The Experts below are selected from a list of 100257 Experts worldwide ranked by ideXlab platform
Patrick R Unwin - One of the best experts on this subject based on the ideXlab platform.
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scanning Electrochemical Cell microscopy seccm chronopotentiometry development and applications in electroanalysis and electrocatalysis
Analytical Chemistry, 2019Co-Authors: Enrico Daviddi, Alex W Colburn, Katerina Gonos, Cameron Luke Bentley, Patrick R UnwinAbstract:Scanning Electrochemical Cell microscopy (SECCM) has been applied for nanoscale (electro)activity mapping in a range of Electrochemical systems but so far has almost exclusively been performed in c...
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scanning Electrochemical Cell microscopy a versatile method for highly localised corrosion related measurements on metal surfaces
Electrochimica Acta, 2019Co-Authors: Lewis C Yule, Cameron Luke Bentley, G D West, Barbara A Shollock, Patrick R UnwinAbstract:Abstract The development of tools that can probe corrosion related phenomena at the (sub)microscale is recognized to be increasingly important in order to understand the surface structural factors (grain orientation, inclusions etc.) that control the (electro)chemical stability (corrosion susceptibility, pitting, passivity etc.) of metal surfaces. Herein we consider the application of scanning Electrochemical Cell microscopy (SECCM), a relatively new member of the Electrochemical droplet Cell (EDC) family, for corrosion research and demonstrate the power of this technique for resolving structure and activity at the (sub)microscale. Hundreds of spatially-resolved (2 μm droplet size) potentiodynamic polarization experiments have been carried out on the several hours timescale and correlated to complementary structural information from electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) in order to determine the effect of grain orientation and inclusions on Electrochemical processes at low carbon steel in neutral solution (10 mM KNO3). Through this approach, it has been shown unequivocally that for the low index planes, anodic currents in the passive region (an indicator of corrosion susceptibility) are greatest on (101) planes compared to (100) and (111) planes. Furthermore, individual sub-micron MnS inclusions have been probed and shown to undergo active dissolution followed by rapid repassivation. This study demonstrates the high versatility of SECCM and the considerable potential of this technique for addressing structure-activity problems in corrosion and electromaterials science.
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voltammetric scanning Electrochemical Cell microscopy dynamic imaging of hydrazine electro oxidation on platinum electrodes
Analytical Chemistry, 2015Co-Authors: Changhui Chen, Kim Mckelvey, Leon Jacobse, Marc T M Koper, Patrick R UnwinAbstract:Voltammetric scanning Electrochemical Cell microscopy (SECCM) incorporates cyclic voltammetry measurements in the SECCM imaging protocol, by recording Electrochemical currents in a wide potential window at each pixel in a map. This provides much more information compared to traditional fixed potential imaging. Data can be represented as movies (hundreds of frames) of current (over a surface region) at a series of potentials and are highly revealing of subtle variations in electrode activity. Furthermore, by combining SECCM data with other forms of microscopy, e.g. scanning electron microscopy and electron backscatter diffraction data, it is possible to directly relate the current–voltage characteristics to spatial position and surface structure. In this work we use a “hopping mode”, where the SECCM pipet probe is translated toward the surface at a series of positions until meniscus contact. Small amounts of residue left on the surface, upon probe retraction, demark the precise area of each measurement. We use these techniques to study hydrazine oxidation on a polycrystalline platinum substrate both in air and in a deaerated environment. In both cases, the detected faradaic current shows a structural dependence on the surface crystallographic orientation. Significantly, in the presence of oxygen (aerated solution) the Electrochemical current decreases strongly for almost all grains (crystallographic orientations). The results highlight the flexibility of voltammetric SECCM for Electrochemical imaging and present important implications for hydrazine electroanalysis.
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scanning Electrochemical Cell microscopy a versatile technique for nanoscale electrochemistry and functional imaging
Reviews in Analytical Chemistry, 2013Co-Authors: Neil Ebejer, Michael E Snowden, Aleix G Guell, Kim Mckelvey, Patrick R UnwinAbstract:Scanning Electrochemical Cell microscopy (SECCM) is a new pipette-based imaging technique purposely designed to allow simultaneous Electrochemical, conductance, and topographical visualization of surfaces and interfaces. SECCM uses a tiny meniscus or droplet, at the end of a double-barreled (theta) pipette, for high-resolution functional imaging and nanoscale Electrochemical measurements. Here we introduce this technique and provide an overview of its principles, instrumentation, and theory. We discuss the power of SECCM in resolving complex structure-activity problems and provide considerable new information on electrode processes by referring to key example systems, including graphene, graphite, carbon nanotubes, nanoparticles, and conducting diamond. The many longstanding questions that SECCM has been able to answer during its short existence demonstrate its potential to become a major technique in electrochemistry and interfacial science.
