Controlled manipulation of TiO₂ nanoclusters inside mesochannels of core-shell silica particles as stationary phase...

Based on a detailed study of the hydrolysis process of tetrabutyl orthotitanate (TBOT), TiO₂ nanoclusters were modified inside the pores of SiO₂ core-shell particles instead of the outside. The pore size distribution of SiO₂ core-shell spheres modified with TiO₂ (SiO₂@dSiO₂@TiO₂) was analyzed by Barrett-Joyner-Halenda (BJH) method and density functional theory (DFT) method, respectively. The results of the DFT calculations demonstrate that the TiO₂ nanoclusters are always first formed in bulk solution and then enter the pores. By regulating the rate of hydrolysis of TBOT, almost all of the TiO₂ nanoclusters are modified into the pores and the structure of the original SiO₂ core-shell sphere is hardly affected. The morphology of the particles was characterized by scanning electron microscopy and transmission electron microscopy. The crystal phase of TiO₂ was measured by XRD. SiO₂@dSiO₂@TiO₂ spheres functionalized with C18 were packed into a stainless steel column. The chemical stability of SiO₂@dSiO₂@TiO₂ spheres under alkaline was tested by flushing of a mobile phase at pH 13 for 7 days. The efficiency of the column after the alkali solution treatment still reaches 98,430 plates m^-1, which is only about 1.6% lower than that before the alkali solution treatment. A series of basic and acidic analytes were also separated on the column. Graphical abstract TiO₂ nanocrystals were coated into the pore of core-shell silica spheres. The prepared particles were packed into the column and separation performance up to 98,430 plates per meter was achieved.