Influence of titania content on the mesostructure of titania–silica composites and their photocatalytic activity

\Titania–silica composites (TSC) with various Ti/Si ratios were synthesized via sol–gel process using less expensive precursors; sodium silicate solution as a silica source and titanium oxychloride as a titania source. The influence of varying Ti content in the composites was examined by FTIR, SEM, TEM, DTA/TGA, N2 physisorption studies, XRF and XRD. The BET surface area of the raw materials increased with increasing Ti/Si ratio up to 2.9 (461 m2/g) but further increase of Ti content beyond that ratio yielded composites with decreased surface area. The effect of aging evaluated in the sample with Ti/Si = 2.9 revealed that aging the composite for 2 h yields titania–silica powder with the highest surface area (461 m2/g). The FTIR analysis displayed the presence of a vibration band at 945 cm− 1, assignable to hetero linkage of the Si–O–Ti depicting the incorporation of TiO2 into SiO2 to form a composite. Moreover, photodegradation of methyl orange (MO) by the samples calcined at 800 °C showed that the TSC-5-800 (Ti/Si = 5.6) exhibited the highest maximum photocatalytic activity of all the composites.

The SEM micrographs of the calcined titania–silica composites with Ti/Si = 0.7 (a), Ti/Si = 2.9 (b) and Ti/Si = 5.6 (c). (d) TEM micrograph for the sample with Ti/Si = 2.9.Figure optionsDownload as PowerPoint slideHighlights
► TiO2–SiO2 composite with superior properties is synthesized from cheap sources.
► The influence of varying Ti content in the TiO2–SiO2 composites is examined.
► Aging for 2 h yields a composite with the highest surface area (461 m2/g).
► The TSC-5-800 sample exhibits the highest activity of the all composites.