Silver oxide, chemisorption

The surface of the silver reaction channels was enhanced by means of the oxidation and outgassing reduction (OAOR) process, which relies on oxidation at 250 °C using pure oxygen and subsequent reduction. An increase in surface area by a factor of 2-3 was reached as indicated by chemisorption data. 

Chemisorption of oxygen at Ag(110) at 300 K forms added rows of-Ag-O-extending along the [001] direction much like those observed with Cu(110). At saturation the monolayer, as with Cu(110), has a (2 x 1)0 structure.16 On exposure to ammonia at 300 K, Guo and Madix established17 that this oxide structure undergoes extensive restructuring where the added silver atoms in the monolayer are released to form nanoscale islands with the formation of... 

Buckley, A. N., 1994. A survey of the application of X-ray photoelectron spectroscopy to flotation research. Colloids Surf, 93 159 - 172 Buckley, A. N. and Woods, R., 1995. Identifying chemisorption in the interaction of thiol collectors with sulphide minerals by XPS adsorption of xanthate on silver and silver sulphide. Colloids and Surfaces A Physicochemical and Engineering Aspects, 104,2 - 3 Buckley, A. N. and Woods, R., 1996. Relaxation of the lead-deficient sulphide surface layer on oxidized galena. Journal of Applied Electrochemistry, 26(9) 899 - 907 Buckley, A. N. and Woods, R., 1997. Chemisorption—the thermodynamically favored process in the interaction of thiol collectors with sulphide minerals. Inert. J. Miner. Process, 51 15-26... 

The excess negative charge located in the interior of metallic silver colloids could also be transferred to other electron acceptors, including methylviologen, nitrobenzene, nitropyridinium oxide, anthracene quinone sulfonic add, and potassium cyanohexaferrate(III)[506, 531], The efficiency and, indeed, the direction of electron transfer were found to depend on the position of the Fermi level of the surface-modified silver particles. For example, chemisorption of AgN to a silver particle is shown to result in a shift of the Fermi level to a more positive potential, as shown in the lower line in Fig. 84. 

Fig. 84 (Upper) Schematic presentation of surface complexation (preoxidation) by a nucleophilic reagent N and final oxidation of the silver particle by oxygen. (Lower) Chemisorption of a complex AgN and final reduction of the silver ions in chemisorbed AgN by excess electrons deposited by reducing radicals. In both parts of the figure, the changes in the position of the Fermi level in the colloidal silver particles are indicated [531]...

Optimum oxidation conditions involve a maximum of silver carbonate surface available for chemisorption. That is why, increasing the amount of Celite on which silver carbonate is precipitated produces a higher rate of oxidation. Although, above a value of 900 g of Celite per mol of silver carbonate, a slight decrease of oxidation speed is observed resulting from a dilution effect.40... 

The formation of some organic hydroperoxides by oxidation with molecular oxygen is catalytically promoted by metals like silver or copper 171). A dissociative chemisorption of oxygen cannot be active in these processes they probably proceed via the chemisorption of O7 ions (or O2 molecules forming a covalent bond resonating with an ionic bond). 

Key Words Ethylene oxide, Ethylene, Epoxidation, Silver, Cl promotion, Cs promotion. Promotion, Selectivity, Oxametallacycle, Adsorption, Desorption, Chemisorption, Activation energy, Ag-O bond. Reaction mechanism, Oxidation, Cyclisation, Heterogeneous catalysis, Selective oxidation, Eletrophilic oxygen. Nucleophilic oxygen. Subsurface O atoms, Ag/a-A Oj catalyst. 2008 Elsevier B.V. 

The conductor catalysts are the metals (silver, platinum, vanadium, iron, etc.) and have the property of chemisorption by electron transfer. The semiconductor catalysts are the oxides, such as NiO, CU2O, and ZnO. These materials have the capability of interchanging electrons from the filled valence bands in a compound when sufficient energy is provided,... 

Reactions were also monitored by SERS. Yamada et discussed the reaction of rose bengal adsorbed on a ZnO electrode. This is an example of the use of the resonance enhancement to gain enough sensitivity. Billmann et followed the chemisorption of cyanide on silver, and detected the formation of the various cyanides on the surface. Similarly, Loo investigated halide complexes on a gold electrode. Pemberton and Buck " used SERS to see the adsorption of diphenylthiocarbazone and its oxidation into... 

A system of controlled size, supported silver particles, such as Ag-PFSA, could be convenient for the study of chemisorption reactions, particularly those of C>2, because of their importance in catalytic oxidations. Experiments involving the formation of silver particles upon reduction of Ag -PFSA and their subsequent exposure to oxygen, will be discussed here.(20)... 

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