Surface phenomena oxidation

The physical meaning of the parameter 2FNG/I is obvious It expresses the time required to form a monolayer of oxide ions on a surface with NG adsorption sites when the oxide ions are supplied at a rate I/2F. This proves that NEMCA is a surface phenomenon (not a bulk phenomenon and not a phenomenon at the tpb) taking place over the entire gas-exposed catalyst electrode surface. 

The phenomenon appears to be due to formation and destruction of some type of surface silver oxide during oxygen pumping to and from the catalyst respectively. The use of in situ surface science techniques should prove very useful for the elucidation of the exact nature of this surface oxide. 

Floatability is a- surface phenomenon and some solids are more easily floatable (such as sulfur, sulfides of the metals, graphite) than others (such as oxides, silicates, silica). 

Oxidized coal coal whose properties have been modified fundamentally as a result of chemisorptions of oxygen in the air or oxygen dissolved in ground-water. Chemisorption is a surface phenomenon rarely detectable by chemical analysis but usually detectable by petrographic examination. It reduces the affinity of coal surfaces for oil and seriously impairs coking, caking, and agglutinating properties. 

The conclusion is that spillover species permit that the correct coordination of atoms and groups of atoms at the surface of oxide catalysts be kept, thus permittting high activity and selectivity, and avoiding deactivation. The phenomenon by which a donor distinct from the real catalytic phase controls the catalytic properties of the latter is what we call a remote control. 

Although catalysis is a surface phenomenon, the spectroscopic investigation of the surface properties of tin-antimony oxides do not appear to have been pursued with an excessive degree of vigor. This may in part reflect the comparatively recent development of spectroscopic techniques with these specific powers, but it might also reflect the reluctance that some potentially... 

Surface oxidation behavior is particularly important with regard to the use of glassy metals in as-quenched state. A general observation made with binary alloys is that the more electropositive constituent of the alloy tends to segregate to the surface upon oxidation. This procedure can occur already at lower temperature, and consequently the surface of freshly prepared alloys is likely to be covered with a thin layer of oxides of this constituent. This phenomenon has certainly contributed to controversy with regard to the catalytic properties of glassy metal surfaces, since in many of the earlier investigations little care was taken of this behavior and authors tacitly assumed that the surface composition resembles the bulk composition of the quenched materials. 

In addition to the statistical nature of the interface instabilities active in diamond CVD, the orientation effect and anisotropic growth of crystals (i.e., evolutionary selection) play an important role in the observed instability phenomenon. Surface chemical reactions that occur preferentially between the growing diamond surface and oxidizing species in the combustion synthesis ambient also influence the development of the microstructure and morphology of crystals in diamond films. For example, in combustion CVD,... 

Vink has produced evidence in total conflict with previous experience which is suggested to show that the photo-oxidation of polypropylene is a bulk reaction rather than a surface phenomenon. ESCA studies, however, have shown that the photo-oxidation of polypropylene is clearly a surface phenomenon.In a recent study by Kollmann and Wood the photo-oxidation of polypropylene was found to be dependent upon the intensity of the light source. Thus, for unstabilized polymer the rate was proportional to I , whereas for stabilized polymer the rate was proportional to 1O 8-0.9 Thej-e appears to be some conflict in the literature as to whether chemical changes during the photo-oxidation of polyolefins correlate with the changes in mechanical properties.This has always been a difficult... 

Mortland (1958) briefly reviews the subject of nonbiological oxidation of ammonia in soil and concludes that the importance of this process in soil is not completely known. He states that although many experiments have failed to show appreciable nonbiological oxidation, it is possible that such reactions may occur in soils, though perhaps to a small degree, under the influence of such radiations as sunlight, cosmic rays, and natural radioactivity. Russell (1961) concludes that there seems to be Uttle doubt that ammonia can be oxidized to nitrite in solution photochemically, but the importance of photooxidation to nitrite even in tropical soils, where it can only be a surface phenomenon, is still undecided. 

Note We do not expect that the quantum size effect of gold NPs in the studied range affects the protein binding. A surface phenomenon like catalysis by gold NPs (i.e., CO oxidation) presents a quantum size effect for gold NP size of < 5 nm." ... 

SOMC is purely a surface phenomenon where an organometallic complex binds selectively with the surface by covalent (or sometimes ionic or both) bonds. One can then access to its electronic configuration and oxidation state, and this leads to a better understanding of the reaction mechanism. In SOMC, the surface acts as a ligand, which means one can tune the catalytic activity of the organometallic with the surface... 

Wang, C., Cai, Y. and Wachs, I. (1999). Reaction-induced Spreading of Metal Oxides onto Surfaces of Oxide Supports during Alcohol Oxidation Phenomenon, Nature, and Mechanisms,... 

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