Photocatalytic Destruction of Methylene Blue on Ag@TiO 2 with Core/Shell Structure

Abstract

A series of Ag@TiO 2 catalysts with core-shell structure were successfully synthesized by a sol-gel method. The samples were prepared by a sol-gel method using silver nitrate, hydrazine, cetyltri-methylammonium bromide and titanium tetra-isopropoxide as the starting materials. The cata-lysts were characterized by ICP-MS, XRD, TEM, HRTEM and XPS. The results indicated that the sil-ver core was in metallic state and the TiO 2 shell was in anatase state. The size of Ag nanoparticles in core was about 5 and 10 nm, and the shell size of titanium dioxide was 10 and 20 nm. The core was single crystalline Ag nanoparticle and the shell was made up of many TiO 2 nanoparticles. The photocatalytic activity of Ag@TiO 2 was much higher than that of bare TiO 2 . Large amounts of hy-droxyl groups were present on the surface of TiO 2 . The catalysts which were treated by hydro-thermal method had the higher lattice oxide percentage and higher photocatalytic activities. The core-shell structure can prevent Ag from aggregation.