Potential step chronoamperometry at the wall-jet electrode: experimental

Brett, Christopher M. A.; Brett, Ana Maria C.F. Oliveira; Fisher, Adrian C.; Compton, Richard G.

doi:10.1016/0022-0728(92)80560-q

Cited by 19 publications

(7 citation statements)

References 10 publications

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“…To circumvent these issues, we have constructed a simple, yet effective, walljet electrode . As implied by the nomenclature, this apparatus consists of a planar electrode of known area (wall) and an impinging flow of solution (jet) that provides well-defined hydrodynamics normal to the electrode.…”

Section: Introductionmentioning

confidence: 99%

Walljet Electrochemistry: Quantifying Molecular Transport through Metallopolymeric and Zirconium Phosphonate Assembled Porphyrin Square Thin Films

et al. 2004

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By employing redox-active probes, condensed-phase molecular transport through nanoporous thin films can often be measured electrochemically. Certain kinds of electrode materials (e.g. conductive glass) are difficult to fabricate as rotatable disks or as ultramicroelectrodes-the configurations most often used for electrochemical permeation measurements. These limitations point to the need for a more materials-general measurement method. Herein, we report the application of walljet electrochemistry to the study of molecular transport through model metallopolymeric films on indium tin oxide electrodes. A quantitative expression is presented that describes the transport-limited current at the walljet electrode in terms of mass transport through solution and permeation through the film phase. A comparison of the film permeabilities for a series of redox probes measured using the walljet electrode and a rotating disk electrode establishes the accuracy of the walljet method, while also demonstrating similar precision for the two methods. We apply this technique to a system consisting of zirconium phosphonate assembled films of a porphyrinic molecular square. Transport through films comprising three or more layers is free from significant contributions from pinhole defects. Surprisingly, transport through films of this kind is 2-3 orders of magnitude slower than through films constructed via interfacial polymerization of nearly identical supramolecular square building blocks (Keefe; et al. Adv. Mater. 2003, 15, 1936). The zirconium phosphate assembled films show good size exclusion behavior. The details of the observed dependence of permeation rates on probe molecule size can be rationalized with a model that assumes that the walls of the squares are slightly tilted from a strictly vertical geometry, consistent with atomic force microscopy measurements, and assumes that the individual wall geometries are locked by rigid interlayer linkages.

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Section: Introductionmentioning

confidence: 99%

Walljet Electrochemistry: Quantifying Molecular Transport through Metallopolymeric and Zirconium Phosphonate Assembled Porphyrin Square Thin Films

et al. 2004

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“…where d is the microelectrode diameter (7.0 mm), D the diffusion coef®cient of the electroactive species (6.2Â10 À6 cm 2 s À1 [16]), c I the concentration of electroactive species (2.0Â10 À6 mol cm À3 ), n the number of electrons transferred and F is the Faraday constant, gives a value of 1.68 nA per independent microelectrode. The total currents at low convection rates reach $1.0 mA, which suggests that there are approximately 600 active microdisks.…”

Section: Oxidation Of Hexacyanoferrate(ii)mentioning

confidence: 99%

Microelectrode arrays: application in batch-injection analysis

Fungaro

Brett

1999

Analytica Chimica Acta

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The application of microelectrode arrays in electrochemical batch-injection analysis, injection volumes 100 ml, has been investigated using a random array of microdisks (RAM) electrode made with carbon ®bres. Preliminary batch-injection experiments involving hexacyanoferrate(II) oxidation, using ®xed-potential amperometry and cyclic voltammetry, showed the expected lesser dependence on injection¯ow rate and the steady-state current characteristics of the RAM electrode, compared to results from similar experiments at macroelectrodes. After electrodepositing mercury on the carbon ®bre disks, square wave anodic stripping voltammetry of the test of heavy metals zinc, cadmium and lead was carried out by batch-injection analysis. It was found that the accumulation time of the metals in¯uenced the response to a greater extent than at macroelectrodes, that the in¯uence on the injected volume was similar to that at macroelectrodes and the in¯uence of injection¯ow rate was less. Detection limits are improved at the RAM electrode; sensitivity as a function of normalised electrode area is also enhanced. Experiments in which the RAM electrode was covered by a thin Na®on ®lm before carrying out BIA±SWASV were also performed, and showed similar trends. Although BIA can be performed directly on real samples without added electrolyte, the combination with microelectrodes, which by themselves permit measurements in highly resistive media and fast scan rates, may prove to be very valuable in extreme situations. #

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“…Rotating disk electrochemistry (RDE) is the typical hydrodynamic method used to evaluate interfacial electron transfer rates; however, it is difficult to design RDE electrodes containing conductive ITO glass . Wall-jet electrochemistry offers an alternative forced-convection hydrodynamic method that allows for the use of a wider range of planar electrode materials, including ITO. − …”

Section: Resultsmentioning

confidence: 99%

Electrochemical Rectification of Redox Mediators Using Porphyrin-Based Molecular Multilayered Films on ITO Electrodes

Civic

Dinolfo

2016

ACS Appl. Mater. Interfaces

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Electrochemical charge transfer through multilayer thin films of zinc and nickel 5,10,15,20-tetra(4-ethynylphenyl) porphyrin constructed via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry was examined. Current rectification toward various outer-sphere redox probes is revealed with increasing numbers of layers, as these films possess insulating properties over the neutral potential range of the porphyrin, then become conductive upon reaching its oxidation potential. Interfacial electron transfer rates of mediator-dye interactions toward [Co(bpy)3](2+), [Co(dmb)3](2+), [Co(NO2-phen)3](2+), [Fe(bpy)3](2+), and ferrocene (Fc), all outer-sphere redox species, were measured by hydrodynamic methods. The ability to modify electroactive films' interfacial electron transfer rates, as well as current rectification toward redox species, has broad applicability in a number of devices, particularly photovoltaics and photogalvanics.

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Potential step chronoamperometry at the wall-jet electrode: experimental

Cited by 19 publications

References 10 publications

Walljet Electrochemistry: Quantifying Molecular Transport through Metallopolymeric and Zirconium Phosphonate Assembled Porphyrin Square Thin Films

Walljet Electrochemistry: Quantifying Molecular Transport through Metallopolymeric and Zirconium Phosphonate Assembled Porphyrin Square Thin Films

Microelectrode arrays: application in batch-injection analysis

Electrochemical Rectification of Redox Mediators Using Porphyrin-Based Molecular Multilayered Films on ITO Electrodes

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