Hydrophobic TiO₂–SiO₂ composite aerogels synthesized via in situ epoxy-ring opening polymerization and sol-gel process for enhanced degradation activity

TiO₂–SiO₂ composite aerogels composed of an organic-inorganic molecular network were synthesized via an epoxy-ring opening polymerization and sol-gel procedure followed by supercritical drying. The ring opening polymerization and sol-gel reaction were performed using epoxy-functionalized (3-glycidyloxypropyl)trimethoxysilane and amine-functionalized 3-aminopropyltriethoxysilane. This process was followed by hydrolysis and condensation of methyltrimethoxysilane (MTMS) and titanium butoxide (TBO) in the presence of oxalic acid as a catalyst. The results revealed that the TBO:MTMS molar ratio plays an important role in enhancing the crystallinity, porosity, and surface area of the prepared composite aerogels. Anatase titania was obtained with the as-prepared supercritical dried aerogels and the photocatalytic performance of the aerogels was evaluated via the degradation of a methylene blue textile dye under ultraviolet-light irradiation. The results demonstrated that the TiO₂–SiO₂ composite aerogel catalyst can yield 87% degradation with a high reaction constant (k = 1.18 × 10⁻¹ min⁻¹). This approach provides a new method of synthesizing TiO₂–SiO₂ composite aerogel photocatalysts.