One‐Step Direct Synthesis of SiO2–TiO2 Composite Nanoparticle Assemblies with Hollow Spherical Morphology

Abstract

SiO2–TiO2 composite nanoparticle assemblies with or without alkyl surface modification and bearing a higher‐order hollow spherical morphology were successfully synthesized by a simple, rapid, one‐pot, and single‐step solvothermal method using a precursor solution consisting of n‐octyl‐Si(OMe)3 or Si(OEt)4, Ti(OiPr)4, o‐phthalic acid, and acetic acid in methanol. The addition of acetic acid is essential for a high yield of nanoparticle assemblies with hollow spherical morphology and a high content of Si. The Si/Ti atomic ratio in the SiO2–TiO2 composite nanoparticle assemblies was easily controlled by changing the Si/Ti atomic ratio in the precursor solutions. The TiO2 nanoparticles exhibited good dispersibility in a polar solvent (methanol), while the n‐octyl‐modified SiO2–TiO2 composite nanoparticle assemblies were readily dispersed in a nonpolar solvent (toluene). Thus, the hydrophilic–lipophilic balance of the SiO2–TiO2 nanoparticle assemblies with hollow spherical morphology was directly controlled by the one‐pot and single‐step solvothermal method.