Principles of Temporal and Spatial Pattern Formation in Electrochemical Systems

Krischer, Katharina

doi:10.1007/0-306-46916-2_1

Cited by 72 publications

(137 citation statements)

References 150 publications

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“…Once this NDR is not apparent in a stationary current/potential curve, it has been often named hidden NDR or HN-NDR. [42][43][44][45] In this type of electrochemical oscillator the hidden NDR is associated to an N shaped current/potential curve, the electrode potential plays the role of activator and is involved in a positive feedback loop. Important to the present context is that such system is capable to oscillate also under potentiostatic conditions provided that a certain ohmic drop exists in the potentiostaic control circuit.…”

Section: In Situ Ftir Experimentsmentioning

confidence: 99%

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Martins¹,

Batista²,

Sitta³

et al. 2008

J. Braz. Chem. Soc.

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Descreve-se neste artigo a observação experimental de dinâmica oscilatória durante a oxidação eletrocatalítica de metanol sobre platina. Além das, previamente relatadas, oscilações de potencial, oscilações de corrente obtidas sob controle potenciostático também são apresentadas. A região de existência de oscilações de corrente é mapeada no plano de bifurcação voltagem aplicada x resistência. Conjuntamente com investigações eletroquímicas, espectroscopia FTIR in situ também foi aplicada nestes estudos. Apesar de não ter sido possível acompanhar eventuais variações de intermediários reacionais durante as oscilações, tais experimentos revelaram que a cobertura média de monóxido de carbono permanece consideravelmente alta durante as oscilações. Os resultados são discutidos e comparados com as oscilações observadas na eletrooxidação de ácido fórmico, um sistema cujo comportamento é mais entendido e amplamente fundamentado por dados espectroscópicos obtidos in situ.It is described in this paper the experimental observation of oscillatory dynamics during the electrocatalytic oxidation of methanol on platinum. Besides the previously reported potential oscillations, current oscillations obtained under potentiostatic control are also presented. The existence region of current oscillations is mapped in an applied voltage x resistance bifurcation diagram. Conjointly with electrochemical investigations, in situ FTIR spectroscopy was also employed in the present studies. Although we were not able to follow eventual intermediate coverage changes during the oscillations, those experiments revealled that the mean coverage of adsorbed carbon monoxide remains appreciably high along the oscillations. Results are discussed and compared with the oscillations observed in the electrooxidation of formic acid, a system whose behavior is more understood and widely supported by in situ spectroscopic data. Keywords: current and potential oscillations, methanol, electrocatalysis, in situ FTIR IntroductionMethanol has been pointed as one of the most promising organic molecules to be used in large scale energy conversion systems, as in the so-called direct methanol fuel cells (DMFC). [1][2][3] Limitations associated to the high overpotential and the existence of parallel reaction pathways makes its understanding a rather challenging task. Studies have been carried out mainly on platinum surfaces, both polycrystalline and single crystals, by means of different electrochemical approaches sometimes coupled to other in situ and on line techniques. [4][5][6][7][8][9][10][11][12][13][14][15][16] In most of these reports, the focus stands on the electrocatalytic aspects of the methanol oxidation and encompasses questions such as the relationship between reaction rate and applied potential, the impact of the interfacial structure on reaction rate and selectivity, and the nature and geometry of adsorbates, to list a few. By far less studied however are the issues related to the complex kinetic aspects associated to the electrooxidation of methanol.In o...

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Section: In Situ Ftir Experimentsmentioning

confidence: 99%

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Martins¹,

Batista²,

Sitta³

et al. 2008

J. Braz. Chem. Soc.

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“…Oscillatory phenomena and other nonlinear phenomena such as bistability and spatiotemporal patterns are frequently observed in metal and alloy electrodissolutionpassivation processes (Hudson & Tsotsis, 1994;Koper, 1996a;Krischer, 1999;Krischer, 2003b). Current oscillations during the Fe electrodissolution-passivation in acid solutions were reported as early as 1828 (Fechner, 1828).…”

Section: Introductionmentioning

confidence: 99%

Oscillatory Phenomena as a Probe to Study Pitting Corrosion of Iron in Halide-Containing Sulfuric Acid Solutions

Sazou¹,

Pavlidou²,

Diamantopoulou³

et al. 2012

Pitting Corrosion

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“…[8][9][10] Electrochemistry is an ideal playground for the study of dynamic instabilities because here most experiments are carried out under conditions far from thermodynamic equilibrium. It is therefore not surprising that the majority of known bistable, oscillating, and chaotic reactions is found in electrochemistry.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Waves on Patterned Surfaces: Propagation through Narrow Gaps and Channels

2001

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The dissolution and corrosion of iron and certain types of steel can involve the propagation of electrochemical waves. Low-carbon steel plates covered by nitric acid solutions self-organize pseudo-two-dimensional wave patterns which share many features with reaction-diffusion waves in excitable systems. Here, we investigate the dynamics of these electrodissolution waves in the presence of geometrical constraints. A simple procedure for the preparation of insulating, millimeter-scale obstacles is presented, which allows the controlled, local protection of the metal surface. This method is used in the measurement of the material consumption rate per wave [(850 ( 50) nm/wave or 6-7 g/(m 2 wave)] as well as for the study of front propagation through narrow gaps and long channels. In channels, the wave velocity decreases with decreasing width from 10 to 4 mm/s. Propagation failures occur within the channel if its width is smaller than 0.2-0.4 mm. These results indicate that the obstacles have sink-like boundaries. For the estimation of the critical nucleation size in this system, we prepared short and narrow gaps that induce wave blockage for openings smaller than 0.65 ( 0.1 mm.

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Principles of Temporal and Spatial Pattern Formation in Electrochemical Systems

Cited by 72 publications

References 150 publications

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Oscillatory Phenomena as a Probe to Study Pitting Corrosion of Iron in Halide-Containing Sulfuric Acid Solutions

Electrochemical Waves on Patterned Surfaces: Propagation through Narrow Gaps and Channels

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