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scanning Electrochemical Cell microscopy theory and experiment for quantitative high resolution spatially resolved voltammetry and simultaneous ion conductance measurements
Analytical Chemistry, 2012Co-Authors: Michael E Snowden, Aleix G Guell, Kim Mckelvey, Neil Ebejer, Michael A Oconnell, Alex W Colburn, Patrick R UnwinAbstract:Scanning Electrochemical Cell microscopy (SECCM) is a high resolution Electrochemical scanning probe technique that employs a dual-barrel theta pipet probe containing electrolyte solution and quasi-reference counter electrodes (QRCE) in each barrel. A thin layer of electrolyte protruding from the tip of the pipet ensures that a gentle meniscus contact is made with a substrate surface, which defines the active surface area of an Electrochemical Cell. The substrate can be an electrical conductor, semiconductor, or insulator. The main focus here is on the general case where the substrate is a working electrode, and both ion-conductance measurements between the QRCEs in the two barrels and voltammetric/amperometric measurements at the substrate can be made simultaneously. In usual practice, a small perpendicular oscillation of the probe with respect to the substrate is employed, so that an alternating conductance current (ac) develops, due to the change in the dimensions of the electrolyte contact (and hence ...
Md K Nazeeruddin - One of the best experts on this subject based on the ideXlab platform.
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stable single layer light emitting Electrochemical Cell using 4 7 diphenyl 1 10 phenanthroline bis 2 phenylpyridine iridium iii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Enrique Orti, Ruben D Costa, Pedro M Viruela, Md K NazeeruddinAbstract:A significant improvement in the stability of a light emitting Electrochemical Cell was achieved by utilizing a novel iridium(III) complex: 4,7-diphenyl-1,10-phenanthroline-bis(2-phenylpyridine)iridium(III) hexafluorophosphate. The enhanced device stability is correlated by means of DFT studies to be related to a more efficient shielding of the reactive LUMO of the complex.
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efficient and stable solid state light emitting Electrochemical Cell using tris 4 7 diphenyl 1 10 phenanthroline ruthenium ii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Md K NazeeruddinAbstract:The complex tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II), prepared via a simple microwave-assisted synthesis, was used to prepare a single-layer light-emitting Electrochemical Cell. This device reaches a high power efficiency of 1.9 Lum/W at a brightness of 390 cd/m2. Moreover, its lifetime is an order of magnitude longer than that of a similar Cell making use of tris(bipyridine)ruthenium(II) as the emitting complex.
Henk J Bolink - One of the best experts on this subject based on the ideXlab platform.
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near quantitative internal quantum efficiency in a light emitting Electrochemical Cell
Inorganic Chemistry, 2008Co-Authors: Henk J Bolink, Eugenio Coronado, Ruben D Costa, Nora Lardies, Enrique OrtiAbstract:A green-light-emitting iridium(III) complex was prepared that has a photoluminescence quantum yield in a thin-film configuration of almost unity. When used in a simple solid-state single-layer light-emitting Electrochemical Cell, it yielded an external quantum efficiency of nearly 15% and a power efficiency of 38 Lm/W. We argue that these high external efficiencies are only possible if near-quantitative internal electron-to-photon conversion occurs. This shows that the limiting factor for the efficiency of these devices is the photoluminescence quantum yield in a solid film configuration. The observed efficiencies show the prospect of these simple electroluminescent devices for lighting and signage applications.
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stable single layer light emitting Electrochemical Cell using 4 7 diphenyl 1 10 phenanthroline bis 2 phenylpyridine iridium iii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Enrique Orti, Ruben D Costa, Pedro M Viruela, Md K NazeeruddinAbstract:A significant improvement in the stability of a light emitting Electrochemical Cell was achieved by utilizing a novel iridium(III) complex: 4,7-diphenyl-1,10-phenanthroline-bis(2-phenylpyridine)iridium(III) hexafluorophosphate. The enhanced device stability is correlated by means of DFT studies to be related to a more efficient shielding of the reactive LUMO of the complex.
