Preparation of SiO2@TiO2 composite nanosheets and their application in photocatalytic degradation of malachite green at emulsion interface

Abstract

In this work, SiO2@TiO2 composite nanosheets (CNS) was prepared with Janus SiO2 nanosheets as a template and employed as a photocatalyst in the degradation of malachite green dye (MG). At first, Janus SiO2 nanosheets with hydrophilic amino groups and hydrophobic phenyl groups tethered on each side were derived from a combination of emulsion interface induced self-assembly and sol-gel method. Subsequently, TiO2@SiO2 CNS was prepared through a hydrolysis-precipitation process owing to the interaction of tetrabutyl titanate (TBT) with amino groups on the surface of Janus SiO2 nanosheets. Photocatalytic degradation of MG under UV light was selected as a model reaction to evaluate the photocatalytic activity of TiO2@SiO2 CNS in an aqueous solution and at an emulsion interface at room temperature. The results showed that TiO2@SiO2 CNS has good catalytic activity and reusability for degradation of MG dye in the aqueous solution. More importantly, a much higher degradation efficiency for MG dye including a higher degradation rate and a shorter irradiation time were achieved with TiO2@SiO2 CNS served as an emulsifier and a photocatalyst simultaneously at emulsion interface, presumably due to a larger reactive area. The better catalytic performance of TiO2@SiO2 CNS in the emulsion interface elucidates an alternative strategy for conventional heterogeneous reactions.