Preparation of sensitive and recyclable porous Ag/TiO2 composite films for SERS detection

Porous Ag/TiO2 composite films were prepared by spin coating of titania on normal glass slides and subsequent photochemical deposition of silver nanoparticles (AgNPs). The films were characterized by XRD and FESEM to reveal micro structural and morphological differences between films obtained under varied conditions. The SERS properties of these films were investigated using aqueous crystal violet (CV) as probe molecules. The results indicate that the content of polyethylene glycol (PEG) and photoreduction time had significant influences on both the microstructure and SERS performance of Ag/TiO2 films. The highest SERS sensitivity that allowed as low as 10(-10) M aqueous CV to be detected, was achieved with the PEG(C4H9O)(4)Ti molar ratio being 0.08% and with 30 min of UV irradiation. With this film a linear relationship was established through experiment between SERS intensity and CV concentration from 10(-10) to 10(-5) M, which could be used as a calibration curve for CV concentration measurement. In addition, the film could be reused as a SERS substrate for up to four times without significantly losing SERS sensitivity if a simple regeneration was followed. It is visualized that the Ag/TiO2 film on glass has potentials for being developed into a practical SERS substrate with high sensitivity and good reusability. (C) 2015 Elsevier B.V. All rights reserved.