstract
Scanning electrochemical microscopy (SECM) has evolved from an electrochemical specialist tool to a broadly used electroanalytical surface technique, which has experienced exciting developments for nanoscale electrochemical studies in recent years. Several companies now offer commercial instruments, and SECM has been used in a broad range of applications. SECM research is frequently interdisciplinary, bridging areas ranging from electrochemistry, nanotechnology, and materials science to biomedical research. Although SECM is considered a modern electroanalytical technique, it appears that less attention is paid to so-called analytical figures of merit, which are essential also in electroanalytical chemistry. Besides instrumental developments, this review focuses on aspects such as reliability, repeatability, and reproducibility of SECM data. The review is intended to spark discussion within the community on this topic, but also to raise awareness of the challenges faced during the evaluation of quantitative SECM data.
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Affiliation(s)
- Javier Izquierdo
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Peter Knittel
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- Fraunhofer Institute for Applied Solid State Physics, Tullastraße 72, 79108, Freiburg, Germany
| | - Christine Kranz
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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59
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Soldà A, Valenti G, Marcaccio M, Giorgio M, Pelicci PG, Paolucci F, Rapino S. Glucose and Lactate Miniaturized Biosensors for SECM-Based High-Spatial Resolution Analysis: A Comparative Study. ACS Sens 2017; 2:1310-1318. [PMID: 28836760 DOI: 10.1021/acssensors.7b00324] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
With the aim of developing miniaturized enzymatic biosensors suitable for in vitro diagnostic applications, such as monitoring of metabolites at single cell level, glucose and lactate biosensors were fabricated by immobilizing enzymes (glucose oxidase and lactate oxidase, respectively) on 10 μm Pt ultramicroelectrodes. These electrodes are meant to be employed as probes for scanning electrochemical microscopy (SECM), which is a unique technique for high-spatial-resolution electrochemical-based analysis. The use of enzymatic moieties improves sensitivity, time scale response, and information content of the microprobes; however, protein immobilization is a key step in the biosensor preparation that greatly affects the overall performance. A crucial aspect is the miniaturization of the sensing, preserving their sensitivity. In this work, we investigated the most common enzyme immobilization techniques. Several fabrication routes are reported and the main figures of merit, such as sensitivity, detection limit, response time, reproducibility, spatial resolution, biosensor efficiency, permeability, selectivity, and the ability to block electro-active interfering species, are investigated and compared. With the intent of using the microprobes for in vitro functional imaging of single living cells, we carefully evaluate the spatial resolution achieved by our modified electrodes on 2D SECM imaging. Metabolic activity of single MCF10A cells were obtained by monitoring the glucose concentrations in close proximity of single living cell, using the UME-based biosensor probes prepared. A voltage-switch approach was implemented to disentangle the topographical contribution of the cells enabling quantitative measurements of cellular uptakes.
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Affiliation(s)
- Alice Soldà
- Chemistry
Department “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
- Experimental
Oncology Department, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Giovanni Valenti
- Chemistry
Department “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Massimo Marcaccio
- Chemistry
Department “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Marco Giorgio
- Experimental
Oncology Department, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Pier Giuseppe Pelicci
- Experimental
Oncology Department, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Francesco Paolucci
- Chemistry
Department “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Stefania Rapino
- Chemistry
Department “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
- Experimental
Oncology Department, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
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60
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Bentley CL, Kang M, Maddar FM, Li F, Walker M, Zhang J, Unwin PR. Electrochemical maps and movies of the hydrogen evolution reaction on natural crystals of molybdenite (MoS 2): basal vs. edge plane activity. Chem Sci 2017; 8:6583-6593. [PMID: 28989686 PMCID: PMC5627349 DOI: 10.1039/c7sc02545a] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/25/2017] [Indexed: 12/23/2022] Open
Abstract
