Titania surface modification

In a similar way, a well-adhered surface modification of BC fibers can be achieved with Ti(>2 nanoparticles (with a diameter of about 10 nm) by the hydrolysis of titanium tetraisopropanolate adsorbed onto the fibers. It was observed that the titania-coated surface appears to be dense and have low porosity and to consist of near-spherical grains. By washing with sodium carbonate solution, the TiC>2 films were not removed during neutralization. It seems that the particles have formed strong interactions with BC. The coated membranes showed substantial bactericidal properties under UV radiation and white light (containing a small fraction of UV) conditions, too. This effect is caused by the photocatalytic destruction of the bacterial cells. 

Upon stirring a suspension of titania powders in an aqueous solution of H2[PtCl6] in the dark, different maximum amounts were adsorbed. For the anatase hydrate and anatase/rutile samples TH (Kronos) and P25 (Degussa), there were taken up 4.0% and 1.1%, respectively, whereas only traces were adsorbed onto the rutile material Aid. The almost four times larger amount adsorbed by TH corresponds with the about four times larger surface area as compared to P25 (vide infra). Subsequent heat treatment at 200 °C afforded the desired photocatalyst (21). Surface modification may be performed also by simple grinding with PtCU, but the resulting powders are of lower photocatalytic activity and less stability (18,20). 

Pressure-induced phase transformations for anatase-Ti02 were monitored by Raman spectroscopy.40 Raman spectroscopy was used to characterise rutile titania nanocrystalline particles with high specific surface areas.41 Micro-Raman spectra were used to follow surface transformations induced by excimer laser irradiation of Ti02.42 There was Raman spectroscopic evidence for modification of a titania surface by attached gold nanoparticles.43... 

However, other derivatization techniques have been developed that are suitable for application to any surface and therefore can be used for the modification of the surfaces of these three oxides. In the following, we will first discuss the properties of the surfaces of alumina, titania, and zirconia, and then proceed to examine some surface modification techniques that have been used to date. 

Attempts have been made to design packings with an expanded pH compatibility compared to silica, but with a hardness comparable to silica. Other inorganic carriers such as alumina, titania, and zirconia have been explored. Indeed, their hardness matches that of silica, and being impervious to small molecules, they also exhibit the same advantageous mass-transfer properties as silica. However, no simple surface modification techniques are available as yet that match the silanization chemistry used for silica. Therefore, polymeric coatings have been used, which then in turn exhibit inferior mass-transfer behavior. 

For alumina, titania, and zirconia, there exists as yet no covalent bonding chemistry that is equivalent to the silanization technique used for silica. Although attempts have been made to silanize these other oxides, the hydrolytic stability of these phases does not match up to the hydrolytic stability of the support itself. Therefore alternative surface modification tet ques have been developed that do not rely on the attachment of the modifier to the surface. The coating can be simply insoluble in the intended mobile phases, or a crosslinked coating can be formed that stretches like a net around the skeleton of the particle. Both techniques are, in principle, independent of the nature of the substrate and can be applied to all inorganic or polymeric packings. 

Lopez, M. C., Ortiz, G. F., Gonzalez, J. R, Alcantara, R., and Tirado, J. L. (2014). Improving the performance of titania nanotube batteiy materials by surface modification with lithium phosphate, ACS Appl Mater. Interfaces, 6, pp. 5669-5678. 

Fig. 1 Surface modification of Ti02 nanoparticles for the preparation of PVA-titania nanohybrid materials (adapted after [21], with permission from Elsevier)...

Pietron J J, Rolison D R (2001) ElectrochemicaUy induced surface modification of titanols in a nanoglued titania aerogel composite film. J Non-Cryst Solids 285 13-21... 

Efficient intracellular delivery of the anticancer drug camptothecin (CPT) by hollow silica/titania nanoparticles has been reported [114]. Monodispersed hollow nanoparticles (about 50 nm) were prepared by titania coating of Stober silica particles followed by silica dissolution and redeposition in an ammonia solution (Figure 11.13). Surface modification of these particles with an antibody herceptm, a... 

Ionic liquids can be covalently bound to the surface of Ti02 in order to obtain a modification of VB and CB of titania and finally enhance the absorption of visible... 

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