Polycrystalline Titania

Following the general approach illustrated in Figure 2.6 we attempted to elucidate the mode of interfacial deposition and the local structure of the deposited title species on the titania surface [51]. The system was studied at 25 °C, pH range 6.0-7.5, metal concentration range 10 — 2 x 10 M and ionic strength I = 0.1 N. Polycrystalline titania rich in anatase (Degussa P25) has been used. 

Redmond G, Fitzmaurice D (1993) Spectroscopic determination of flatband potentials for polycrystalline titania electrodes in nonaqueous solvents. J Phys Chem 97(7) 1426-1430... 

Interest in the composition and structure of submonolayer metal oxide deposits on metals has developed as a consequence of growing evidence that such deposits influence the adsorptive and catalytic properties of the substrate metal [see for example ref. (1)]. In particular, it has been shown that titania deposited on a Ni(l 11) (2) surface and on the surface of Pt and Rh foils (3.41 will enhance the activity of the metal for CO hydrogenation. Similar results have also been reported for niobia deposited on a Pt foil (5). Hie present paper discusses the characterization of titania overlayers deposited on the surface of a polycrystalline Rh foil and a Rh(lll) surface. 

Temperature-programmed desorption (TPD) under ultra-high vacuum conditions of CO and from polycrystalline nickel surfaces containing varying amounts of titania showed that the effects of titania are short-ranged. 

The fact that E-states are not observed on the titania-containing surface does not necessarily suggest a weaker interaction between H-adatoms and adsorbed CO at reaction conditions. Indeed, the catalytic importance of the low-temperature E-states has not been demonstrated, since there is no detectable difference in the methanation rate for Ni(lll), Ni(100), and polycrystalline Ni (1 6, 1 7), surfaces which exhibit markedly different coadsorption behavior with respect to the E-states. 

The relationship between film thickness and measurable vibrational Raman band intensities for strongly scattering titania films shown in Figure 8 suggests that polycrystalline films thicker than a. 0.10 micrometer are necessary in order to observe... 

Rutile. The most common form of TITANIUM OXIDE (q.v.) sp. gr. 4.26. It occurs in the beach sands of Australia, Florida and elsewhere used as an opacifying agent in enamels and glazes. Rutile is also used in the production of titania and titanate dielectrics pure rutile has a dielectric constant of 89 perpendicular to the principal axis and 173 parallel to this axis the value for a polycrystalline body is 85-95 at 20°C. 

The photocatalytic N-allg lation of aniline by alcohols has been obtained over Ti02 (see Sec 1.1.1, p. 167). Photocatalitic oxidation of tri-methylamine has been studied in an annular reactor. The selective oxidation of amines to imines with aerial ojgrgen as the ultimate oxidant has been obtained by titania photocatalysis. The oxidation of triethy-lamine over niobium dioxide has been studied spectroscopically and computationally and homo and heterocoupling of benzylamine and alcohols on polycrystalline CdS have been reported. The role of photochemistry in formation and destruction of nitrosodimethylamine has been reviewed. Visible light photooxidative cyclization of amino alchols yields 1,3-oxazines. Various arylamines have been converted into heterocycles in the presence of TiOa nanopowder. ... 

The integration of nanoMOFs onto surfaces has attracted major interest over the last few years, as it enables facile incorporation of MOF properties (e.g., porosity, magnetism, and luminescence) into functional metallic, metal oxide, and organic substrates as well as into porous alumina and titania supports. This method enables production of MOF thin films and membranes (or SURMOFs) with various compositions and controllable parameters (thickness and pore size, functionahties, and orientation). Direct deposition is a straightforward way to form polycrystalline MOF films it involves dip-coating... 

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