Two dimensional (2D) semiconductor materials, such as molybdenum disulfide (MoS2) have attracted considerable interest in a range of chemical and electrochemical applications, for example, as an abundant and low-cost alternative electrocatalyst to platinum for the hydrogen evolution reaction (HER). While it has been proposed that the edge plane of MoS2 possesses high catalytic activity for the HER relative to the "catalytically inert" basal plane, this conclusion has been drawn mainly from macroscale electrochemical (voltammetric) measurements, which reflect the "average" electrocatalytic behavior of complex electrode ensembles. In this work, we report the first spatially-resolved measurements of HER activity on natural crystals of molybdenite, achieved using voltammetric scanning electrochemical cell microscopy (SECCM), whereby pixel-resolved linear-sweep voltammogram (LSV) measurements have allowed the HER to be visualized at multiple different potentials to construct electrochemical flux movies with nanoscale resolution. Key features of the SECCM technique are that characteristic surface sites can be targeted and analyzed in detail and, further, that the electrocatalyst area is known with good precision (in contrast to many macroscale measurements on supported catalysts). Through correlation of the local voltammetric response with information from scanning electron microscopy (SEM) and atomic force microscopy (AFM) in a multi-microscopy approach, it is demonstrated unequivocally that while the basal plane of bulk MoS2 (2H crystal phase) possesses significant activity, the HER is greatly facilitated at the edge plane (e.g., surface defects such as steps, edges or crevices). Semi-quantitative treatment of the voltammetric data reveals that the HER at the basal plane of MoS2 has a Tafel slope and exchange current density (J0) of ∼120 mV per decade and 2.5 × 10-6 A cm-2 (comparable to polycrystalline Co, Ni, Cu and Au), respectively, while the edge plane has a comparable Tafel slope and a J0 that is estimated to be more than an order-of-magnitude larger (∼1 × 10-4 A cm-2). Finally, by tracking the temporal evolution of water contact angle (WCA) after cleavage, it is shown that cathodic polarization has a 'self-cleaning' effect on the surface of MoS2, consistent with the time-independent (i.e., time after cleavage) HER voltammetric response.
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Affiliation(s)
- Cameron L Bentley
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , UK . ;
| | - Minkyung Kang
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , UK . ;
| | - Faduma M Maddar
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , UK . ;
| | - Fengwang Li
- School of Chemistry , Australian Research Council Centre of Excellence for Electromaterials Science , Monash University , Clayton , Vic 3800 , Australia
| | - Marc Walker
- Department of Physics , University of Warwick , Coventry CV4 7AL , UK
| | - Jie Zhang
- School of Chemistry , Australian Research Council Centre of Excellence for Electromaterials Science , Monash University , Clayton , Vic 3800 , Australia
| | - Patrick R Unwin
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , UK . ;
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61
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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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62
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Arcadia CE, Reyes CC, Rosenstein JK. In Situ Nanopore Fabrication and Single-Molecule Sensing with Microscale Liquid Contacts. ACS NANO 2017; 11:4907-4915. [PMID: 28485922 DOI: 10.1021/acsnano.7b01519] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In this article, we introduce a flexible technique for high-throughput solid-state nanopore analysis of single biomolecules. By confining the electrolyte to a micron-scale liquid meniscus at the tip of a glass micropipette, we enable automation and reuse of a single solid-state membrane chip for measurements with hundreds of distinct nanopores per day. In addition to overcoming important experimental bottlenecks, the microscale liquid contact dramatically reduces device capacitance, which is a key limiting factor to the speed and fidelity of solid-state nanopore sensor recordings.
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Affiliation(s)
- Christopher E Arcadia
- School of Engineering, Brown University , Providence, Rhode Island 02912, United States
| | - Carlos C Reyes
- School of Engineering, Brown University , Providence, Rhode Island 02912, United States
| | - Jacob K Rosenstein
- School of Engineering, Brown University , Providence, Rhode Island 02912, United States
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63
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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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64
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Saha-Shah A, Green CM, Abraham DH, Baker LA. Segmented flow sampling with push-pull theta pipettes. Analyst 2017; 141:1958-65. [PMID: 26907673 DOI: 10.1039/c6an00028b] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We report development of a mobile and easy-to-fabricate theta pipette microfluidic device for segmented flow sampling. The theta pipettes were also used as electrospray emitters for analysis of sub-nanoliter segments, which resulted in delivery of analyte to the vacuum inlet of the mass spectrometer without multiple transfer steps. Theta pipette probes enable sample collection with high spatial resolution due to micron or smaller sized probe inlets and can be used to manipulate aqueous segments in the range of 200 pL to tens of nanoliters. Optimized conditions can enable sampling with high spatial and temporal resolution, suitable for chemical monitoring in biological samples and studies of sample heterogeneity. Intercellular heterogeneity among Allium cepa cells was studied by collecting cytoplasm from multiple cells using a single probe. Extracted cytoplasm was analyzed in a fast and high throughput manner by direct electrospray mass spectrometry of segmented sample from the probe tip.
