Highly sensitively detecting tetramethylthiuram disulfide based on synergistic contribution of metal and semiconductor in stable Ag/TiO2 core-shell SERS substrates

In this study, we successfully constructed Ag/TiO 2 core-shell nanoparticles through an easy wet chemistry method for SERS study. Compared to Ag cores, the Ag/TiO 2 core-shell nanoparticles presented higher SERS sensitivity, owing to a synergistic SERS enhancement arising from electromagnetic field effect of Ag cores and chemical enhancement of TiO 2 shells. Furthermore, uniform TiO 2 shells were able to effectively protect the internal Ag cores against destruction in external environment and thus storage stability of Ag/TiO 2 nanoparticles was prominently improved. The as prepared Ag/TiO 2 core-shell nanoparticles were applied to quantitatively sense tetramethylthiuram disulfide (TMTD) in solution using a portable Raman spectrometer. The results showed that the SERS intensity of 563 cm −1 assigned to S-S stretching mode had a good linear relationship with the concentration of TMTD with the correlation coefficient (R 2 ) of as high as 0.99 and the detection limit of as low as 1.15 × 10 −10 M. Consequently, the prepared Ag/TiO 2 nanoparticles present specially advantage of quantifying S-S groups by SERS, because the TiO 2 shell could act as a spacer between Ag cores and TMTD molecules and keep the S-S bonds intact.