Recyclable Au–TiO₂ nanocomposite SERS-active substrates contributed by synergistic charge-transfer effect

Abstract

In this study, Au deposited TiO₂ (Au-TiO₂) nanocomposites were prepared by photocatalytic reduction of Au species (HAuCl₄) on TiO₂ nanoparticles (NPs) and served as efficient SERS-active substrates. The observed considerable SERS enhancement of 4-MBA molecules on Au-TiO₂ NPs compared with that on pure TiO₂ NPs can be attributed to the synergistic contribution of semiconductors and metals by the charge-transfer mechanism from the substrate to the molecule. In the preparation of Au-TiO₂ nanocomposites, the photo-reduction time and concentration of HAuCl₄ have an important influence on the SERS enhancement effect of the composite substrate. Moreover, for the recycle of substrates, the photocatalytic experiment of Au-TiO₂ nanocomposites was carried out. The results show that these nanocomposite substrates are characterized by a self-cleaning property and can be repeatedly used in SERS experiments without losing their activity and with high stability.