Enhanced optical and photocatalytic properties of Ag quantum dots-sensitized nanostructured TiO2/ZnO heterojunctions

Ag quantum dots (Ag QDs) sensitized TiO2 nanorod arrays (NRAs)/ZnO nanoparticles (NPs) heterojunctions were fabricated by a three-step method and investigated as photocatalysts. Experimental results showed that the novel material exhibited enhanced optical properties and a high degradation rate (for methyl orange) under UV light (109% compared to bare TiO2 NRAs). The high rate was attributed to an increase in the separation of electrons-holes induced by the introduction of the ZnO NPs and the localized surface plasmon resonance (SPR) of Ag QDs. The degradation mechanism was elucidated based on the band structure. It is suggested that the TiO2/ZnO/Ag nanostructure developed in our work can provide a new platform for the design of highly efficient photocatalysts.