Characteristics of the hydration layer structure in porous titania-silica obtained by the chemical vapor deposition method
The titania-silica samples prepared by means of the chemical vapor deposition technique on the basis of mesoporous silica with different contents of grafted TiO{sub 2} were investigated. For these samples, the chemical shifts of adsorbed water, the thickness of the hydrate shell, and the free surface energy of aqueous medium were measured using the {sup 1}H NMR method. It was estimated that the chemical shift ({delta}) of the absorbed water is between 2.6 and 3.8 ppm. For the sample with 7.7 wt % TiO{sub 2}, the signal of strongly bonded water with {delta} {equals} 1.3 ppm is present in the spectra of adsorbed water. Probably this signal is caused by the water molecules, which form the electron-donor complexes with Ti atoms. With increasing TiO{sub 2} concentration, the free surface energy ({Delta}G{sub {Sigma}}) at first decreases from 160mJ/m{sup 2}, for the initial silica gel, to 90mJ/m{sup 2} for the sample containing 4.5 wt % TiO{sub 2} and then increase up to 130 mJ/m{sup 2} for the sample with 7.7 wt % TiO{sub 2} concentration. The values of {Delta}G{sub {Sigma}} for porous and nonporous materials were compared.
- Research Organization:
- Maria Curie-Sklodowska Univ., Lublin (PL)
- OSTI ID:
- 20006403
- Journal Information:
- Langmuir, Vol. 15, Issue 24; Other Information: PBD: 23 Nov 1999; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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