Improved surface-enhanced Raman scattering properties of TiO2 nanoparticles by Zn dopant

In this paper, pure and Zn-doped TiO2 nanoparticles (NPs) with various content of Zn were prepared by a sol-hydrothermal method and were employed as active substrates for surface-enhanced Raman scattering (SERS). On the 3% Zn-doped TiO2 substrate, 4-mercaptobenzoic acid(4-MBA) molecules exhibit a higher SERS intensity by a factor of 6, as compared with the native enhancement of 4-MBA adsorbed on undoped TiO2 NPs. Moreover, the higher SERS activity was still observed on the 3% Zn-doped TiO2 NPs at temperature even up to 125 °C. These results indicate that an appropriate amount of Zn doping can improve the SERS performances of TiO2 SERS-active substrates. The introduction of Zn dopant can enrich the surface states (defects) of TiO2 and improve the separation efficiency of photo-generated charge carriers (electrons and holes) in TiO2, according to measurements of X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and photoluminescence, which are responsible for the influence of Zn dopant on the improved SERS performances of TiO2 NPs. Copyright