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Affiliation(s)
- Anumita Saha-Shah
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA.
| | - Curtis M Green
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA.
| | - David H Abraham
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA.
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA.
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65
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MATSUOKA R, AOYAGI S, MATSUMOTO N, MATSUDAIRA M, TAKAHASHI Y, KUMATANI A, IDA H, MUNAKATA H, IIDA K, SHIKU H, KANAMURA K, MATSUE T. Advanced Scanning Electrochemical Microscope System for High-Resolution imaging and Electrochemical Applications. ELECTROCHEMISTRY 2017. [DOI: 10.5796/electrochemistry.85.319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
| | | | | | | | - Yasufumi TAKAHASHI
- Division of Electrical and Computer Engineering, Kanazawa University
- PRESTO, JST
| | - Akichika KUMATANI
- Graduate School of Environmental Stadies, Tohoku University
- WPI-Advanced Institute for Materials Research, Tohoku University
| | - Hiroki IDA
- Graduate School of Environmental Stadies, Tohoku University
| | - Hirokazu MUNAKATA
- Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University
| | | | | | - Kiyoshi KANAMURA
- Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University
| | - Tomokazu MATSUE
- Graduate School of Environmental Stadies, Tohoku University
- WPI-Advanced Institute for Materials Research, Tohoku University
- Graduate School of Engineering, Tohoku University
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66
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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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67
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Gold nanoparticle mediated method for spatially resolved deposition of DNA on nano-gapped interdigitated electrodes, and its application to the detection of the human Papillomavirus. Mikrochim Acta 2016. [DOI: 10.1007/s00604-016-1954-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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68
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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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69
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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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70
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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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71
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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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73
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74
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Momotenko D, McKelvey K, Kang M, Meloni GN, Unwin PR. Simultaneous Interfacial Reactivity and Topography Mapping with Scanning Ion Conductance Microscopy. Anal Chem 2016; 88:2838-46. [DOI: 10.1021/acs.analchem.5b04566] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Dmitry Momotenko
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Kim McKelvey
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Minkyung Kang
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Gabriel N. Meloni
- 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
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75
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TAKAHASHI Y. Development of High-Resolution Scanning Electrochemical Microscopy for Nanoscale Topography and Electrochemical Simultaneous Imaging. ELECTROCHEMISTRY 2016. [DOI: 10.5796/electrochemistry.84.662] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Yasufumi TAKAHASHI
- Division of Electrical Engineering and Computer Science, Kanazawa University
- PRESTO, JST
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76
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Zhang G, Tan SY, Patel AN, Unwin PR. Electrochemistry of Fe3+/2+ at highly oriented pyrolytic graphite (HOPG) electrodes: kinetics, identification of major electroactive sites and time effects on the response. Phys Chem Chem Phys 2016; 18:32387-32395. [DOI: 10.1039/c6cp06472h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Electron transfer kinetics of Fe3+/2+ on HOPG is as fast as on metals, with the electroactivity dominated by basal plane.
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Affiliation(s)
- Guohui Zhang
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
| | - Sze-yin Tan
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
| | - Anisha N. Patel
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
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77
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Maddar FM, Lazenby RA, Patel AN, Unwin PR. Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH): comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes. Phys Chem Chem Phys 2016; 18:26404-26411. [DOI: 10.1039/c6cp05394g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
NADH electro-oxidation is faster, but more prone to fouling, at HOPG compared to pBDD.
