Synthesis of Au@TiO2 core-shell nanoparticles with tunable structures for plasmon-enhanced photocatalysis
Plasmonic metal-semiconductor nanocomposites, especially those with core-shell nanostructures, have received extensive attention, as they can efficiently expand the light absorption and accelerate the electron-hole separation thus improve the photocatalytic efficiency. However, controlled synthesis and structure manipulation of plasmonic metal-semiconductor nanocomposites still remain a significant challenge. Herein, a simple and universal method has been developed for the preparation of plasmonic Au@TiO2 core-shell nanoparticles. Using such a method, uniform TiO2 shells are successfully coated on Au nanoparticles with various morphologies including nanorod, nanocube, and nanosphere, and the thickness and crystallinity of the TiO2 shell can be simply tuned by adjusting pH value and thermal treatment, respectively. Furthermore, the influence of the morphology of the Au core, as well as the thickness and crystallinity of the TiO2 shell, on the photocatalytic performance of Au@TiO2 towards the photodegradation of methylene blue are systematically explored. It is found that Au@TiO2 NPs with nanorod morphology and crystalline TiO2 shells display the best performance, which is 5 times higher than that of bare Au nanoparticles. This work provides a facile strategy for the fabrication of plasmonic core-shell nanostructures that show excellent performance in plasmon-enhanced photocatalysis.