Photochemical insights of TiO2 decorated mesoporous SBA-15 materials and their influence on the photodegradation of organic contaminants

• Published in: Microporous and mesoporous materials 2017-11, Vol.253, p.203-214
• Main Authors: Conceição, D.S., Graça, C.A.L., Ferreira, D.P., Ferraria, A.M., Fonseca, I.M., Botelho do Rego, A.M., Teixeira, A.C.S.C., Vieira Ferreira, L.F.
• Format: Article
• Language: English
• Subjects: Fluorescent dye; Mesoporous silica nanoparticles; Photocatalysis; Photochemistry; Titanium dioxide
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2017.07.013

Mesoporous silica, SBA-15, decorated with different amounts of TiO2 (anatase) were prepared by a sol-gel method followed by hydrothermal treatment and calcination, in the presence of a soft template, copolymer Pluronic 123. Tetraethyl orthosilicate (TEOS) was used as the SiO2 precursor and commercially available TiO2 anatase nanoparticles as the supported photocatalyst. The materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), N2 adsorption-desorption isotherms, raman spectroscopy, ground state diffuse reflectance (GSDR), laser induced luminescence (LIL) and X-ray photoelectron spectroscopy (XPS). The zeta potentials of the pure SBA-15, TiO2/SBA-15 substrate and the commercial anatase sample were monitored through a complete range of pH values. All the nanomaterials developed in this work were studied in terms of their photoactivity in the UV range and in the visible range, separately. In the first case, hydroxyl radicals (OH) were confirmed to be the key active oxidizers in the photodegradation of the pesticide amicarbazone in aqueous medium. On the other hand, in the visible range, and following a dye sensitization process via a fluorescent rhodamine-like dye, two different mechanisms could be identified for the formation of the superoxide radical anion, O2−. [Display omitted] •This work presents a full characterization of TiO2 decorated SBA-15 particles.•The structural and photochemical evaluation of the materials was performed.•The formation of both hydroxyl and superoxide anion radicals was assessed.•A fluorescent dye was used as the surface probe in visible excitation conditions.•Amicarbazone was used as the model contaminant following UVA excitation.