Fabrication and photoactivity of short rod-shaped mesoporous SiO2@TiO2 composites with TiO2 shell

Abstract

This paper presents an improved strategy for synthesizing short rod-shaped mesoporous SiO₂@TiO₂ composites containing a TiO₂ shell by using short rod-shaped mesoporous SiO₂–polyglycidyl methacrylate (PGMA)–polyoligo(ethylene glycol)methyl ether methacrylate (PEGMA) as a template and tetrabutyl titanate (TBT) as a titanium source. SiO₂–PGMA-b-PEGMA rods were initially fabricated through grafting GMA and EGMA onto the surface of the halogen functional group of mesoporous SiO₂ using activators regenerated by electron transfer-atom transfer radical polymerization. TBT was hydrolyzed with the PEGMA chain through hydrogen bonding. The rod-shaped mesoporous SiO₂@TiO₂ structure was finally acquired through calcination. Characterization results indicated that the amphiphilic block copolymer was grafted onto the mesoporous SiO₂ surface. Moreover, the TiO₂ samples existed only in the anatase phase, and the prepared SiO₂@TiO₂ exhibited bimodal nanoporous structures. The synthesized short rod-shaped mesoporous SiO₂@TiO₂ materials demonstrated higher specific surface area and absorption rate than samples prepared from non-mesoporous or unmodified rod-shaped SiO₂. These characteristics effectively enhanced the photocatalytic activity of the composite. The photocatalytic activity of the fabricated composite was then tested on rhodamine B photodegradation.