Hybrid mesoporous silicas as platforms for the controlled synthesis of the metalli...
| Full text | |
| Author(s): |
Araujo, M. M.
;
Silva, L. K. R.
;
Sczancoski, J. C.
;
Orlandi, M. O.
;
Longo, E.
;
Santos, A. G. D.
;
Sa, J. L. S.
;
Santos, R. S.
;
Luz, Jr., G. E.
;
Cavalcante, L. S.
Total Authors: 10
|
| Document type: | Journal article |
| Source: | Applied Surface Science; v. 389, p. 1137-1147, DEC 15 2016. |
| Web of Science Citations: | 21 |
| Abstract | |
In this paper, a new synthesis method was proposed to obtain anatase titanium oxide (TiO2) nanocrystals anchored into SBA-15 molecular sieve, as a matrix assigned by the in-situ anchoring (ISA) method. Pure SBA-15 and modified with TiO2 nanocrystals at different Si/Ti molar ratios (R = 75, 50, and 25) were structurally characterized by X-ray diffraction (XRD), Micro-Raman and Fourier Transform infrared (FTIR) spectroscopies. Specific surface area, pore volume and average pore diameter were estimated using both Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, respectively. Morphological aspects of these samples were observed by means of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Optical properties were investigated by ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. XRD patterns, Micro-Raman and FT-IR spectra indicate the TiO2 nanocrystals crystallized in a tetragonal structure anchored into the SBA-15 mesopores. BET and BJH methods prove a large amount of TiO2 nanocrystals were anchored inside of SBA-15 mesopores due to increase in surface area and average pore size of SBA-15 matrix. FE-SEM and TEM images showed the pure SBA-15 has an elongated hexagon-shaped microstructure, and an average size of 7.34 nm for 2D hexagonal mesopores. Moreover, ISA method was able to avoid blocking of mesopores, in addition promotes a significant increasing the impregnation rate of anatase TiO2 nanocrystals in SBA-15 matrix. A growth mechanism was proposed in order to explain the stages involved in the formation of TiO2-SBA mesoporous. UV-vis spectra revealed a dependence of the optical band gap energy (E-gap) with the decreasing of Si/Ti molar ratios. (C) 2016 Elsevier B.V. All rights reserved. (AU) | |
| FAPESP's process: | 12/14004-5 - Investigation of the photoluminescence and photocatalytic properties of pure and Mn, Cu, and Zn-doped BaWO4 and BaMoO4 powders |
| Grantee: | Júlio César Sczancoski |
| Support type: | Scholarships in Brazil - Post-Doctorate |
| FAPESP's process: | 13/07296-2 - CDMF - Center for the Development of Functional Materials |
| Grantee: | Elson Longo da Silva |
| Support type: | Research Grants - Research, Innovation and Dissemination Centers - RIDC |