TiO2/DMS-1 disordered mesoporous silica system: Structural characteristics and methylene blue photodegradation activity

Disordered mesoporous silica (DMS-1) material was synthetized using nonionic surfactant as liquid template and tetraethyl orthosilicate (TEOS) as silica precursor. The x%TiO2/DMS-1 systems (x = 7–35 wt.% of TiO2) were synthetized by the post-synthesis grafting of the calcined DMS-1 substrate. Characterization by several techniques (N2 adsorption–desorption isotherms, X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), micro-Raman spectroscopy and X-ray photoelectron spectroscopy (XPS)) indicates that the x%TiO2/DMS-1 systems consist of TiO2 anatase nanoparticles located on the external substrate surface. The photocatalytic behavior of these samples was evaluated in the photodegradation of methylene blue (MB) dye carried out under ultraviolet light illumination at room temperature. An important enhancement in the photocatalytic activity of the x%TiO2/DMS-1 with respect to unsupported TiO2 (P-25) sample was observed. The MB photodegradation activity increased linearly with an increase of the TiO2 loading from 7 to 35 wt.%. The highest activity of the 35%TiO2/DMS-1 sample was explained as due to the enhancement of anatase surface exposure with respect to the other photocatalysts.

It has been observed that decoration of DMS-1 material with TiO2 nanoparticles leads to an increase in degradation of methylene blue and this increase was lineal with TiO2 loadings. Interestingly, all composite photocatalysts exhibited larger photoactivity than unsupported TiO2 commercial sample. The better catalytic performance of photocatalyst containing the largest TiO2 loading are explained in terms of the combined factors such as a largest surface exposure of anatase TiO2 phase, preservation of a high surface area, a large amount of the surface hydroxyl groups, and a larger accessibility of photooxidative sites.Figure optionsDownload as PowerPoint slideHighlights
► Mesoporous TiO2/DMS-1 matrices as photocatalysts.
► Photocatalysts for the degradation of methylene blue.
► Particle size and photocatalytic properties were found to depend on the TiO2 loadings.
► TiO2/DMS-1 composite is more active than pure TiO2.
► Textural characteristics of mesoporous materials have great influence for the catalytic activity.