Anatase TiO2 nanoparticles with controllable crystallinity as a substrate for SERS: improved charge-transfer contribution

Abstract

In this paper, TiO₂ nanoparticles (NPs) in the anatase phase were synthesized by a very simple sol-hydrothermal method with the assistance of H₂SO₄. And importantly, the crystallinity and the surface defects (surface state) of anatase TiO₂ NPs can be regulated and controlled by this means for improving their SERS performances. The 4-MBA molecule adsorbed on 0.14 mL-H₂SO₄–TiO₂ NPs exhibits the highest SERS enhancement, as compared with the native enhancement on unmodified TiO₂ NPs. The introduction of H₂SO₄ not only enriches the surface defects of anatase TiO₂ and the adsorption site, but also improves the separation efficiency of photo-generated carriers, which all can promote the TiO₂-to-molecule charge transfer and are mainly responsible for the improved SERS performances.