A New Route to Size and Population Control of Silver Clusters on Colloidal TiO2 Nanocrystals

Formation of hybrid Ag-TiO2 nanocrystals (NCs) in which Ag clusters are uniformly deposited on individual TiO2 NC surface has been achieved by using hydrophobic surfactant-capped TiO2 NCs in combination with a photo deposition technique. The population of Ag clusters on the individual TiO2 NC surface can be controlled by the degree of hydrophobicity (e.g., the number of vacant sites) on the TiO2 NC surface while their size may be altered simply by varying irradiation time. A reversible change in color of the resulting hybrid Ag-TiO2 NCs is induced by alternating UV light and visible-light illumination; however, the size and population of Ag clusters on TiO2 NCs are almost unchanged. Furthermore, these materials also exhibit much higher photocatalytic performance as compared to that of Ag supported on commercial TiO2-P25.