Temperature dependence of the COads oxidation process on Pt(111), Pt(100), and Pt(110) electrodes

Herrero, Enrique; Álvarez, B.; Feliu, Juan M.; Blais, Sonia; Radovic-Hrapovic, Zorana; Jerkiewicz, Gregory

doi:10.1016/j.jelechem.2003.12.019

Cited by 79 publications

(103 citation statements)

References 52 publications

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“…4b. The voltammograms differ in a number of ways from those recorded in sulfuric acid: first, similar to CO stripping on Pt[n(111) · (111)] electrodes [35], the onset of the oxidation peaks lie at lower potentials in [30,34] perchloric than in sulfuric acid media. The faster oxidation is also observed in the number of scans needed for complete adlayer stripping, which requires only up to three cycles in perchloric media for the surfaces studied.…”

Section: Co Electrooxidation On Rhmentioning

confidence: 89%

Mechanisms of Carbon Monoxide and Methanol Oxidation at Single-crystal Electrodes

et al. 2007

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The electrochemical oxidation of carbon monoxide and methanol on single-crystal noble metal electrodes has been studied using cyclic voltammetry, chronoamperometry, in situ FTIR spectroscopy, online electrochemical mass spectrometry, and theoretical methods. The oxidation of CO was found to be enhanced by steps and defects. Furthermore, the surface diffusion rate was found to have a significant influence on the kinetics of the oxidation process: for high diffusion rates, such as the oxidation of CO on platinum, the kinetics can be described by a mean field model, while for low diffusion rates, such as CO oxidation on rhodium in sulfuric acid, a nucleationand-growth model was found to be more suitable. Voltammetric and mass spectrometric measurements on the oxidation of methanol on platinum indicate that steps enhance the overall reaction rate. In general, the selectivity towards the direct oxidation pathway through soluble intermediates was found to be higher in the absence of strongly adsorbing anions. In both perchloric and sulfuric acid, this selectivity was also found to increase with increasing step density. In sulfuric acid, Pt(111) shows the highest relative contribution for the direct pathway of all surfaces studied in that electrolyte. Based on these results, a detailed reaction scheme for the electrochemical oxidation of methanol is presented.

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Section: Co Electrooxidation On Rhmentioning

confidence: 89%

Mechanisms of Carbon Monoxide and Methanol Oxidation at Single-crystal Electrodes

et al. 2007

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“…Figure 2 shows the voltammetric profiles of the electrodes used in this work at different temperatures. For the Pt(111) electrode, as the temperature increases, sulfate adsorption shifts slightly towards more positive potentials [28,29]. All the signals related to sulfate adsorption move slightly to more positive potentials, but the effect is clearer when the position of the spike at ca.…”

Section: Temperature Effects On the Behavior Of The Electrodes In Thementioning

confidence: 99%

“…0.37 V marks the point where hydrogen adsorbed atoms are being replaced by adsorbed sulfate [33]. As can be seen, this peak shifts towards negative potential values, but is less sharp [29]. This fact indicates that the onset for the adsorption process takes place at lower potentials.…”

Section: Temperature Effects On the Behavior Of The Electrodes In Thementioning

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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“…The species involved in the initial reaction with CO ads is generally regarded to be OH ads formed by the dissociation of 95 adsorbed water 1, 6, 15-17, 29, 35, 48-50 . L-H kinetics are often written such that there is an implicit assumption that any free sites formed in the adlayer will promote the formation of OH ads through rapid spontaneous dissociative oxidative adsorption of bulk water 2,12,[51][52][53][54][55] 49,50,78,79 , it is often considered to be so transient that it is not important 5 . The third step in the oxidation of CO ads is generally ignored and assumed to be extremely fast compared to the first and second, and is implicitly assumed to be via reaction with bulk water to form H 3 O + 5, 49, 80 .…”

Section: Co Reorganisation Compared To Oh Ads Redistributionmentioning

confidence: 99%

The role of adsorbed hydroxyl species in the electrocatalytic carbon monoxide oxidation reaction on platinum

Kucernak

Offer

2008

Phys. Chem. Chem. Phys.

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The assumption that "OH ads " or other oxygen containing species is formed on polycrystalline or nanoparticulate platinum through a fast and reversible process at relatively low potentials is often made. In this paper we discuss the implications of this assumption and the difficulty in reconciling it with experimental phenomena. We show how presenting chrono-amperometric transients as log-10 log plots for potentials steps in the presence and absence of an adlayer of carbon monoxide o n polycrystalline platinum is particularly useful in understanding the time evolution of the CO oxidation reaction. When using log-log plots a clear power law decay can be observed in the transients both in the presence and absence of an adlayer of carbon monoxide. We explain this as an extension of current theory, such that the rate determining step in both cases is the formation of 15 a hydrogen bonded water-OH ads network, strongly influenced by anions, and that CO ads oxidation occurs, at least in part by the diffusion of OH ads through this network. We hypothesize that, at low potentials the formation of OH ads at active sites is fast and reversible but that transport of OH ads away from those sites may be rate limiting. The assumption that overall OH ads formation on platinum is fast and reversible is therefore highly dependent upon the platinum surface and th e 20 experimental conditions and it may not be appropriate for polycrystalline surfaces in sulphuric acid. Therefore, although the formation of OH ads on platinum in the absence of strongly adsorbing anions on 'ideal' surfaces is almost certainly fast and reversible, on realistic fuel cell relevant surfaces under non-ideal conditions this assumption cannot be made, and instead the formation of an OH ads adlayer may be somewhat slow and is associated with the formation of hydrogen bonded 25 water-OH ads networks on the surface. We expect this to be a more realistic description for what occurs during CO ads oxidation on fuel cell relevant catalysts which are highly heterogeneous and which have a highly defective surface. IntroductionThe formation of oxides on platinum surfaces at high potentials is relatively well studied yet contentious. The role of the species typically called "OH ads " in the surface catalysis of platinum catalysts is crucial in understanding a large 5 number of reactions, of which the most common example is the carbon monoxide oxidation reaction (COOR). The nature of this species is somewhat controversial, although Anderson has recently shown through theoretical ab initio charge selfconsistent methods that OH ads should form on a Pt surface at a 10 potential of about 0.6 V. Several investigators claim that OH ads is the species responsible for reacting with adsorbed CO ads , and that this is a chemical Langmuir-Hinshelwood (L-H) reaction [1][2][3][4][5][6][7] . The lowest potentials at which the COOR has been reported is 150 mV for carbon supported platinum 8 , 200 15 mV for a porous platinum electrode 9 and for polycrystalline platinum 10 , and ...

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Temperature dependence of the COads oxidation process on Pt(111), Pt(100), and Pt(110) electrodes

Cited by 79 publications

References 52 publications

Mechanisms of Carbon Monoxide and Methanol Oxidation at Single-crystal Electrodes

Mechanisms of Carbon Monoxide and Methanol Oxidation at Single-crystal Electrodes

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

The role of adsorbed hydroxyl species in the electrocatalytic carbon monoxide oxidation reaction on platinum

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