How porous periodicity of mesoporous materials like TiO2-SBA-15-10 encourages photocatalytic degradation of rhodamine B: a comparative study with aperiodic TiO2-SiO2-aerogel-10

Discovery of new photocatalytic materials that can efficiently degrade organic contaminants is of great interest. In the present work, TiO2 was spatially dispersed over two siliceous mesoporous supports, SBA-15, representing an example of a material with periodic and ordered array of pores and SiO2-aerogel-10, as an example of an aperiodic material with random network of hierarchical pores. The resulting materials, TiO2-SBA-15-10 and TiO2-SiO2-aerogel-10, were characterized comprehensively by several analytical methods and their photocatalytic performance was evaluated by examining the oxidation of rhodamine B dye under visible light irradiation. The adsorption of rhodamine B was enhanced in TiO2-SBA-15-10 in comparison to TiO2-SiO2-aerogel-10. In diffuse reflection spectra (DRS), the presence of Ti4+ in tetrahedral geometry was observed to be higher for TiO2-SBA-15-10 sample. Thus, in the photocatalytic degradation study, a significant enhancement in the oxidation of rhodamine B dye was observed for TiO2-SBA-15-10 in comparison to TiO2-SiO2-aerogel-10. The formation of oxidation intermediates was analyzed by electrospray ionization-mass spectrometry (ESI-MS) indicating degradation of rhodamine B. This study illustrates the importance of the coordination of the Ti4+ in enhancing photocatalytic degradation of model dye pollutants such as rhodamine B.

Automated summary

In this study, new photocatalytic materials were discovered by dispersing TiO2 on two different siliceous mesoporous supports, SBA-15 and SiO2-aerogel-10. The TiO2-SBA-15-10 showed higher efficiency and enhanced adsorption capacity for the oxidation of rhodamine B dye compared to TiO2-SiO2-aerogel-10. The presence of Ti4+ in tetrahedral geometry in TiO2-SBA-15-10 was observed to be higher, explaining its improved photocatalytic performance.