Enhanced visible light photocatalytic activity of interlayer-isolated triplex Ag@SiO2@TiO2 core–shell nanoparticles

Herein, we demonstrate the design and fabrication of a well dispersed triplex Ag@SiO2@TiO2 core–shell photocatalyst, which shows enhanced visible light photocatalytic activity due to the plasmonic field of the inner Ag core. The SiO2 interlayer is coated on the Ag core by a sol–gel process to prevent oxidation of Ag and adjusting the plasmonic field. The Ag@SiO2@TiO2 nanoparticles with systematic variation of the SiO2 interlayer thickness of 2, 4, 8, 20 nm and TiO2 shell thickness of 2, 10, 20, 40 nm are prepared. The enhancement of the photocatalytic efficiency increases with decreased SiO2 thickness. Nanoparticles with a 2 nm SiO2 interlayer and a 20 nm TiO2 shell exhibited the best photocatalytic performance, ca. 31 times larger in photocatalytic activity and ca. 38 times larger in photocurrent density than P25 under visible light. A brief mechanism relating the plasmon resonance energy transfer from Ag to TiO2 and scattering is proposed. Such an intriguing photocatalyst may find significant applications in various fields.