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efficient and stable solid state light emitting Electrochemical Cell using tris 4 7 diphenyl 1 10 phenanthroline ruthenium ii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Md K NazeeruddinAbstract:The complex tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II), prepared via a simple microwave-assisted synthesis, was used to prepare a single-layer light-emitting Electrochemical Cell. This device reaches a high power efficiency of 1.9 Lum/W at a brightness of 390 cd/m2. Moreover, its lifetime is an order of magnitude longer than that of a similar Cell making use of tris(bipyridine)ruthenium(II) as the emitting complex.
Eugenio Coronado - One of the best experts on this subject based on the ideXlab platform.
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near quantitative internal quantum efficiency in a light emitting Electrochemical Cell
Inorganic Chemistry, 2008Co-Authors: Henk J Bolink, Eugenio Coronado, Ruben D Costa, Nora Lardies, Enrique OrtiAbstract:A green-light-emitting iridium(III) complex was prepared that has a photoluminescence quantum yield in a thin-film configuration of almost unity. When used in a simple solid-state single-layer light-emitting Electrochemical Cell, it yielded an external quantum efficiency of nearly 15% and a power efficiency of 38 Lm/W. We argue that these high external efficiencies are only possible if near-quantitative internal electron-to-photon conversion occurs. This shows that the limiting factor for the efficiency of these devices is the photoluminescence quantum yield in a solid film configuration. The observed efficiencies show the prospect of these simple electroluminescent devices for lighting and signage applications.
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stable single layer light emitting Electrochemical Cell using 4 7 diphenyl 1 10 phenanthroline bis 2 phenylpyridine iridium iii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Enrique Orti, Ruben D Costa, Pedro M Viruela, Md K NazeeruddinAbstract:A significant improvement in the stability of a light emitting Electrochemical Cell was achieved by utilizing a novel iridium(III) complex: 4,7-diphenyl-1,10-phenanthroline-bis(2-phenylpyridine)iridium(III) hexafluorophosphate. The enhanced device stability is correlated by means of DFT studies to be related to a more efficient shielding of the reactive LUMO of the complex.
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efficient and stable solid state light emitting Electrochemical Cell using tris 4 7 diphenyl 1 10 phenanthroline ruthenium ii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Md K NazeeruddinAbstract:The complex tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II), prepared via a simple microwave-assisted synthesis, was used to prepare a single-layer light-emitting Electrochemical Cell. This device reaches a high power efficiency of 1.9 Lum/W at a brightness of 390 cd/m2. Moreover, its lifetime is an order of magnitude longer than that of a similar Cell making use of tris(bipyridine)ruthenium(II) as the emitting complex.
Luca Cappelli - One of the best experts on this subject based on the ideXlab platform.
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stable single layer light emitting Electrochemical Cell using 4 7 diphenyl 1 10 phenanthroline bis 2 phenylpyridine iridium iii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Enrique Orti, Ruben D Costa, Pedro M Viruela, Md K NazeeruddinAbstract:A significant improvement in the stability of a light emitting Electrochemical Cell was achieved by utilizing a novel iridium(III) complex: 4,7-diphenyl-1,10-phenanthroline-bis(2-phenylpyridine)iridium(III) hexafluorophosphate. The enhanced device stability is correlated by means of DFT studies to be related to a more efficient shielding of the reactive LUMO of the complex.
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efficient and stable solid state light emitting Electrochemical Cell using tris 4 7 diphenyl 1 10 phenanthroline ruthenium ii hexafluorophosphate
Journal of the American Chemical Society, 2006Co-Authors: Henk J Bolink, Michael Gratzel, Luca Cappelli, Eugenio Coronado, Md K NazeeruddinAbstract:The complex tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II), prepared via a simple microwave-assisted synthesis, was used to prepare a single-layer light-emitting Electrochemical Cell. This device reaches a high power efficiency of 1.9 Lum/W at a brightness of 390 cd/m2. Moreover, its lifetime is an order of magnitude longer than that of a similar Cell making use of tris(bipyridine)ruthenium(II) as the emitting complex.