Instabilities and oscillations in simple models of electrocatalytic surface reactions

Koper, Marc T. M.; Sluyters, J.H.

doi:10.1016/0022-0728(93)03248-n

Cited by 130 publications

(101 citation statements)

References 35 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: Resultsmentioning

confidence: 99%

“…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. 42 This ohmic drop can be induced either by decreasing the electrolyte conductivity or by inserting an external resistance between the working electrode and the potentiostat. Changing the solution conductivity would bring some difficulties, namely: (i) changes in the chemistry of the system; (ii) limited range of resistances achievable; and (iii) the experimental inconvenient of changing the electrolyte solution for each experiment.…”

Section: Resultsmentioning

confidence: 99%

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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: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

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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“…The Koper-Sluyters electrocatalytic reaction (KS-reaction) is a chemical reaction corresponding to the following kinetic scheme (written by the symbols used by the authors [2]): of X; δ is the thickness of the Nernst diffusion layer; k a , k e , k d are the rate constants for adsorption, desorption and electron transfer, respectively. The oxidation products P are assumed not to be adsorbed and to leave neighborhood of the interface.…”

Section: Mathematical Model Of the Koper-sluyters Electrocatalytic Rementioning

confidence: 99%

“…The oxidation products P are assumed not to be adsorbed and to leave neighborhood of the interface. The mathematical model of the KS-reaction in dimensionless form is [2] …”

Section: Mathematical Model Of the Koper-sluyters Electrocatalytic Rementioning

confidence: 99%

“…On the other hand, there is a number of modern technologies, such as chemical industry and the energy sector, requiring the creation of the reactors substantially non-equilibrium regimes, including oscillatory and, on the contrary, there is the need to generate and control the self-oscillatory regimes. In this paper we investigate several types of oscillations in the one model of electrochemical reactor [2]: the oscillations of relaxation type, small oscillations (when the stable limit cycle is small), and the critical oscillations (the canards [3,4]). …”

Section: Introductionmentioning

confidence: 99%

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Study of Oscillatory Processes in the One Model of Electrochemical Reactor

Firstova

Shchepakina

2016

Collection of Selected Papers of the II International Conference on Information Technology and Nanotechnology

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Fronten, Wellen und stationäre Muster in elektrochemischen Systemen

2001

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Oszillatorisches Verhalten ist bei nahezu allen elektrochemischen Reaktionen in einem bestimmten, wenn auch in manchen Fällen kleinen Bereich der externen Parameter beobachtet worden. Es ist jedoch erst während der letzten zehn Jahre gelungen, eine einheitliche Erklärung für das Auftreten dieser zeitlichen Selbstorganisationsphänomene bei den chemisch völlig unterschiedlichen elektrochemischen Reaktionen zu geben. Dieser Durchbruch gelang durch die Anwendung von Methoden und Konzepten, die in der nichtlinearen Dynamik entwickelt wurden, um die spontane Bildung von Ordnung in unterschiedlichen Disziplinen zu beschreiben. Dies ist wiederum nur möglich, weil auf einem gewissen Abstraktionsniveau diese Gesetzmäßigkeiten universell sind. Oszillationen sind nur eine mögliche Manifestation nichtlinearen Verhaltens. Beispiele anderer Erscheinungsformen, die häufig mit zeitlichen Instabilitäten eng verbunden sind, sind räumliche Strukturen und Wellen. Ausgelöst durch den theoretischen Fortschritt sowie die Entwicklung neuer experimenteller Methoden wurden während der letzten Jahre gezielte Untersuchungen zur räumlichen Musterbildung in elektrochemischen Systemen durchgeführt, die inzwischen in vielen Fällen eine Vorhersage erlauben, unter welchen Bedingungen eine räumliche oder zeitliche Strukturbildung zu erwarten ist. Dies eröffnet Perspektiven, nichtlineare Effekte zu nutzen, etwa zur Ausbeutesteigerung bei elektrokatalytischen Reaktionen. In diesem Aufsatz werden die physikalisch‐chemischen Mechanismen diskutiert, die zur Musterbildung in elektrochemischen Systemen führen, gleichzeitig werden die übergeordneten allgemeinen Prinzipien betont, die auch für Selbststrukturierungsprozesse in vielen chemischen und biologischen Systemen verantwortlich sind.

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Instabilities and oscillations in simple models of electrocatalytic surface reactions

Cited by 130 publications

References 35 publications

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Study of Oscillatory Processes in the One Model of Electrochemical Reactor

Fronten, Wellen und stationäre Muster in elektrochemischen Systemen

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