Progress in the Study of Methanol Oxidation by<i>In Situ, Ex Situ</i>and On‐Line Methods

Iwasita‐Vielstich, T.

doi:10.1002/9783527616756.ch3

Cited by 57 publications

(14 citation statements)

References 85 publications

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“…Representative oxidation current traces recorded on the different samples during continuous potentiodynamic methanol oxidation are plotted in Figure . They largely reproduce the well-known bell-shaped CV traces known for the MOR on polycrystalline Pt electrodes ,,,, or on carbon-supported Pt/C catalysts. ,,, In the plots, the currents are magnified by a factor of 2 for the HCL-17 and by a factor of 10 for the HCL-04 sample.…”

Section: Resultssupporting

confidence: 59%

“…In the present study, we used these model catalysts for a systematic investigation of transport effects in the electrocatalytic oxidation of methanol (methanol oxidation reaction, or MOR). Both from fundamental aspects and due to its potential application in direct methanol fuel cells (DMFCs), this reaction has been studied extensively; excellent reviews are given, e.g., in refs − . A better understanding of the methanol oxidation mechanism, including the transport effects investigated in this study, is therefore of considerable value not only for fundamental reasons, but also for further improvements in DMFC technology.…”

Section: Introductionmentioning

confidence: 98%

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Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

et al. 2009

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Transport effects in the methanol oxidation reaction (MOR) were investigated using nanostructured Pt/glassy carbon (GC) electrodes and, for comparison, a polycrystalline Pt electrode. The nanostructured Pt/GC electrodes, consisting of a regular array of catalytically active cylindrical Pt nanostructures with 55 +/- 10 nm in diameter and different densities supported on a planar GC substrate, were fabricated employing hole-mask colloidal lithography (HCL). The MOR measurements were performed under controlled transport conditions in a thin-layer flow cell interfaced to a differential electrochemical mass spectrometry (DEMS) setup. The measurements reveal a distinct variation in the MOR activity and selectivity (product distribution) with Pt nanostructure density and with electrolyte flow rate, showing an increasing overall activity, reflected by a higher Faradaic reaction current, as well as a pronounced increase of the turnover frequency for CO(2) formation and of the CO(2) current efficiency with decreasing flow rate and increasing Pt coverage. These findings are discussed in terms of the "desorption-readsorption-reaction" model introduced recently (Seidel et al. Faraday Discuss. 2008, 140, 67). Finally, consequences for applications in direct methanol fuel cells are outlined.

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Section: Resultssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 98%

Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

et al. 2009

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“…This research was stimulated by the development of proton exchange membrane fuel cells (PEMFCs) and direct alcohol fuel cells (DAFCs). As regards the anode performance, its electrocatalytic activity can be decreased by CO chem , which is an intermediate of alcohol oxidation in DAFC − or is found in H 2 (g) produced by hydrocarbon reforming. , In both cases, CO chem is considered a surface poison because it strongly chemisorbs on Pt-containing nanoparticles, reducing the number of surface sites at which the fuel (H 2 or alcohol) oxidation can take place, and gives rise to a high overpotential for the CO chem oxidative stripping. , On the other hand, the strong affinity of CO to Pt makes it a suitable molecule for probing surface structure–reactivity relations , and for examining the electrocatalytic activity of Pt nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Evidence of an Eley–Rideal Mechanism in the Stripping of a Saturation Layer of Chemisorbed CO on Platinum Nanoparticles

et al. 2012

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The oxidative stripping of a saturation layer of CO(chem) was studied on platinum nanoparticles of high shape selectivity and narrow size distribution. Nanospheres, nanocubes, and nano-octahedrons were synthesized using the water-in-oil microemulsion or polyacrylate methods. The three shapes allowed examination of the CO(chem) stripping in relation to the geometry of the nanoparticles and presence of specific nanoscopic surface domains. Electrochemical quartz crystal nanobalance (EQCN) measurements provided evidence for the existence of more than one mechanism in the CO(chem) stripping. This was corroborated by chronoamperometry transient for a CO(chem) saturation layer at stripping potentials of E(strip) = 0.40, 0.50, 0.60, and 0.70 V. The first mechanism is operational in the case of CO(chem) stripping at lower E(strip) values; it proceeds without adsorption of anions or H(2)O molecules and corresponds to desorption of a fraction of CO(chem) in the form of a prepeak in voltammograms or in the form of an exponential decay in chrono-amperometry (CA) transients. The second mechanism is operational in the desorption of the remaining CO(chem) at higher E(strip) values and gives rise to at least two voltammetric peaks or two CA peaks. Analysis of the experimental data and modeling of the CA transients lead to the conclusion that the stripping of a saturation layer of CO(chem) first follows an Eley-Rideal mechanism in the early stage of the process and then a Langmuir-Hinshelwood mechanism.

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“…A fuel cell (FC) is a device where the energy of fuels such as hydrogen, alcohols or hydrocarbons is converted into electricity. 1,2 The principle of a FC function is illustrated in Figure 1, for a CH 3 OH/O 2 fuel cell. The fuel, CH 3 OH and H 2 O are continuously fed in the anode compartment.…”

Section: Introductionmentioning

confidence: 99%

Fuel cells: spectroscopic studies in the electrocatalysis of alcohol oxidation

Iwasita¹

2002

J. Braz. Chem. Soc.

101

136

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Métodos spectroscópicos modernos são úteis na elucidação de mecanismos eletroquímicos complexos, como os que ocorrem durante a oxidação de pequenas moléculas orgânicas (CH 3 OH, HCOH, HCOOH). Neste trabalho apresentamos o uso de métodos espectroscópicos para o estudo da oxidação de álcoois em eletrodos de platina ou binários principalmente constituídospor Pt. Estas reações são importantes para o desenvolvimento de sistemas anódicos em células a combustível. Espectrometria de massa e Espectroscopia de infra-vermelho FT permitem estabelecer os intermediários e produtos de reação, bem como a dependência da quantidade das espécies no potencial aplicado. FTIR e microscopia de tunelamento por varredura contribuem para o entendimento dos efeitos da estrutura de superfície na velocidade de reação. Exemplos da oxidação do etanol e metanol são apresentados em catalisadores de platina puros e modificados.Modern spectroscopic methods are useful for elucidating complex electrochemical mechanisms as those occurring during the oxidation of small organic molecules (CH 3 OH, HCOH, HCOOH). In the present paper it is shown the use of spectroscopic methods to study the oxidation of alcohols on platinum or Pt-based binary electrodes. These reactions are of importance in conexion with the development of anode systems for use in fuel cells. Mass spectrometry and FT infrared spectroscopy allow to establishing the reaction intermediates and products and the dependence of the amount of species on the applied potential. FTIR and scanning tunneling microscopy contribute to understand the effects of the surface structure on the rate of reaction. Examples are presented for methanol and ethanol oxidation at pure and modified Pt catalysts.

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Progress in the Study of Methanol Oxidation byIn Situ, Ex Situand On‐Line Methods

Cited by 57 publications

References 85 publications

Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

Evidence of an Eley–Rideal Mechanism in the Stripping of a Saturation Layer of Chemisorbed CO on Platinum Nanoparticles

Fuel cells: spectroscopic studies in the electrocatalysis of alcohol oxidation

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