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), TiO 2 nanoclusters were modified inside the pores of SiO 2 core-shell particles instead of the outside. The pore size distribution of SiO 2 core-shell spheres modified with TiO 2 (SiO 2 @ d SiO 2 @TiO 2 ) was analyzed by Barrett-Joyner-Halenda (BJH) method and density functional theory (DFT) method, respectively. The results of the DFT calculations demonstrate that the TiO 2 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 TiO 2 nanoclusters are modified into the pores and the structure of the original SiO 2 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 TiO 2 was measured by XRD. SiO 2 @ d SiO 2 @TiO 2 spheres functionalized with C18 were packed into a stainless steel column. The chemical stability of SiO 2 @ d SiO 2 @TiO 2 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. TiO 2 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.