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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Stabilizing Nonstationary Electrochemical Time Series

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Nagao, Raphael [1] ; Sitta, Elton [1] ; Varela, Hamilton [1, 2, 3]
Total Authors: 3
[1] Univ Sao Paulo, Inst Chem Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
[2] GIST, Ertl Ctr Electrochem & Catalysis, Kwangju 500712 - South Korea
[3] Univ Sao Paulo, Inst Adv Studies, BR-05508970 Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry C; v. 114, n. 50, p. 22262-22268, DEC 23 2010.
Web of Science Citations: 32

Electrochemical systems are ideal working-horses for studying oscillatory dynamics. Experimentally obtained time series, however, are usually associated with a spontaneous drift in some uncontrollable parameter that triggers transitions among different oscillatory patterns, despite the fact that all controllable parameters are kept constant. Herein we present an empirical method to stabilize experimental potential time series. The method consists of applying a negative galvanodynamic sweep to compensate the spontaneous drift and was tested for the oscillatory electro-oxidation of methanol on platinum. For a wide range of applied currents, the base system presents spontaneous transitions from quasi-harmonic to mixed mode oscillations. Temporal patterns were stabilized by galvanodynamic sweeps at different rates. The procedure resulted in a considerable increase in the number of oscillatory cycles from 5 to 20 times, depending on the specific temporal pattern. The spontaneous drift has been associated with uncompensated oscillations, in which the coverage of some adsorbed species are not reestablished after one cycle; i.e., there is a net accumulation and/or depletion of adsorbed species during oscillations. We interpreted the rate of the galvanodynamic sweep in terms of the time scales of the poisoning processes that underlies the uncompensated oscillations and thus the spontaneous slow drift. (AU)

FAPESP's process: 09/07629-6 - Electrocatalysis IV: fundamental and applied aspects of electrocatalytic processes, bio-electrocatalysis and kinetic instabilities
Grantee:Edson Antonio Ticianelli
Support type: Program for Research on Bioenergy (BIOEN) - Thematic Grants
FAPESP's process: 09/00153-6 - Spatio-temporal self-organization in electrocatalysis
Grantee:Raphael Nagao de Sousa
Support type: Scholarships in Brazil - Doctorate