A comparison of gas-phase and electrochemical hydrogenation of ethylene at platinum surfaces

Wiȩckowski, Andrzej; Rosasco, Stephen D.; Salaita, Ghaleb N.; Hubbard, Arthur T.; Bent, Brian E.; Zaera, Francisco; Somorjai, Gábor A.

doi:10.1021/ja00307a015

Cited by 102 publications

(75 citation statements)

References 8 publications

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“…Nearly 100% of this car_bon is partially hydrogenated and, as shown in Figure 24 for a Rh(111) surface, exists on the surface as ethylidyne species. Analogous results for a Pt(111) catalyst have been published [61]. It was found that these monolayers of ethylidyne were quite stable under one atmosphere of hydrogen or deuterium [6,63].…”

Section: Ethylene Hydrogenationsupporting

confidence: 72%

Bonding and chemistry of hydrocarbon monolayers on metal surfaces

Bent

Somorjai

1989

Advances in Colloid and Interface Science

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Section: Ethylene Hydrogenationsupporting

confidence: 72%

Bonding and chemistry of hydrocarbon monolayers on metal surfaces

Bent

Somorjai

1989

Advances in Colloid and Interface Science

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“…Both free energies and heats of reaction must be considered for analysis (5-7). Since AG = AH -TAS (18) the maximum amount of electrical energy recoverable is diminished by TAS. Some idea of the highest possible recovery of heat as electricity can be obtained from comparing G°R and AH°R values in Table 1.…”

Section: Procedures and Conditionsmentioning

confidence: 99%

“…It can be noted that conventional catalytic hydrogenation can be conjectured to take place by a process analogous to electrogenerative hydrogenation. However, recent results (18) indicate that this is probably not a completely valid analogy since heterogeneous catalysis takes place on a carbonaceous residue while electrogenerative hydrogenation occurs at the metal surface. The analogy appears to be more valid for electrogenerative nitric oxide reduction (7,8), an inorganic process.…”

Section: Electrogenerative Catalytic Vs Conventional Catalytic Procementioning

confidence: 99%

“…Related mechanisms also have been postulated by Hubbard, etal. (18). Indeed, the hydrogenation of ethylene and unsaturated hydrocarbons at positive electrogenerative potentials has been the subject of a number of studies (10,17,18) because this is one of the few reactions that takes place heterogeneously and electrochemically.…”

mentioning

confidence: 99%

“…(18). Indeed, the hydrogenation of ethylene and unsaturated hydrocarbons at positive electrogenerative potentials has been the subject of a number of studies (10,17,18) because this is one of the few reactions that takes place heterogeneously and electrochemically. However, despite its value for model studies (16,17,19,20), hydrogenation of unsaturated hydrocarbons has been of limited interest for long term development.…”

mentioning

confidence: 99%

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Electrogenerative and related processes

Langer¹,

Card²,

Foral³

1986

Pure and Applied Chemistry

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A number of organic electrogenerative processes are described and explained by reviewing various aspects of studies associated with them. Electrogenerative hydrogenation, dehydrogenation, halogenation, and oxidation of alcohols are discussed together with possibilities for process improvement. Hydrogenation is used as a model for reviewing studies which correspond to the conventional ones of organic chemistry. The oxidation of ethanol vapor to acetaldehyde is used as an illustration of a potentially viable electrogenerative process. Generated electricity is a byproduct in electrogenerative processing and a useful indicator of the rate of reactant consumption. However, product selectivity may be lost where generation of high currents becomes the major consideration.

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Surface Analysis for Electrochemistry: Ultrahigh Vacuum Techniques

Soriaga

2000

Encyclopedia of Analytical Chemistry

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The study of processes that transpire at heterogeneous interfaces is an exceedingly difficult proposition. No single experimental technique can ever hope to unravel all the nuances of heterogeneous reactions; hence, in surface science, the use of multiple complementary methods is not uncommon. Ultrahigh vacuum electrochemistry (UHV/EC) is a term ascribed to the approach that rests upon the integration of classical electrochemical methods with surface‐sensitive analytical techniques; this strategy parallels that successfully implemented in the study of gas–solid heterogeneous catalysis. The unique surface sensitivity of the techniques adopted emanates from the use of particles (e.g. ions or electrons) that serve to interrogate the outermost layer(s) of the electrode. This surface sensitivity is tempered by the requirement that the analysis be performed in an environment (outside the electrochemical cell) that does not impede the mean‐free paths of the probe particles. Since its inception in the early 1970s, more than a thousand UHV/EC‐based studies have been published; most of the work involved polycrystalline materials and focused on the elemental composition at the electrode surface. While its importance in the study of polycrystalline surfaces cannot be trivialized, the greater value of UHV/EC appears to be in its ability to help resolve fundamental issues that intertwine interfacial structure and composition with electrochemical reactivity. It is in this context that the present review is written. A complete mechanism of an electrochemical reaction must incorporate all the physical and chemical interactions that arise between an electrified surface and its environment. The extent of such interactions depends upon several factors such as solvent, supporting electrolyte, electrode potential, reactant concentration, electrode material and surface crystallographic orientation. The traditional approach is based upon a thermodynamic treatment of the interface and its response to external perturbations. Interpretation of the results relies on phenomenological models of the interface. Although a thermodynamic treatment cannot be ignored, the need for an atomic‐level view has long been realized. One approach1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 towards the establishment of an atomic‐level description parallels that successfully implemented in the study of gas–solid heterogeneous catalysis; it rests upon the integration of classical electrochemical methods with surface‐sensitive analytical techniques. The analytical methods that exhibit surface sensitivity are based upon the mass‐selection and/or energy‐discrimination of electrons, ions, atoms or molecules scattered from solid surfaces. These particles have shallow escape depths; hence the information they bear is characteristic of the near‐surface layers. Their short mean‐free paths, however, necessitate a high vacuum (<10 −6 torr) environment. The application of such surface techniques to electrochemistry requires that the analysis be performed outside the electrochemical cell. The possibility of structural and compositional changes that accompany the removal of the electrode from solution is the major concern in UHV/EC studies. Although a myriad of surface analytical techniques is currently available, those actually employed in UHV/EC have been limited to low‐energy electron diffraction (LEED), Auger electron spectroscopy (AES), X‐ray photoelectron spectroscopy (XPS), high‐resolution electron energy loss spectroscopy (HREELS), reflection high‐energy electron diffraction (RHEED), work‐function changes, and thermal desorption mass spectrometry (TDMS). While most vacuum‐based analytical methods do not require single‐crystal surfaces, the use of uniform (monocrystalline) surfaces is a necessary aspect for fundamental studies. The low‐index crystallographic faces [(100), (110) and (111)] have been widely used because of their low free energies, high symmetries, and relative stabilities. In addition, it may be possible to reconstruct the overall behavior of polycrystalline electrodes from the individual properties of the low‐index planes. 1, 2, 3, 4 A handful of procedures for the preparation and preservation of well‐defined single‐crystal surfaces have been described. 5, 6, 7, 8 The verification or identification of initial, intermediate, and final interfacial structures and compositions is an essential ingredient in electrochemical surface science.

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A comparison of gas-phase and electrochemical hydrogenation of ethylene at platinum surfaces

Cited by 102 publications

References 8 publications

Bonding and chemistry of hydrocarbon monolayers on metal surfaces

Bonding and chemistry of hydrocarbon monolayers on metal surfaces

Electrogenerative and related processes

Surface Analysis for Electrochemistry: Ultrahigh Vacuum Techniques

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