A redox-active support for the synthesis of Au@SnO 2 core-shell nanostructure and SnO 2 quantum dots with efficient photoactivities.

A defect pyrochlore-type Sn 1.06 Nb 2 O 5.59 F 0.97 (SnNbOF) nano-octahedron is used as a redox-active support for fabricating Au@SnO 2 core-shell and SnO 2 quantum dots at room temperature without the use of organic species or foreign reducing reagents. Gold (Au) and SnO 2 components were obtained through an in situ redox reaction between the HAuCl 4 and reductive Sn 2+ ions incorporated in SnNbOF. The composition and morphology of the resulting nanocomposites (denoted as Au-SnNbOF) could be controlled by adjusting the Au/SnNbOF ratio. The Au-SnNbOF nanocomposites exhibited efficient photoactivities for methyl orange (MO) degradation under the visible light irradiation ( λ > 420 nm), during which the MO was almost completely degraded within 8 min. Among all the samples, the 5wt% Au-SnNbOF nanocomposite had the highest rate constant (0.43 min -1 ), which was 40 times higher than that of the blank SnNbOF.