Mechanism of the Dissociation and Electrooxidation of Ethanol and Acetaldehyde on Platinum As Studied by SERS

Lai, Stanley C. S.; Kleyn, S.E.F; Roşca, Victor; Koper, Marc T. M.

doi:10.1021/jp807350h

Cited by 177 publications

(173 citation statements)

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“…In the oxidation mechanism, three different products can be obtained: acetaldehyde, acetic acid and CO2, exchanging 2, 4 and 12 electrons respectively. Acetic acid is a stable product since its oxidation takes place at very high potentials [5] , thus the challenge is to break the C-C bond either in ethanol [6,7] or acetaldehyde [8] to obtain CO2.Among pure metals, platinum has the highest catalytic activity in acid media, but the final product in the oxidation is mixture of CO2 and acetic acid, whose ratio strongly depends on the surface structure. [9] In order to increase the activity of platinum, other metals, namely, Ru, [8,10] Os, [11,12] Sn [7] and Rh [13] have been added to the surface to diminish the overpotentials and to increase the selectivity of the oxidation towards the formation of CO2.…”

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confidence: 99%

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confidence: 99%

“…[9] In order to increase the activity of platinum, other metals, namely, Ru, [8,10] Os, [11,12] Sn [7] and Rh [13] have been added to the surface to diminish the overpotentials and to increase the selectivity of the oxidation towards the formation of CO2. The effect of these metals in the oxidation mechanism has been explained on the basis of the bifunctional mechanism [14] and ligand effect.…”

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Unusually High Activity of Pt Islands on Rh(1 1 1) Electrodes for Ethanol Oxidation

et al. 2013

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The electrooxidation of ethanol has been widely studied since its possible application in PEM cells. Many efforts have been devoted to disentangle its oxidation mechanism and how this mechanism depends on the ethanol concentration and the surface structure and composition of the electrode. [1][2][3][4] The goal is to obtain CO2 as final product at the lowest potential and the highest current. In the oxidation mechanism, three different products can be obtained: acetaldehyde, acetic acid and CO2, exchanging 2, 4 and 12 electrons respectively. Acetic acid is a stable product since its oxidation takes place at very high potentials [5] , thus the challenge is to break the C-C bond either in ethanol [6,7] or acetaldehyde [8] to obtain CO2.Among pure metals, platinum has the highest catalytic activity in acid media, but the final product in the oxidation is mixture of CO2 and acetic acid, whose ratio strongly depends on the surface structure. [9] In order to increase the activity of platinum, other metals, namely, Ru, [8,10] Os, [11,12] Sn [7] and Rh [13] have been added to the surface to diminish the overpotentials and to increase the selectivity of the oxidation towards the formation of CO2. The effect of these metals in the oxidation mechanism has been explained on the basis of the bifunctional mechanism [14] and ligand effect. [15] From previous results, it seems clear that the only surface modifier that increases the CO2/acetaldehyde ratio is Rh, [13] although the overall reaction rate is lower. On the other hand, the opposite combination, Pt deposited on Rh electrodes has not been studied yet. Rh electrodes are not active for the oxidation of ethanol. However, it has been shown that a single layer (or submonolayer) of a metal deposited on a different substrate can have electrocatalytic activities larger than any of the two bulk metals. [16,17] In general, the metal overlayer has interatomic distances that are different from the bulk metal, since it accommodates its structure to that of the underneath substrate. This effect causes a change in the electronic properties of the overalyer and can increase (or decrease) the catalytic properties.[18] The aim of this work is to determine the electrochemical behaviour of Rh electrodes modified by Pt (sub)monolayers for ethanol oxidation, analysing the effect of the surface composition on the mechanism using in situ FTIR spectroscopy. [19] For the clean Rh(111) electrode, the voltammogram in sulphuric acid solution shows a pair of quasi-reversible peaks at 0.15 and 0.06 V, which are associated to the competitive adsorption of hydrogen/sulphate on the electrode surface. [20,21] In the initial deposition stages of Pt, these peaks become significantly sharper and more reversible. Although the explanation on the origin of such change is beyond the scope of this manuscript, it should be recalled that the interaction of water with adsorbates is different on platinum and rhodium. For instance water and CO adsorbed on Pt(111) show repulsive interactions whereas attractive interac...

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Unusually High Activity of Pt Islands on Rh(1 1 1) Electrodes for Ethanol Oxidation

et al. 2013

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“…It has been reported earlier [39], that acetaldehyde is a possible intermediate on the C-C bond breaking from ethanol at potentials as low as 0.1 V.…”

Section: Ftir Experimentsmentioning

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Trimetallic catalyst based on PtRu modified by irreversible adsorption of Sb for direct ethanol fuel cells

Figueiredo

Sorsa

Arán‐Ais

et al. 2015

Journal of Catalysis

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Abstract:In this work, PtRu/C-Sb materials prepared by adding a Sb salt to the ink of commercial PtRu/C were studied as catalysts for ethanol oxidation. The prepared trimetallic catalysts showed enhanced properties for ethanol oxidation trough a wide range of surface coverages. However, coverage higher than 0.7 of Sb on PtRu/C causes the decrease of the catalytic activity suggesting that specific sites composed by the 3 metals are necessary to achieve the highest performance. In situ Fourier Transformed Infrared Spectroscopy experiments were also performed to compare the reaction products of the bimetallic and trimetallic catalysts. The catalysts were also tested under fuel cell conditions. Also in this case, higher power densities, higher open circuit voltages and better stability than the bimetallic substrate were found. With this catalyst preparation method, the catalysts showed 2 times higher current densities than for the PtRu catalysts and 6 times better than for pure Pt anodes.

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“…In recent years, a number of in situ spectroscopic techniques have been applied to the issue of composition. This includes the identification in the adlayer of adsorbed carbon monoxide (CO) (2-9), adsorbed acetaldehyde and acetyl (8)(9)(10)(11)(12)(13)(14)(15)(16), adsorbed acetate (17)(18)(19)(20), and adsorbed methyl group (CH x ) (21)(22). There is evidence for the existence of all of those species, besides acetate, at potentials below ~0.5 V and for adsorbed acetate at higher potentials.…”

Section: Introductionmentioning

confidence: 99%

Coulometric Study of Ethanol Adsorption at a Polycrystalline Platinum Electrode

Gilman¹

2011

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Mechanism of the Dissociation and Electrooxidation of Ethanol and Acetaldehyde on Platinum As Studied by SERS

Cited by 177 publications

References 59 publications

Unusually High Activity of Pt Islands on Rh(1 1 1) Electrodes for Ethanol Oxidation

Unusually High Activity of Pt Islands on Rh(1 1 1) Electrodes for Ethanol Oxidation

Trimetallic catalyst based on PtRu modified by irreversible adsorption of Sb for direct ethanol fuel cells

Coulometric Study of Ethanol Adsorption at a Polycrystalline Platinum Electrode

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