New-type electrochemical oscillation caused by electrode - Surface inhomogeneity and electrical coupling as well as solution stirring through electrochemical gas evolution reaction

Citation
Y. Mukouyama et al., New-type electrochemical oscillation caused by electrode - Surface inhomogeneity and electrical coupling as well as solution stirring through electrochemical gas evolution reaction, J PHYS CH B, 105(44), 2001, pp. 10905-10911
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
105
Issue
44
Year of publication
2001
Pages
10905 - 10911
Database
ISI
SICI code
1520-6106(20011108)105:44<10905:NEOCBE>2.0.ZU;2-N
Abstract
The appearance mechanism of an electrochemical oscillation (previously call ed oscillation B), observed for Pt electrodes in H2O2-containing acidic ele ctrolytes in a potential region of hydrogen evolution, has been investigate d. Though it is reported that electrochemical oscillations in general appea r in potential regions of negative differential resistance (NDR) or hidden NDR (HNDR), impedance analyses have shown that no NDR or HNDR is present in the potential region of oscillation B. Besides, oscillation B is observed only for Pt electrodes with atomically roughened surfaces, not for electrod es with atomically flat surfaces. A possible explanation is proposed by ass uming the presence of small local "active" areas in the electrode surface, in which the H2O2 reduction is not prevented by a full coverage of under-po tential deposited hydrogen, contrary to the other normal "nonactive" areas occupying the major part of the electrode surface. The appearance of oscill ation B is reproduced by mathematical simulation based on the model, togeth er with the consideration of electrical coupling between the active and non active areas as well as solution stirring by hydrogen-gas evolution. Oscill ation B can be classified into a new category of oscillators, which may be called "coupled NDR" oscillators.