SERS study of Co-doped TiO2 nanoparticles

Single-phase Co-doped TiO2(Co (x) Ti1-x O-2) nanoparticles(NPs) synthesized via a simple sol-hydrothermal method 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 Co2+ ions for the Ti4+ ions. The Co2+ doping increases the defect concentration of Co (x) Ti1-x O-2 NPs. An amount of defects is beneficial to the charge-transfer so as to increase the SERS activities. A possible mechanism of charge-transfer from Co (x) Ti1-x O-2 NPs to molecules was then briefly discussed.