Titanium oxides, lower

Lithium-titanium-oxide spinels provide a relatively low voltage of 1.5V vs. lithium. They are, therefore, of interest as possible negative electrode materials for lithium-ion cells [161-163] they can be coupled, for example, to Li[Mn2104 (4V vs. Li) to yield a 2.5V lithium-ion cell, or to LixMn02 (3V vs. Li) to yield a 1.5V lithium-ion cell. Although these cells have a voltage lower than that of commercial... 

Fig. 10-27. Energy diagram for a cell of photoelectrolytic decomposition of water consisting of a platinum cathode and an n-type anode of titanium oxide (rutile) of which the Fermi level at the flat band potential is lower than the Fermi level of hydrogen redox reaction (ensc>< = external voltage required for cell reaction to occur S = aqueous solution.

Zrrconium(IV) and hafnium(IV) complexes have also been employed as catalysts for the epoxidation of olefins. The general trend is that with TBHP as oxidant, lower yields of the epoxides are obtained compared to titanium(IV) catalyst and therefore these catalysts will not be discussed iu detail. For example, zirconium(IV) alkoxide catalyzes the epoxidation of cyclohexene with TBHP yielding less than 10% of cyclohexene oxide but 60% of (fert-butylperoxo)cyclohexene °. The zirconium and hafnium alkoxides iu combiuatiou with dicyclohexyltartramide and TBHP have been reported by Yamaguchi and coworkers to catalyze the asymmetric epoxidation of homoallylic alcohols . The most active one was the zirconium catalyst (equation 43), giving the corresponding epoxides in yields of 4-38% and enantiomeric excesses of <5-77%. This catalyst showed the same sense of asymmetric induction as titanium. Also, polymer-attached zirconocene and hafnocene chlorides (polymer-Cp2MCl2, polymer-CpMCls M = Zr, Hf) have been developed and investigated for their catalytic activity in the epoxidation of cyclohexene with TBHP as oxidant, which turned out to be lower than that of the immobilized titanocene chlorides . ... 

At high temperature, Ti02 reacts with reducing agents such as carbon monoxide, hydrogen, and ammonia to form titanium oxides of lower valency metallic titanium... 

The selectivity towards N2 in the photocatalytic decomposition of NO as a function of the coordination number of Ti obtained from EXAFS measurements for various titanium oxide photocatalysts is shown in Figure 3 (Yamashita and Anpo, 2004). The linear dependence observed demonstrates that the lower the coordination number of titanium, the higher the N2 selectivity (Zhang et al., 2001). A similar dependence of CH3OH selectivity on the coordination number of titanium is also observed in the photocatalytic reduction of C02 with H20 (i.e., the... 

Spectral Photoresponses of Carbon-Doped Ti02 Film Electrodes. Raman spectra used to identify disordered carbon in the flame-formed samples in addition to lower nonstoichiometric titanium oxides identified by X-ray diffraction. 314... 

The majority of titanium organometallic chemistry involves complexes in which the titanium is in its highest oxidation state (+4) and cyclopentadienyl see Cyclopenta-dienyl) derivatives serve as ancillary ligands. However, considerable chemistry has also been developed in which the titanium is in the +3 and +2 oxidation state, with lesser amounts of chemistry known for titanium in lower oxidation states (+1, 0). Since the early 1980s, chemists have placed considerable emphasis on the fine-tuning of the stracture and reactivity of titanium organometallic... 

The addition of O2 onto the anchored titanium oxide catalyst led to an efficient quenching of the photoluminescence at 77 K. The addition of N2O also led to the quenching of the photoluminescence with an efficiency lower than that of O2. Such an efficient quenching of the photoluminescence by the addition of O2 or N2O is expected when the emitting sites are dispersed on the support surfaces due to the efficient interaction of the emitting sites with the quencher molecules 168, 212). 

Although strontium is one of the major metal ion constituents in sea water, its concentration of 8.1 mg/1 is about 50 times lower than that of calcium. No procedures are known for a commercial recovery of strontium from sea water. Strontium can be extracted from sea water along with uranium and other elements by hydrous titanium oxide. However, only 120-fold concentration has been reached... 

Loo investigated Raman scattering of electrogenerated iodine on a titanium oxide electrode. He reports signals at 181, 190, and 360 (weak overtone) cm" Also the anti-Stokes transition is seen. The signals were not seen at 488- or 514.5-nm excitation, but only for excitations between 530.9 and 647.1 nm. This strongly indicates resonance scattering. However, that of free iodine is at 515 nm, and the band gap of the oxide is 3 eV (415 nm). Thus one must conclude that the interaction of the iodine with the solid shifts the resonance to lower frequencies. 

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