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Affiliation(s)
| | | | - Anisha N. Patel
- Department of Chemistry
- University of Warwick
- Coventry
- UK
- Interfaces, Traitements, Organisation et Dynamique des Systèmes Laboratory
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78
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Yuill EM, Shi W, Poehlman J, Baker LA. Scanning Electrospray Microscopy with Nanopipets. Anal Chem 2015; 87:11182-6. [DOI: 10.1021/acs.analchem.5b03399] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Elizabeth M. Yuill
- Department of Chemistry, Indiana University, 800 E. Kirkwood
Avenue, Bloomington, Indiana 47405, United States
| | - Wenqing Shi
- Department of Chemistry, Indiana University, 800 E. Kirkwood
Avenue, Bloomington, Indiana 47405, United States
| | - John Poehlman
- Department of Chemistry, Indiana University, 800 E. Kirkwood
Avenue, Bloomington, Indiana 47405, United States
| | - Lane A. Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood
Avenue, Bloomington, Indiana 47405, United States
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79
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Zhou M, Yu Y, Blanchard PY, Mirkin MV. Surface Patterning Using Diazonium Ink Filled Nanopipette. Anal Chem 2015; 87:10956-62. [DOI: 10.1021/acs.analchem.5b02784] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Min Zhou
- Department
of Chemistry and Biochemistry, Queens College, CUNY, Flushing, New York 11367, United States
- The Graduate Center of CUNY, New York, New York 10016, United States
| | - Yun Yu
- Department
of Chemistry and Biochemistry, Queens College, CUNY, Flushing, New York 11367, United States
- The Graduate Center of CUNY, New York, New York 10016, United States
| | - Pierre-Yves Blanchard
- Department
of Chemistry and Biochemistry, Queens College, CUNY, 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, CUNY, Flushing, New York 11367, United States
- The Graduate Center of CUNY, New York, New York 10016, United States
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80
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Holzinger A, Steinbach C, Kranz C. Scanning Electrochemical Microscopy (SECM): Fundamentals and Applications in Life Sciences. ELECTROCHEMICAL STRATEGIES IN DETECTION SCIENCE 2015. [DOI: 10.1039/9781782622529-00125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In recent years, scanning electrochemical microscopy (SECM) has made significant contributions to the life sciences. Innovative developments focusing on high-resolution imaging, developing novel operation modes, and combining SECM with complementary optical or scanning probe techniques renders SECM an attractive analytical approach. This chapter gives an introduction to the essential instrumentation and operation principles of SECM for studying biologically-relevant systems. Particular emphasis is given to applications aimed at imaging the activity of biochemical constituents such as enzymes, antibodies, and DNA, which play a pivotal role in biomedical diagnostics. Furthermore, the unique advantages of SECM and combined techniques for studying live cells is highlighted by discussion of selected examples.
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Affiliation(s)
- Angelika Holzinger
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm 89069 Ulm Germany
| | - Charlotte Steinbach
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm 89069 Ulm Germany
| | - Christine Kranz
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm 89069 Ulm Germany
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81
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Guo X, Zhou H, Zhang D, Fan T. Cyclic voltammogram on ridge/pore array architectured electrode inspired by butterfly-wings. PURE APPL CHEM 2015. [DOI: 10.1515/pac-2014-1201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractPorous architectured electrodes are intensely investigated for promoting electrochemical performance. Besides the high surface area, mass transport plays an irreplaceable role in the architecture assisting effect, which is, however, far beyond expression due to the complexity and irregularity of various electrode materials. Here, we took advantage of elaborate architectures from butterfly wings and obtained carbon electrode with ridge/pore array hierarchical architecture (ridge/pore-C) using a carbonizing-graphite coating method. A basic one-electron transfer process using the redox couple ferri/ferrocyanide as a benchmark under cyclic voltammetric conditions was conducted. The peak potential separation for ridge/pore-C was decreased by 117 mV compared to its non-architectured counterpart, with obvious enhancement of peak current density, indicating prominent beneficial impact on electrochemical responses. Further finite element simulation demonstrated the additional lateral diffusion within the ridge domain and partial thin layer diffusion within the pore array domain of ridge/pore-C, and simultaneously verified the experimental results. By constructing and investigating the well-organized porous architecture for affecting cyclic voltammogram, this work provides a prototype and cost-effective method for structural design of efficient electrodes by drawing inspiration from nature.
