Current Oscillations during Formic Acid Oxidation on a Pt Electrode: Insight into the Mechanism by Time‐Resolved IR Spectroscopy

Samjeské, Gabor; Osawa, Masatoshi

doi:10.1002/anie.200501009

Cited by 191 publications

(177 citation statements)

References 29 publications

(14 reference statements)

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“…A remarkable smaller mean CO coverage ( CO ) of about 0.25-0.30 ML was obtained in this case. Osawa and co-workers 47,48 studied the potential oscillations in the electrooxidatioon of formic acid under similar conditions, but using Surface Enhanced Infrared Absorption Spectroscopy (SEIRAS) in a Kretschmann-type attenuated total reflection (ATR) mode, and found similar values for the mean CO . Furthermore, Osawa's set up allowed at following the changes in CO during the oscillatory electrooxidation of formic acid.…”

Section: Resultsmentioning

confidence: 98%

“…In addition, the spectroscopic determination of intermediate species known to be formed during methanol electrooxidation under regular conditions, but in oscillatory regime is a challenging task. Therefore, further studies on the Pt|H 3 COH system under oscillatory conditions using ATR-SEIRAS 47,48 would be of help to uncover the detailed mechanism responsible for the temporal instabilities discussed here.…”

Section: Resultsmentioning

confidence: 98%

“…Besides the already mentioned richer dynamic behavior, formic acid was chosen because of the considerable amount of spectroscopic data available for this system under oscillatory conditions. [46][47][48] Figure 5 shows potential oscillations obtained under galvanostatic control for the electrooxidation of formic acid on platinum and in sulfuric acid aqueous media. As observed, the potential oscillations are of relaxation-like type and about 5-6 times slower than the ones showed so far for methanol.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

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: 98%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Martins¹,

Batista²,

Sitta³

et al. 2008

J. Braz. Chem. Soc.

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“…It can be seen that between about 0.13 and -0.05 V there is a slow poisoning of the anode electrode due to carbon monox-ide adsorbed (CO ad ) from the dehydration of weakly adsorbed formic acid [10]. Another stable intermediate that also contributes to the loss of electrode activity is the bridgedbonded formate (HCOO ad ) which, like CO ad , inhibits the direct oxidation pathway of formic acid [10] [11]. Eventually the electrode reaches a critical coverage of catalytic poisons and, in order to keep the current constant, the anode overpotential increases (therefore the cell voltage decreases) leading to the formation of oxygenated species on platinum.…”

Section: Resultsmentioning

confidence: 99%

Voltage Inversion Caused by Self-organized Oscillations in a Direct Formic Acid Fuel Cell

Nogueira¹,

Varela²

2017

Matters

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“…On the other hand, the reaction route which gives directly CO 2 is called the direct oxidation route. For this route, the nature of the intermediate is still subject of discussion [4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

On the activation energy of the formic acid oxidation reaction on platinum electrodes

Perales-Rondón

Herrero

Feliu

2015

Journal of Electroanalytical Chemistry

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Abstract.A temperature dependent study on the formic acid oxidation reaction has been carried out in order to determine the activation energy of this reaction on different platinum single crystal electrodes, namely Pt(100), Pt(111), Pt(554) and Pt (544) (100) electrode, and the activation values for this process range between 20 and 100 kJ/mol. These results have been explained using a reaction mechanism in which the oxidation of formic acid requires the presence of a pre-adsorbed anion on the electrode surface.

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Current Oscillations during Formic Acid Oxidation on a Pt Electrode: Insight into the Mechanism by Time‐Resolved IR Spectroscopy

Cited by 191 publications

References 29 publications

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Voltage Inversion Caused by Self-organized Oscillations in a Direct Formic Acid Fuel Cell

On the activation energy of the formic acid oxidation reaction on platinum electrodes

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