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Titolo:
Voltammetric lability of metal complexes at spherical microelectrodes withvarious radii
Autore:
Galceran, J; Puy, J; Salvador, J; Cecilia, J; van Leeuwen, HP;
Indirizzi:
Univ Lleida, Dept Quim, Lleida 25198, Spain Univ Lleida Lleida Spain 25198 iv Lleida, Dept Quim, Lleida 25198, Spain Univ Lleida, Dept Matemat, Lleida 25198, Spain Univ Lleida Lleida Spain 25198 Lleida, Dept Matemat, Lleida 25198, Spain Univ Wageningen & Res Ctr, Lab Phys Chem & Colloid Sci, NL-6703 HB Wageningen, Netherlands Univ Wageningen & Res Ctr Wageningen Netherlands NL-6703HB Netherlands
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 1-2, volume: 505, anno: 2001,
pagine: 85 - 94
Fonte:
ISI
Lingua:
ENG
Soggetto:
ASSOCIATION DISSOCIATION KINETICS; DIFFERENT DIFFUSION-COEFFICIENTS; HOMOGENEOUS CATALYTIC REACTIONS; STEADY-STATE CONDITIONS; ELECTRODE PROCESSES; LIMITING CURRENT; ULTRAMICROELECTRODES; QUASI-1ST; SYSTEMS; MEDIA;
Keywords:
microelectrode; lability; kinetic current; speciation; steady state; reaction layer; CE scheme; pseudo first-order; homogeneous complexation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Galceran, J Univ Lleida, Dept Quim, Rovira Roure 177, Lleida 25198, Spain Univ Lleida Rovira Roure 177 Lleida Spain 25198 25198, Spain
Citazione:
J. Galceran et al., "Voltammetric lability of metal complexes at spherical microelectrodes withvarious radii", J ELEC CHEM, 505(1-2), 2001, pp. 85-94

Abstract

The size of a microelectrode can have a dramatic impact on the relative importance of the diffusional and kinetic contributions to the voltammetric current of an electroactive metal ion in a complexing medium. Decreasing theradius enhances the diffusional contribution and, as a consequence, the complex system tends to move away from labile behaviour (where an equilibriumrelationship holds). Therefore, sufficiently small microelectrodes (eitheror not combined with short measuring times) should be able to sense free metal concentrations directly for not too fast association/dissociation kinetics. The particular case of steady-state spherical (or hemispherical) diffusion under ligand excess (pseudo-first-order kinetics) is solved analytically. The ensuing lability criterion is shown to be in accordance with a geometrical derivation based on an analysis of the random walk of the free metal ions produced by the dissociation of the complex. It is shown that, for a generated metal ion, the probability of reaching the microelectrode surface can be quite different from the planar case. Alternatively, the classical reaction layer concept can be used in the derivation of the lability criterion for spherical geometry as is shown in this work. All treatments show quantitatively how the lability of metal complexes is reduced with decreasing dimension of microelectrode. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 12/12/19 alle ore 10:02:20