How porous periodicity of mesoporous materials like TiO 2 -SBA-15-10 encourages photocatalytic degradation of rhodamine B: a comparative study with aperiodic TiO 2 -SiO 2 -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.