Anatase TiO2 nanocrystals anchored at inside of SBA-15 mesopores and their optical behavior

Autor(es)

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.

• Tipo de documento: Artigo Científico
• Fonte: Applied Surface Science; v. 389, p. 1137-1147, DEC 15 2016.
• Citações Web of Science: 19

Resumo

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)

• Processo FAPESP: 12/14004-5 - Investigação das propriedades fotoluminescentes e fotocatalíticas de pós de BaWO4 e BaMoO4 puros e dopados com Mn, Cu e Zn
• Beneficiário: Júlio César Sczancoski
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/07296-2 - CDMF - Centro de Desenvolvimento de Materiais Funcionais
• Beneficiário: Elson Longo da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs