Study of adsorbed water on Pt during methanol oxidation by ATR-SEIRAS (surface-enhanced infrared absorption spectroscopy)

Shiroishi, Hidenobu; Ayato, Yusuke; Kunimatsu, K.; Okada, Tatsuhiro

doi:10.1016/j.jelechem.2005.04.027

Cited by 60 publications

(49 citation statements)

References 35 publications

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“…The mechanisms for both reactions are closely related, but remain in debate. Evidence supports a two-path reaction scheme for the electrooxidation of methanol on Pt, whereby it first converts to CO, which can be further oxidized to CO 2 , or directly oxidized to CO 2 , [4,5] with adsorbed bidentate formate observed during reaction and proposed as the active intermediate in this latter pathway to CO 2 [6,16,17]. Bidentate formate is also thought to be an intermediate in the oxidation and electrooxidation of formic acid on Pt [18][19][20].…”

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confidence: 84%

Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

2016

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The catalytic and electrocatalytic oxidation and reforming of methanol and formic acid have received intense interest due to potential use in direct fuel cells and as prototype models for understanding electrocatalysis. Consequently, the reaction energy diagram (energies of all the adsorbed intermediates and activation energies of all the elementary steps) have been estimated for these reactions on Pt(111) by density functional theory (DFT) in several studies. However, no experimental measurement of these energy diagrams have been reported, nor is there a consensus on the mechanisms. Here, we use energies of key intermediates on Pt(111) from single crystal adsorption calorimetry (SCAC) and temperature programmed desorption (TPD) to build a combined energy diagram for these reactions. It suggests a new pathway involving monodentate formate as a key intermediate, with bidentate formate only being a spectator species that slows the rate. This helps reconcile conflicting proposed mechanisms.

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confidence: 84%

Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

2016

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“…This fact is explained by the stabilization of the hydrogen bond in the complex and the weakened of the water/platinum interaction. Thus, adsorbed water molecules on platinum in acid media vibrates from 3500 to 3000-3100 cm −1 , but in the presence of adsorbate neighbours changes to a new vibration range due to the asymmetric stretching of the O-H bond at 3658 cm −1 [33]. Using in situ ATR-SEIRAS techniques it is demonstrated that water coexists with adsorbed carbon monoxide derived from methanol partial oxidation.…”

Section: Discussionmentioning

confidence: 99%

The Electrochemical Development of Pt(111) Stepped Surfaces and Its Influence on Methanol Electrooxidation

Téliz¹,

Díaz²,

Faccio³

et al. 2011

International Journal of Electrochemistry

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The progress in the preparation of new electrode surfaces by electrochemical treatments exhibiting high faradaic efficiencies towards industrial electrocatalytic processes has gained more attention in today's scientific community. Most of the papers report new catalysts dispersed on different substrates, but some fundamental studies required for electrochemical and physical characterizations are sometimes forgotten. In this paper, we make a full staging of two electrochemical treatments that can be conducted to enhance the electrocatalytic activity of platinum surfaces, such as, electrofacetting through square wave potential programs and constant cathodic polarizations in the net hydrogen evolution region. The cathodic treatment applied at −2 V clearly develops (111) stepped planes similarly to the electrofacetting performed after applying the square wave program between 1.40 V and 0.70 V at 2.5 kHz. The X-ray diffraction patterns of both surfaces as well as on other electrofacetted platinum electrodes are obtained for comparison purposes. Moreover, the electrocatalytic activity towards methanol electrooxidation also exhibits equivalent coulombic efficiencies and 200% higher than on polycrystalline platinum as demonstrated by linear sweep voltammetry and potentiostatic current decays.

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“…Incidentally, OH stretching band at 3660 cm ¹1 of non-hydrogen-bonded water molecules co-adsorbed with CO, observed in the absence of chloride ions, 40,41 was not observed in the presence of 1.0 © 10 ¹4 M chloride ions or higher. A similar result has been obtained by Peng et al, 27 who have observed the interfacial free water coverage decreases by a factor of ca.…”

Section: ¹1mentioning

confidence: 92%

Regeneration Oscillation Observed during Oxidation of Methanol, Formic Acid, and Formaldehyde with Chloride Ions

et al. 2014

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A new type of oscillation, which we name regeneration oscillation, is investigated in detail. The regeneration oscillation is the ordinary potential oscillation with the higher turning potential lower than 0.85 V appearing repeatedly after the potential stays at a value higher than 1.0 V for a long time, of the order of 10 min or an hour. The oscillation has been observed during the oxidation of methanol, formaldehyde, and formic acid at 315 K when their concentrations are high, 1 or 10 mol/L (M), in the presence of high chloride ion concentrations, such as 10 −2 M, at a current far lower than the maximum current for the appearance of ordinary oscillation. The reason for the appearance of regeneration oscillation has been found by voltammetry and surface-enhanced infrared absorption spectroscopy to be due to the presence of two potentials for oxidizing adsorbed CO, one shifting to a value higher than 1.0 V and the other remaining unchanged, with increasing chloride ion concentration.

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Study of adsorbed water on Pt during methanol oxidation by ATR-SEIRAS (surface-enhanced infrared absorption spectroscopy)

Cited by 60 publications

References 35 publications

Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

The Electrochemical Development of Pt(111) Stepped Surfaces and Its Influence on Methanol Electrooxidation

Regeneration Oscillation Observed during Oxidation of Methanol, Formic Acid, and Formaldehyde with Chloride Ions

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