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

Abstract

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.