TiC>2 thin films

Liu, Z. H., Huan, S. Y., Liang, 1. H., Shen, G. L. and Yu, R. Q. (2006), Molecularly imprinted TiC>2 thin film using stable ground-state complex as template as applied to selective electrochemical determination of mercury. Talanta, 68(4) 1120-1125. 

The most widely used precursors for the CVD-synthesis of TiC>2 thin films are TiCl4 and titanium isopropoxide. The chemical nature of the precursors has been shown to have a direct influence on the properties of the deposited Ti02 films, as reported by Evans and coworkers (2006). The existence of oxygen in titanium isopropoxide molecules makes it possible for an intramolecular reaction to take place. 

The lone pair is produced intrinsically by the sp-orbit hybridization of O and N. The number of lone pairs in a tetrahedron follows the rule of 4-n , where n is the valence value of the electronegative additive. Vibration of the dipole induced by the lone pairs should be detectable by Raman spectroscopy in the frequency range below 1,000 cm . A Raman experimental survey (HeNe laser, normal incidence) from the following specimens confirmed this expectation [12]. Figure 6.2 shows Raman spectra of (1) AI2O3 and Ti02 powders (2) thin films of Ti nitride (TiN) and amorphous carbon nitride and, (3) films of amorphous carbon (a-C) and Ti carbide (TiC). As anticipated, the lone-pair features of the oxides (n = 2) are stronger than those of the nitrides (n = 3) while no such features can be resolved from carbides (n = 4). The appearance and the relative intensity of these low-frequency Raman features support the prediction and the rules of 4-n for lone-pair formation as well. 

Sol-gel-derived films can also serve to provide protective coverings, flat outer layers for microrough surfaces, or thin dielectric layers. Spin-on glasses have been developed for all these applications. Some films can change color under an applied EMF (e.g., TiC>2 turns blue at 2 V, while... 

The semiconductors n-TiC>2 and n-WO3 have been sensitized with thin films (100-250 A) of MPc (M = Mg, Zn, TiO, Co, Fe, C1A1, H2)81 and have been shown to effect the photo-oxidation of I-, [Fe(CN)6]4 , hydroquinone and [Fen(EDTA)]2. Photocurrents were proportional to the light... 

S.B. Kim, S.C. Hong, Kinetic study for photocatalytic degradation of volatile organic compounds in air using thin film TiC>2 photocatalyst, Appl. Catal. B Environ. 35 (2002) 305-315. 

The photoelectrochemical activity inherent in thin films of aggregated cyanine dyes permits them to act as the spectral sensitizers of wide bandgap semiconductors [69]. It is seen from Fig. 4.14 that the photoelectrochemical behaviour of semiconductor/dye film heterojunctions fabricated by deposition of 200 nm-thick films of cyanine dyes on the surface of TiC>2 and WO3 electrodes, bears close similarity to that of semiconductor electrodes sensitized by the adsorption of dye aggregates. Thus, both anodic and cathodic photocurrents can be generated under actinic illumination, the efficiency of the photoanodic and photocathodic processes and the potential at which photocurrent changes its direction being dependent on dye and semiconductor substrate [69]. 

An example of recent achievement in this area is a flexible, thin film Cu(In,Ga)Se2 solar cell deposited on a titanium foil, which was combined with a TiC>2 photocatalyst layer and modified by a niobium-doped titanium oxide front electrode to function as a photoelectrochemical tandem cell/membrane for a direct light-driven hydrogen evolution from an aqueous solution [48], Under illumination with UV/vis light, the system produced up to 0.052 pLH2/scm2 (e.g. the hydrogen formation rate was approximately 7,250 pmol/h g relative to the amount of TiC>2 used). Several aspects of the operating principles of the photoelectrochemical devices, the materials requirements, main bottlenecks, and the various device concepts (in relation to H2... 

Neumann B, Bogdanoff P, Tributsch H. TiC>2-protected photoelectrochemical tandem Cu(In,Ga)Se2 thin film membrane for light-induced water splitting and hydrogen evolution. J Phys Chem C. 2009 113 20980-9. 

Fig. 22 Effect of TiC>2 addition on the hydrophobicity of a highly hydrophobic thin film during outdoor exposure the numbers refer to TiC>2 concentration (wt%)...

A novel method of a photocatalytic lithography based on a photogeneration of Pd nanoparticles in thin films of Pd2+-doped nanostructured titania followed by an electroless nickel plating is proposed. The possibility of a generation of both negative and positive metal patterns employing TiC>2 Pd2+ photolayers is discussed in terms of a dispersity of a photoproduced Pd nanophase and its catalytic activity towards an eletroless nickel deposition. 

Horiguchi et al. carried out diffusion bonding of TiC with Mo and reported a kinetic expression for the diffusion between the two materials. Extrapolating their results to the present conditions of heat treatment, it is expected that a diffusion layer of at least 5 m thickness is formed at the TiC/Mo interface possibly resulting in a reaction product such as Mo 2 C. Lack of diffusion or reaction layer between the TiC and Mo in the sprayed specimens may be because sprayed Mo particles were covered with thin oxide film. Further study is necessary to confirm this hypothesis, however. 

---