Hydrogen adsorbed on platinum

Inelastic neutron TOF spectra have also been obtained for hydrogen adsorbed on platinum powders (31,32). Both experiments observed a sharp surface vibratory mode of the hydrogen near 400... 

Figure 9. Corrected inelastic neutron spectrum for hydrogen adsorbed on platinum...

A.M. Baro, H. Ibach, H.D. Brachmann (1979). Surf Sci., 88, 384-398. Vibrational modes of hydrogen adsorbed on platinum (111) adsorption site and excitation mechanism. 

H. Asada, T. Toya, H. Motohashi, M. Sakamoto Y. Hamaguchi (1975). J. Chem. Phys., 63, 4078 - 4079. Study of hydrogen adsorbed on platinum by neutron inelastic scattering spectroscopy. 

Preparation of Alloy Type Sn-Pt/Si02 Catalysts. Supported bimetallic Sn-Pt catalysts can be prepared using different methods and approaches. However, exclusive formation of alloy type nanoclusters can be achieved by using methods of surface organometallic chemistry, namely by applying Controlled Surface Reactions (CSRs) between hydrogen adsorbed on platinum and tin tetraalkyls. 

As the experiment gives a value within 1% of Qh, it is concluded that the model is correct and that hydrogen adsorbs on platinum at one atom per site. 

Szabo S, Nagy F. 1978. Investigations of bismuth adsorption via the ionization of hydrogen adsorbed on platinized platinum in hydrochloric acid solutions. J Electroanal Chem 87 261-265. 

EELS has been used to study the kinetics of relatively slow surface reactions, such as the hydrogen-deuterium exchange in benzene adsorbed on platinum [54], In... 

Bismuth promotion suppresses the hydrogen sorption on platinum (curves b-d). The peak at -0.05 V indicates the oxidation of adsorbed bismuth, which overlaps the OH adsorption on uncovered platinum surface sites 18). Bismuth adatoms are discharged in the low potential region (Bi°) and occupy three platinum sites at low surface coverages. The structure of the oxygen-containing species are (BiOH), (BiO), and [Bi(OH)J,d 19). 

Adsorption of CD on palladium showed distinct differences from that on platinum, which is already apparent from the spectra compared in Fig. 33. The ATR spectra did not show any indication of the presence of a species covalently bound by Pt C ci-bond (a-hydrogen abstraction, species 2 in the case of platinum). The strongly adsorbed 7i-bonded flat species (1 and T) were found to be more favored on platinum, whereas on palladium the tilted, nitrogen lone-pair-bound species (3 ) were dominant. Furthermore, the comparative study showed that CD is more strongly adsorbed on platinum than on palladium, indicated by the more prominent shift of the vibrational modes with respect to the free molecule on platinum than on palladium. 

Thus, at 372°C. and over the range of pressures and hydrogen to n-pentane ratios covered in the investigation, it appears that the proposed mechanism can account in large part for the observed kinetic data. However, Starnes and Zabor (S8) have proposed an alternative mechanism, based on their studies of n-pentane isomerization over platinum-alumina-halogen catalysts. They postulate that the paraffin is adsorbed on platinum sites with dissociation of a hydrogen atom, followed by polarization of the adsorbed species. 

Free Energy of Adsorption of Hydrogen Adsorbed on Partially Sulfurized Platinum... 

Consider the following example, showing the high sensitivity that can be achieved by measurement of the current. The charge required to form a monolayer of adsorbed hydrogen atoms on platinum in the reaction... 

P. I. Dolin and B. V. Ershler, "Kinetics of Processes on the Platinum Electrode I. The Kinetics of the Ionization of Hydrogen Adsorbed on a Platinum Electrode," Acta Physicochimica URSS, 13 (1940) 747-778. 

The fact that products are not detected may be due to an IP effect as described above. For n > 4 hydrogen uptake increases progressively as the number of constituent atoms increases, and it is estimated that saturation has occurred for clusters containing more than ten atoms. Hydrogen chemisorption on platinum surfaces is generally weak, and even the most strongly bound adsorbed state on a stepped surface is fully desorbed by 450 The expected... 

In this work, we investigated the preparation of bimetallic Pt-Re catalysts by surface redox reaction between hydrogen adsorbed on a parent monometallic platinum/alumina catalyst and the cation of the second metal (Re) according to the following reaction ... 

Apart from poisoning by adsorbing impurities, the working electrode potential can also contribute to suppress electrocatalytic activity. Platinum metals, for instance, passivate or form surface oxygen and oxide layers above 1 V (Section IV,D), which inhibit Oj reduction (779,257,252) and oxidation of carbonaceous reactants (7, 78, 253, 254) however, decomposition of hydrogen peroxide on platinum is accelerated by oxygen layers (255). Some electrocatalysts may corrode or dissolve, especially in acidic electrolytes, while reactants may contribute to dissolution. Thus, ethylene oxidation on palladium to acetaldehyde proceeds via a Pd-ethylene complex, which releases colloidal palladium in solution (28, 29). Equivalent to this is the surface roughening and the loss of Pt in gas phase ammonia oxidation (256, 257). 

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