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Affiliation(s)
- Xingmei Guo
- 1State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Han Zhou
- 1State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Di Zhang
- 1State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Tongxiang Fan
- 1State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
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82
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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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83
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Güell AG, Cuharuc AS, Kim YR, Zhang G, Tan SY, Ebejer N, Unwin PR. Redox-dependent spatially resolved electrochemistry at graphene and graphite step edges. ACS NANO 2015; 9:3558-71. [PMID: 25758160 DOI: 10.1021/acsnano.5b00550] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The electrochemical (EC) behavior of mechanically exfoliated graphene and highly oriented pyrolytic graphite (HOPG) is studied at high spatial resolution in aqueous solutions using Ru(NH3)6(3+/2+) as a redox probe whose standard potential sits close to the intrinsic Fermi level of graphene and graphite. When scanning electrochemical cell microscopy (SECCM) data are coupled with that from complementary techniques (AFM, micro-Raman) applied to the same sample area, different time-dependent EC activity between the basal planes and step edges is revealed. In contrast, other redox couples (ferrocene derivatives) whose potential is further removed from the intrinsic Fermi level of graphene and graphite show uniform and high activity (close to diffusion-control). Macroscopic voltammetric measurements in different environments reveal that the time-dependent behavior after HOPG cleavage, peculiar to Ru(NH3)6(3+/2+), is not associated particularly with any surface contaminants but is reasonably attributed to the spontaneous delamination of the HOPG with time to create partially coupled graphene layers, further supported by conductive AFM measurements. This process has a major impact on the density of states of graphene and graphite edges, particularly at the intrinsic Fermi level to which Ru(NH3)6(3+/2+) is most sensitive. Through the use of an improved voltammetric mode of SECCM, we produce movies of potential-resolved and spatially resolved HOPG activity, revealing how enhanced activity at step edges is a subtle effect for Ru(NH3)6(3+/2+). These latter studies allow us to propose a microscopic model to interpret the EC response of graphene (basal plane and edges) and aged HOPG considering the nontrivial electronic band structure.
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Affiliation(s)
- Aleix G Güell
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Anatolii S Cuharuc
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Yang-Rae Kim
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Guohui Zhang
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Sze-yin Tan
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Neil Ebejer
- 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
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84
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Bandarenka AS, Ventosa E, Maljusch A, Masa J, Schuhmann W. Techniques and methodologies in modern electrocatalysis: evaluation of activity, selectivity and stability of catalytic materials. Analyst 2015; 139:1274-91. [PMID: 24418971 DOI: 10.1039/c3an01647a] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development and optimisation of materials that promote electrochemical reactions have recently attracted attention mainly due to the challenge of sustainable provision of renewable energy in the future. The need for better understanding and control of electrode-electrolyte interfaces where these reactions take place, however, implies the continuous need for development of efficient analytical techniques and methodologies capable of providing detailed information about the performance of electrocatalysts, especially in situ, under real operational conditions of electrochemical systems. During the past decade, significant efforts in the fields of electrocatalysis and (electro)analytical chemistry have resulted in the evolution of new powerful methods and approaches providing ever deeper and unique insight into complex and dynamic catalytic systems. The combination of various electrochemical and non-electrochemical methods as well as the application of quantum chemistry calculations has become a viable modern approach in the field. The focus of this critical review is primarily set on discussion of the most recent cutting-edge achievements in the development of analytical techniques and methodologies designed to evaluate three key constituents of the performance of electrocatalysts, namely, activity, selectivity and stability. Possible directions and future challenges in the design and elaboration of analytical methods for electrocatalytic research are outlined.
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Affiliation(s)
- Aliaksandr S Bandarenka
- Center for Electrochemical Sciences - CES, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
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85
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Aaronson BDB, Byers JC, Colburn AW, McKelvey K, Unwin PR. Scanning Electrochemical Cell Microscopy Platform for Ultrasensitive Photoelectrochemical Imaging. Anal Chem 2015; 87:4129-33. [DOI: 10.1021/acs.analchem.5b00288] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Barak D. B. Aaronson
- Department
of Chemistry, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL United Kingdom
| | - Joshua C. Byers
- Department
of Chemistry, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL United Kingdom
| | - Alex W. Colburn
- Department
of Chemistry, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL United Kingdom
| | - Kim McKelvey
- Department
of Chemistry, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL United Kingdom
| | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL United Kingdom
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86
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Nadappuram BP, McKelvey K, Byers JC, Güell AG, Colburn AW, Lazenby RA, Unwin PR. Quad-barrel multifunctional electrochemical and ion conductance probe for voltammetric analysis and imaging. Anal Chem 2015; 87:3566-73. [PMID: 25719392 DOI: 10.1021/acs.analchem.5b00379] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The fabrication and use of a multifunctional electrochemical probe incorporating two independent carbon working electrodes and two electrolyte-filled barrels, equipped with quasi-reference counter electrodes (QRCEs), in the end of a tapered micrometer-scale pipet is described. This "quad-probe" (4-channel probe) was fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barrelled pipet. After filling the open channels with electrolyte solution, a meniscus forms at the end of the probe and covers the two working electrodes. The two carbon electrodes can be used to drive local electrochemical reactions within the meniscus while a bias between the QRCEs in the electrolyte channels provides an ion conductance signal that is used to control and position the meniscus on a surface of interest. When brought into contact with a surface, localized high resolution amperometric imaging can be achieved with the two carbon working electrodes with a spatial resolution defined by the meniscus contact area. The substrate can be an insulating material or (semi)conductor, but herein, we focus mainly on conducting substrates that can be connected as a third working electrode. Studies using both aqueous and ionic liquid electrolytes in the probe, together with gold and individual single walled carbon nanotube samples, demonstrate the utility of the technique. Substrate generation-dual tip collection measurements are shown to be characterized by high collection efficiencies (approaching 100%). This hybrid configuration of scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM) should be powerful for future applications in electrode mapping, as well as in studies of insulating materials as demonstrated by transient spot redox-titration measurements at an electrostatically charged Teflon surface and at a pristine calcite surface, where a functionalized probe is used to follow the immediate pH change due to dissolution.
