Effects of preparation parameters on the characteristics of SiO2- and CoxOy-modified-TiO2 colloids prepared by hydrolysis of titanium alkoxide

• Published in: Journal of sol-gel science and technology 2020-06, Vol.94 (3), p.607-615
• Main Authors: Brichkov, Anton S., Brichkova, Victiria Yu, Paukshtis, Evgeniy A., Chen, Yu-Wen, Kozik, Vladimir V.
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Chlorides; Colloids; Composites; Derivatives; Diffusion coefficient; Glass; hybrids and solution chemistries; Hydrochloric acid; Hydrolysis; Inorganic Chemistry; Materials Science; Nanotechnology; Natural Materials; NMR; Nuclear magnetic resonance; Optical and Electronic Materials; Optimization; Original Paper: Sol-gel; Parameter modification; Particle size; Photon correlation spectroscopy; Raman spectroscopy; Rheological properties; Silicon dioxide; Siloxanes; Sols; Spectrum analysis; Synthesis; Tetraethyl orthosilicate; Titanium; Titanium dioxide
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-019-05139-4

A series of SiO 2 -, and Co x O y -modified-TiO 2 colloids prepared by hydrolysis of titanium alkoxide were synthesized. The effects of concentrations of water, acid, cobalt chloride, and tetraethoxysilane on the characteristics of colloids were investigated. The rheologic characteristics of the sols were characterized by liquid state 29 Si nuclear magnetic resonance (NMR), Raman spectroscopy, and photon correlation spectroscopy. It was found that an increase in the acid concentration from 1 to 60 mM resulted in a decrease of the particle size from 17 to 9 nm, while the diffusion coefficient increased with twofold. The presence of water shortened the formation time of sol, and the specific concentration of hydrochloric acid stabilized the colloid system. The presence of Co(II) chloride enhanced the hydrolysis rate of tetraethoxysilane and the condensation rate of hydroxy derivatives. In contrast, Ti(IV) tetra-n-butoxide showed the opposite effect, slowing these processes and decreasing the degree of condensation of siloxane chains. The results of this study can be used to optimize the composition of stable homogeneous solutions to synthesize TiO 2 , TiO 2 –SiO 2 , TiO 2 –Co x O y , and TiO 2 –SiO 2 –Co x O y sols. Time dependence of the kinematic viscosity of the FFS containing butanol, 100 mM TBT, 30 mM CoCl 2 , 20 mM HCl, and H 2 O. Traces 1 and 2 correspond to [H 2 O] = 230 and 830 mM, respectively. Highlights The optimum condition to synthesize TiO 2 , TiO 2 –SiO 2 , TiO 2 –Co x O y , and TiO 2 –SiO 2 –Co x O y sols was developed. An increase in the acid concentration resulted in a decrease of the particle size. The presence of Co(II) chloride enhanced the hydrolysis rate of tetraethoxysilane and the condensation rate of hydroxy derivatives. The presence of Ti(IV) tetra-n-butoxide showed the opposite effect, suppressed the hydrolysis rate of tetraethoxysilane and the condensation rate of hydroxy derivatives.