Metal oxide-based compounds

Metal Oxide-Based Compounds as Electrocatalysts for Oxygen Reduction Reaction... 

Since the first synthesis of mesoporous materials MCM-41 at Mobile Coporation,1 most work carried out in this area has focused on the preparation, characterization and applications of silica-based compounds. Recently, the synthesis of metal oxide-based mesostructured materials has attracted research attention due to their catalytic, electric, magnetic and optical properties.2 5 Although metal sulfides have found widespread applications as semiconductors, electro-optical materials and catalysts, to just name a few, only a few attempts have been reported on the synthesis of metal sulfide-based mesostructured materials. Thus far, mesostructured tin sulfides have proven to be most synthetically accessible in aqueous solution at ambient temperatures.6-7 Physical property studies showed that such materials may have potential to be used as semiconducting liquid crystals in electro-optical displays and chemical sensing applications. In addition, mesostructured thiogermanates8-10 and zinc sulfide with textured mesoporosity after surfactant removal11 have been prepared under hydrothermal conditions. 

Despite their solid appearance, within the gel the liquid component is mobile and is only held by capillary forces. The solid network can be either a covalent polymer or a supramolecular assembly of small molecules. The latter class of compound, termed low molecular weight gelators (LMWG) of which 14.11 14.15 are examples, is perhaps of most interest to supramolecular chemists. Perhaps the most well known gels are metal oxide based polymeric materials produced by the sol-gel process. The sol-gel process involves the hydrolysis and polycondensation of monomeric metal salts such as early transition... 

Metal- or metal-oxide-based gas sensors are the most widely used solid-state devices for detecting gases in the environment and atmosphere. The high specific surface areas and uniform mesopores of mesoporous materials will result in a higher probability for a gas to interact with the sensing compounds or sites, which is likely to increase the sensitivity of the material.[310]... 

The building block of each layer of 10 is the spherical icosahedral giant oxidized cluster cage of the Mo72Fe3o type but which now has a reduced metal-oxide-based cluster - the tetrahedral two-electron reduced Keggin [H2PM012040] ion-as nucleus (Figure 8). Like in the layer compound 8, each of the cluster-cluster composites is linked to four others via Fe-O-Fe bonds to form a layer structure. 

The metal oxide based catalysts, i.e. the un-impregnated washcoats, are also forming metal sulfates and sulfites with the SO2 [13, 19]. These compounds are generally less stable at the high temperature, which is required for the CH4 combustion, and hence they were not affected by the SO2. For the H2 and CO their ignition temperatures are well within the stability range for the metal sulfates, and they were also affected. In the case of YAG the effect was an improvement of the catalytic activity, however small, this could probably be contributed to the increased acidity of the catalysts, as have been described for alumina catalysts. 

Another area which was initiated during last year is development of chiral metal oxide based nanomaterials such as chiral Ti02 nanofibres and chiral ZrOj nanotubes. It is anticipated that these chiral metal oxide nanostructures will find very important applications as asymmetric catalysts. In addition the progress in the fabrication of mesoporous silica based chiral nanostructures e.g. helical architectures) should open new opportunities in chiral separation of enantiomeric compounds. 

Ohgi Y, Ishihara A, Matsuzawa K, Mitsushima S, Ota K (2010) Zirconium oxide-based compound as new cathode without platinum group metals for PEFC. J Electrochem Soc 157 B885-B891... 

The reported observations that (i) different, mainly oxide based compounds, which tend to coke deposition, are active for ODH of EB to ST, and that (ii) a characteristic induction period of several hours, during which the coke deposition occius, correlates with an increase of the catalytic activity [2], may indicate that the carbon deposited on the catalyst surface plays an important role in the styrene formation. It was also reported that amorphous carbon activated by oxidation is an active catalyst for the ODH of EB to ST [3]. On the other hand, great interest was paid to carbon nanotubes during last decade due to their stability at high temperatiu es, severe environments, and the possibility to modify them by metal introduction [4-6]. It may be assumed that pure carbon nanotubes, or nanotubes filled with Fe, could be active and stable catalysts for the ODH of EB to ST. In order to test their catalytic activity and to develop a deeper understanding of the relation between carbon structure and its catalytic activity, different types of coibons were used for the ODH of EB to ST. 

In order to confirm this model of adsorption on surface of d" transition metal oxide-based electrodes, we have performed cyclic voltammetry experiments on the compounds LiCo02, LiNi02 (d" oxides), and Li4TisOi2 (d oxide) (Fig. 6.5). 

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