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Affiliation(s)
| | - Kim McKelvey
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Joshua C Byers
- 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
| | - Alex W Colburn
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Robert A Lazenby
- 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
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87
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Lai SCS, Lazenby RA, Kirkman PM, Unwin PR. Nucleation, aggregative growth and detachment of metal nanoparticles during electrodeposition at electrode surfaces. Chem Sci 2015; 6:1126-1138. [PMID: 29560200 PMCID: PMC5811076 DOI: 10.1039/c4sc02792b] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 11/07/2014] [Indexed: 02/01/2023] Open
Abstract
The nucleation and growth of metal nanoparticles (NPs) on surfaces is of considerable interest with regard to creating functional interfaces with myriad applications. Yet, key features of these processes remain elusive and are undergoing revision. Here, the mechanism of the electrodeposition of silver on basal plane highly oriented pyrolytic graphite (HOPG) is investigated as a model system at a wide range of length scales, spanning electrochemical measurements from the macroscale to the nanoscale using scanning electrochemical cell microscopy (SECCM), a pipette-based approach. The macroscale measurements show that the nucleation process cannot be modelled as either truly instantaneous or progressive, and that step edge sites of HOPG do not play a dominant role in nucleation events compared to the HOPG basal plane, as has been widely proposed. Moreover, nucleation numbers extracted from electrochemical analysis do not match those determined by atomic force microscopy (AFM). The high time and spatial resolution of the nanoscale pipette set-up reveals individual nucleation and growth events at the graphite basal surface that are resolved and analysed in detail. Based on these results, corroborated with complementary microscopy measurements, we propose that a nucleation-aggregative growth-detachment mechanism is an important feature of the electrodeposition of silver NPs on HOPG. These findings have major implications for NP electrodeposition and for understanding electrochemical processes at graphitic materials generally.
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Affiliation(s)
- Stanley C S Lai
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , UK .
- MESA+ Institute for Nanotechnology , University of Twente , PO Box 217 , 7500 AE Enschede , The Netherlands .
| | - Robert A Lazenby
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , UK .
| | - Paul M Kirkman
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , UK .
| | - Patrick R Unwin
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , UK .
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88
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Kang H, Hwang S, Kwak J. A hydrogel pen for electrochemical reaction and its applications for 3D printing. NANOSCALE 2015; 7:994-1001. [PMID: 25469501 DOI: 10.1039/c4nr06041e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A hydrogel pen consisting of a microscopic pyramid containing an electrolyte offers a localized electroactive area on the nanometer scale via controlled contact of the apex with a working electrode. The hydrogel pen merges the fine control of atomic force microscopy with non-linear diffusion of an ultramicroelectrode, producing a faradaic current that depends on the small electroactive area. The theoretical and experimental investigations of the mass transport behavior within the hydrogel reveal that the steady-state current from the faradaic reaction is linearly proportional to the deformed length of the hydrogel pen by contact, i.e. signal transduction of deformation to an electrochemical signal, which enables the fine control of the electroactive area in the nanometer-scale regime. Combined with electrodeposition, localized electrochemistry of the hydrogel pen results in the ability to fabricate small sizes (110 nm in diameter), tall heights (up to 30 μm), and arbitrary structures, thereby indicating an additive process in 3 dimensions by localized electrodeposition.
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Affiliation(s)
- Hosuk Kang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.
