Electrochemical and spectroscopic studies of ethanol oxidation on Pt stepped surfaces modified by tin adatoms

Colle, Vinícius Del; Souza-Garcia, Janaína; Tremiliosi‐Filho, Germano; Herrero, Enrique; Feliu, Juan M.

doi:10.1039/c1cp20546c

Cited by 77 publications

(89 citation statements)

References 34 publications

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“…For the surfaces vicinal to the (111) stereographic pole, that is, those containing terraces with (111) symmetry, significant effects in reactivity of the surface have been found. For those surfaces, the step sites are the active sites on these surfaces for the oxidation of adsorbed CO [14], the cleavage of the C-C bond in the ethanol oxidation reaction [15][16][17][18], or the formation of CO in the formic acid oxidation reaction [19][20][21], whereas the (111) terrace sites have a negligible activity for those processes. On the other hand, for the surfaces vicinal to the (100) pole, the reactivity of the (100) domains is much less affected by the presence of the steps.…”

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confidence: 99%

On the electrochemical properties of platinum stepped surfaces vicinal to the (100) pole. A computational study

Ferre-Vilaplana

Gisbert

Herrero

2014

Electrochimica Acta

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Please cite this article as: Adolfo Ferre-VilaplanaRuben GisbertEnrique Herrero On the electrochemical properties of platinum stepped surfaces vicinal to the (100) pole. A computational study (2014), http://dx.doi.org/10.1016/j.electacta. 2014.01.138 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract.DFT studies on platinum stepped surfaces have been carried out in order to understand the differences in the electrochemical behavior between the surfaces with (111) and (100) terraces. Thus, adsorption energies of different species on selected surfaces have been computed. For the adsorption of Bi and Cu on the Pt(553) and Pt(711) surfaces, it has been found that that the adsorption energy on the site corresponding to the step decoration for the Pt(553) surface is ca. 0.5 eV higher than that calculated on the (111) terrace sites. On the other hand, there is no preferential adsorption site for Cu or Bi on the Pt(711) surface, since the energy differences between the different sites on this stepped surface with (100) terraces are very small. CO and OH adsorption on the surface with (100) terraces, namely the Pt(100), the Pt(711) and the Pt(510) surfaces, have been also investigated. The energy differences between step sites and terrace sites for both surfaces is very small, ca. 0.2 eV for OH adsorption and <0.1 eV for CO adsorption. For OH, the preferred adsorption mode is a bridge mode, whereas the adsorption energy for the on top and bridge configurations of CO are similar on those surfaces. The comparison with previous DFT calculations indicates that the Page 2 of 29 A c c e p t e d M a n u s c r i p t 2 perturbation created by the step on the (100) terrace is significantly smaller than that created on the (111) terraces. Thus, the modification of the electrochemical properties produced by the presence of a step in the (100) terrace is minor, in agreement with the experimental results.

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Section: Page 3 Of 29mentioning

confidence: 99%

On the electrochemical properties of platinum stepped surfaces vicinal to the (100) pole. A computational study

Ferre-Vilaplana

Gisbert

Herrero

2014

Electrochimica Acta

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“…[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.…”

Section: Unusually High Activity Of Pt Islands On Rh(111) Electrodes mentioning

confidence: 99%

“…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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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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“…The strategies to improve the electrocatalysis of this reaction seek electrode materials that increase the rate of the C-C bond cleavage and catalyze step (6) at lower potentials. Some alternatives for platinum are the use of (110) stepped surfaces on (111) terraces [24] or the presence of foreign atoms adsorbed on the Pt surface [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Oxidation of ethanol on platinum nanoparticles: surface structure and aggregation effects in alkaline medium

Busó-Rogero

Solla-Gullón

Vidal‐Iglesias

et al. 2015

J Solid State Electrochem

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The ethanol oxidation reaction in 0.1 M NaOH on Pt nanoparticles with different shapes and loadings was investigated using electrochemical and spectroscopic techniques. The surface structure effect on this reaction was studied using well-characterized platinum nanoparticles. Regardless of the type of Pt nanoparticles used, results show that acetate is the main product with negligible CO2 formation. From the different samples used, the nanoparticles with a large amount (111) ordered domains have higher peak currents and a higher onset potential, in agreement with previous works with single crystal electrodes.In addition, spherical platinum nanoparticles supported on carbon with different loadings were used for studying possible diffusional problems of ethanol to the catalyst surface.The activity in these samples diminishes with the increase of Pt loading, due to diffusional problems of ethanol throughout the whole Pt nanoparticle layer, being the internal part of the catalyst layer inactive for the oxidation. To avoid this problem and prepare more dispersed nanoparticle catalyst layers, deposits were dried while the carbon support was rotated to favor the dispersion of the layer around the support. The improvement in the electrocatalytic activity for ethanol oxidation confirms the better performance of this procedure for depositing and drying.

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Electrochemical and spectroscopic studies of ethanol oxidation on Pt stepped surfaces modified by tin adatoms

Cited by 77 publications

References 34 publications

On the electrochemical properties of platinum stepped surfaces vicinal to the (100) pole. A computational study

On the electrochemical properties of platinum stepped surfaces vicinal to the (100) pole. A computational study

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

Oxidation of ethanol on platinum nanoparticles: surface structure and aggregation effects in alkaline medium

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