Doping TiC

For pure Ti02> the q.y. is higher, for the more concentrated suspension ho wever for the case of both iron-doped TiC>2, the higher q.y. is obtained for the lower concentration of catalyst. The differences can be explained in terms of differences in particle size of the catalysts. Recent results by Navio et al. 

Many approaches have been taken to prepare colloidal doped semiconductor nanocrystals. For example, hot-injection methods have been used to synthesize colloidal Mn2+-doped CdSe (47, 48), ZnSe (49), and PbSe (50) colloidal nanocrystals. Colloidal ZnO DMS-QDs doped with Co2+, Ni2+, and Mn2+ have been prepared by low-temperature hydrolysis and condensation (51-54). Sol-gel methods have been used to prepare colloidal doped TiC>2 (55-57) and Sn02 (58-62) nanocrystals. Inverted micelle methods have been used for preparation of a range of doped II-VI sulfide DMS-QDs at low temperatures (63-68). A high-temperature lyothermal single-source method was used to synthesize Co2+- and Eu3+-doped CdSe nanocrystals (69, 70). Autoclaving has occasionally been used to induce crystallization at lower temperatures than reached under atmospheric pressures while retaining colloidal properties, for... 

Measured for carbon-doped TiC>2 films with Xe-lamp irradiation at 40 mW/cm2. However, see text. 213... 

Yagi I, Ishida T, et al. 2004. Electrocatal)tic reduction of oxygen to water at Au nanoclusters vacuum-evaporated on boron-doped diamond in acidic solution. Electrochem Commun 6 773-779. 

Although the role of rare earth ions on the surface of TiC>2 or close to them is important from the point of electron exchange, still more important is the number of f-electrons present in the valence shell of a particular rare earth. As in case of transition metal doped semiconductor catalysts, which produce n-type WO3 semiconductor [133] or p-type NiO semiconductor [134] catalysts and affect the overall kinetics of the reaction, the rare earth ions with just less than half filled (f5 6) shell produce p-type semiconductor catalysts and with slightly more than half filled electronic configuration (f8 10) would act as n-type of semiconductor catalyst. Since the half filled (f7) state is most stable, ions with f5 6 electrons would accept electrons from the surface of TiC>2 and get reduced and rare earth ions with f8-9 electrons would tend to lose electrons to go to stabler electronic configuration of f7. The tendency of rare earths with f1 3 electrons would be to lose electrons and thus behave as n-type of semiconductor catalyst to attain completely vacant f°- shell state [135]. The valence electrons of rare earths are rather embedded deep into their inner shells (n-2), hence not available easily for chemical reactions, but the cavitational energy of ultrasound activates them to participate in the chemical reactions, therefore some of the unknown oxidation states (as Dy+4) may also be seen [136,137]. 

The mechanism of generation of the mobile charge carriers follows that described in the previous two sections. Donor doping is expected to result in ra-typc thermistors. The situation in which Fe203 is doped with TiC>2, analogous to the situation outlined above for TiC>2-doped Cr203, provides an example. The favored mechanism is the formation of electrons, comparable to Eq. (8.1) ... 

Write defect equations for (a) TiC>2 doped with A1203 (b) Ti02 doped with Nb2Os (c) Mn304 doped with NiO (d) MgO doped with Cr203 and (e) M Os doped with Fe203. 

Another option to lower the Ru losses is to dope the anode coatings with IrO2, which has been shown [53, 54] to markedly decrease the Ru corrosion rate during electrolysis in NaCl solutions. This would minimise the surface depletion of Ru, as shown by the SIMS analysis of the TiC>2 + RuC>2 + IrCU coatings (Fig. 5.19), and thus extend the operating life of the anodes. 

Segura J, Ventura R, Jurado C. 1998. Derivatization procedures for gas chromatographic determination of xenobio-tics in biological samples, with special attention to drugs of abuse and doping agents. J Chromatogr B 713 61. 

Effect of titania modification. TiC>2 was modified by deposition of platinum or by p-and n-type doping with heterovalent cations. 

Earlier work on nanoparticle-doped chiral smectic-A (SmA ) and chiral smec-tic-C (SmC ) phases including some intriguing electro-optic effects in ferroelectric SmC phases were summarized in two earlier reviews [1, 2],... 

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