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89
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Zhang G, Cuharuc AS, Güell AG, Unwin PR. Electrochemistry at highly oriented pyrolytic graphite (HOPG): lower limit for the kinetics of outer-sphere redox processes and general implications for electron transfer models. Phys Chem Chem Phys 2015; 17:11827-38. [DOI: 10.1039/c5cp00383k] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron transfer kinetics for outer-sphere redox couples is fast on the basal surface of highly oriented pyrolytic graphite (HOPG).
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Affiliation(s)
- Guohui Zhang
- Department of Chemistry
- University of Warwick
- Coventry
- UK
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90
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Takahashi Y, Kumatani A, Munakata H, Inomata H, Ito K, Ino K, Shiku H, Unwin PR, Korchev YE, Kanamura K, Matsue T. Nanoscale visualization of redox activity at lithium-ion battery cathodes. Nat Commun 2014; 5:5450. [DOI: 10.1038/ncomms6450] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 10/02/2014] [Indexed: 01/27/2023] Open
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91
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Meadows KE, Nadappuram BP, Unwin PR. A new approach for the fabrication of microscale lipid bilayers at glass pipets: application to quantitative passive permeation visualization. SOFT MATTER 2014; 10:8433-8441. [PMID: 25221789 DOI: 10.1039/c3sm51406d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A new method of planar bilayer lipid membrane (BLM) formation is presented that allows stable, solvent-free lipid bilayers exhibiting high seal resistances to be formed rapidly, easily and reproducibly. Using these bilayers the passive permeation of a series of carboxylic acids is investigated, to determine quantitatively the trend in permeability with lipophilicity of the acid. BLMs are formed at the tip openings of pulled theta pipets, and the rate of permeation of each carboxylic acid across the bilayer, from within the pipet into the bulk solution is determined. This is achieved through spatially-resolved measurements of the pH change that occurs upon the permeation of the weak acid, visualized using a pH-sensitive fluorophore with a confocal laser scanning microscope. The extracted fluorescence profiles are matched to finite element method (FEM) simulations, to allow the associated permeation coefficient for each weak acid to be determined with high accuracy, since this is the only adjustable parameter used to fit the experimental data. For bilayers formed in this way, the weak acids show increasing permeability with lipophilicity. Furthermore, the arrangement allows the effect of a trans-membrane electric field on permeation to be explored. For both propanoic and hexanoic acid it is found that an applied electric field enhances molecular transport, which is attributed to the formation of pores within the membrane.
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92
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Dual-electrode measurements in a meniscus microcapillary electrochemical cell using a high aspect ratio carbon fibre ultramicroelectrode. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2014.06.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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93
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Zhang G, Kirkman PM, Patel AN, Cuharuc AS, McKelvey K, Unwin PR. Molecular Functionalization of Graphite Surfaces: Basal Plane versus Step Edge Electrochemical Activity. J Am Chem Soc 2014; 136:11444-51. [DOI: 10.1021/ja505266d] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Guohui Zhang
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Paul M. Kirkman
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Anisha N. Patel
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Anatolii S. Cuharuc
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Kim McKelvey
- 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
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94
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Kleijn SEF, Lai SCS, Koper MTM, Unwin PR. Electrochemistry of Nanoparticles. Angew Chem Int Ed Engl 2014; 53:3558-86. [DOI: 10.1002/anie.201306828] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Indexed: 01/01/2023]
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95
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96
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Kranz C. Recent advancements in nanoelectrodes and nanopipettes used in combined scanning electrochemical microscopy techniques. Analyst 2014; 139:336-52. [DOI: 10.1039/c3an01651j] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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97
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Toth PS, Valota AT, Velický M, Kinloch IA, Novoselov KS, Hill EW, Dryfe RAW. Electrochemistry in a drop: a study of the electrochemical behaviour of mechanically exfoliated graphene on photoresist coated silicon substrate. Chem Sci 2014. [DOI: 10.1039/c3sc52026a] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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98
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Patel AN, Tan SY, Miller TS, Macpherson JV, Unwin PR. Comparison and Reappraisal of Carbon Electrodes for the Voltammetric Detection of Dopamine. Anal Chem 2013; 85:11755-64. [DOI: 10.1021/ac401969q] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Anisha N. Patel
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Sze-yin Tan
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Thomas S. Miller
- 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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99
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Battistel D, Pecchielan G, Daniele S. Micropipette Contact Technique as a Tool to Reveal, Characterize, and Modify Nanopore Electrodes. ChemElectroChem 2013. [DOI: 10.1002/celc.201300147] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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100
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