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

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.