55:. This ongoing current in both directions is called the exchange current density. When the potential is set more negative than the formal potential, the cathodic current is greater than the anodic current. Written as a reduction, cathodic current is positive. The net current density is the difference between the cathodic and anodic current density.
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The exchange current density is the current in the absence of net electrolysis and at zero overpotential. The exchange current can be thought of as a background current to which the net current observed at various overpotentials is normalized. For a redox reaction written as a reduction at the
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Less important but still relevant are the environment of the solution including the solvent, nature of other electrolytes, and temperature. For the concentration dependence of the exchange current density, the following expression is given for a one-electron reaction:
78:
electrodes for reduction of protons differ by a factor of 10, indicative of the excellent catalytic properties of platinum. Owing to this difference, mercury is the preferred electrode material at reducing (cathodic) potentials in aqueous solution.
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oxides and adsorbed species on the surface, also influence the electron transfer. The nature of the electroactive species (the analyte) in the solution also critically affects the exchange current densities, both the reduced and oxidized form.
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The exchange current density depends critically on the nature of the electrode, not only its structure, but also physical parameters such as surface roughness. Of course, factors that change the composition of the electrode, including
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70:. Such rates provide insights into the structure and bonding in the analyte and the electrode. For example, the exchange current densities for
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equilibrium potential, electron transfer processes continue at electrode/solution interface in both directions. The
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expressions. The Tafel equation describes the dependence of current for an electrolytic process to
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Comparison of exchange current density for proton reduction reaction in 1 mol/kg H
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190:{\displaystyle j_{0}=Fk_{0}(C_{oxy}^{1-\beta }C_{red}^{\beta })}
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Exchange current densities reflect intrinsic rates of
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552:Carl H. Hamann, Andrew Hamnett, Wolf Vielstich,
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532:D. T. Sawyer, A. Sobkowiak, and J. L. Roberts,
83:Parameters affecting exchange current density
236:: the concentration of the oxidized species
271:: the concentration of the reduced species
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556:, 2nd edition: 2, Wiley-VCH, 2007,
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534:Electrochemistry for Chemists
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27:is a parameter used in the
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564:, 9783527310692, page 169
536:, John Wiley, NY, 1995.
344:: reaction rate constant
37:electrochemical kinetics
25:exchange current density
264:{\displaystyle C_{red}}
229:{\displaystyle C_{oxy}}
566:(text at Google books)
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286:{\displaystyle \beta }
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33:Butler–Volmer equation
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337:{\displaystyle k_{0}}
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293:: a symmetry factor
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315:: Faraday constant
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308:{\displaystyle F}
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21:electrochemistry
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29:Tafel equation
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41:overpotential
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90:passivating
62:between an
16:A parameter
518:References
35:and other
487:Manganese
387:Palladium
281:β
180:β
159:β
156:−
68:electrode
589:Category
574:See also
467:Titanium
447:Tungsten
397:Platinum
371:Exchange
72:platinum
66:and the
507:Mercury
477:Cadmium
457:Niobium
417:Iridium
407:Rhodium
381:(A/cm)
375:density
373:current
200:where:
76:mercury
64:analyte
560:
540:
427:Nickel
511:12.3
501:12.0
491:10.9
481:10.8
558:ISBN
538:ISBN
497:Lead
471:8.2
461:6.8
451:5.9
441:5.4
437:Gold
431:5.2
421:3.7
411:3.6
401:3.1
391:3.0
377:-log
74:and
19:In
591::
525:^
379:10
359:SO
43:.
31:,
23:,
361:4
357:2
330:0
326:k
303:F
257:d
254:e
251:r
247:C
222:y
219:x
216:o
212:C
185:)
175:d
172:e
169:r
165:C
153:1
148:y
145:x
142:o
138:C
134:(
129:0
125:k
121:F
118:=
113:0
109:j
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