SERS Study of Co-doped TiO2 Nanoparticles

Single-phase Co-doped TiO2（CoxZil_xO2） nanoparticles（NPs） synthesized via a simple sol-hydrothermal me- thod were used as surface-enhanced Raman scattering（SERS） substrates. Interestingly, it was found that SERS signals were enhanced greatly compared to those of pure TiO2 nanoparticles when an amount of Co2＋ ions were doped into the TiO2 lattice. Detailed results clearly show that Co element as Co2＋ was incorporated into the TiO2 lattice and the defects were created due to the substitution of Coz＋ ions for the Ti4＋ ions. The Co2＋ doping increases the defect concentration of CoxTil_xO2 NPs. An amount of defects is beneficial to the charge-transfer so as to increase the SERS activities. A possi- ble mechanism of charge-transfer from CoxTi1-xO2 NPs to molecules was then briefly discussed.