An electrochemical oscillator: the mercury / chloropentammine cobalt(III) oscillator

Schlegel, James M.; Paretti, Robert F.

doi:10.1016/0022-0728(92)80232-s

Cited by 5 publications

(1 citation statement)

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“…In the next example, the open circuit potential of a HMDE in an aqueous solution containing a complex cobalt ion: Co(NH 3 ) 5 Cl 2þ was reported. These phenomena were interpreted in terms of response of Hg electrode to cyclic changes of pH near the electrode [94].…”

Section: The Mathematical Model Of the "Inhibitor Oscillator"mentioning

confidence: 99%

Temporal Instabilities in Cathodic Processes at Liquid and Solid Electrodes

Orlik

2012

Monographs in Electrochemistry

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In this chapter, examples of temporal instabilities (oscillations and multistability) reported for cathodic processes carried out at both liquid and solid electrodes are described. With respect to liquid ones, the oscillations of the current associated with the electrode processes occurring at mercury have been quite intensively studied for several decades, especially when classical polarography was still the most popular experimental technique in electrochemistry. Therefore, studies of polarographic oscillations greatly contributed to the understanding of the mechanisms of electrochemical oscillations. A big advantage of mercury electrode is its smooth, uniform, and easily renewable surface and a high overvoltage for hydrogen evolution at negative potentials. The structure of the mercury-liquid electrolyte solution is thus much easier to define than, e.g., the structure of the passive layer on corroding solid electrodes. Hence, not only the general source of instability, but also a more detailed (electro)chemical mechanism of oscillations or multistability can be suggested. Based on the characteristics of the polarographic systems one can excellently show the different origins of the negative differential resistance in electrode processes: the potential-dependent repulsion of charged reactant particles from the reaction site in the double layer, the adsorption of an inhibitor of a charge-transfer process, or the desorption of a catalyst of this process (see Sect. 2.1.4). Such studies were later extended for solid electrodes, provided that the region of potential corresponding to instabilities was positive enough to avoid hydrogen evolution. One of the model electrode reactions that served for numerous studies of mechanisms and bifurcation scenarios of dynamic instabilities was the electroreduction of S 2 O 8 2À ions in which the negative differential resistance (N-NDR region) was caused by repulsive interaction of these anions with negatively charged electrode surface. This Frumkin effect was first reported as early as 1933 [1]. In order to understand the detailed origin of this effect, one has to take into account the spatial distribution of the electric potential in the double M. Orlik, Self-Organization in Electrochemical Systems I, Monographs in Electrochemistry,

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Section: The Mathematical Model Of the "Inhibitor Oscillator"mentioning

confidence: 99%