A multifunctional Ag/TiO2/reduced graphene oxide with optimal surface-enhanced Raman scattering and photocatalysis

A multifunctional Ag/TiO2/reduced graphene oxide (rGO) ternary nanocomposite was prepared by a one-step photochemical reaction with TiO2 and Ag nanoparticles successively deposited on reduced graphene oxide. The structure, morphology, composition, optical, and photoelectrochemical properties of Ag/TiO2/rGO were investigated in detail. Meanwhile, the ternary nanocomposite possessed much higher adsorption capacity to organic dyes compared with bare TiO2 and binary Ag/TiO2, which would help to its use for surface-enhanced Raman scattering detection and photocatalytic degradation. Due to the charge transfer between rGO and organic dyes and enhanced electromagnetic mechanism of Ag, Ag/TiO2/rGO nanocomposites as surface-enhanced Raman scattering substrates demonstrated dramatically improved sensitivity and good uniformity. The detection limit of rhodamine 6G (R6G) was as low as 10(-9)mol/L, and the relative standard deviation values of the intensities remained below 5%. Most importantly, the synergistic coupling effect of three components extended the photoresponse range and accelerated separation of the electron-hole pairs, leading to greatly improved photocatalytic activity under simulated sunlight. The maximum rate constant (k, 0.06243min(-1)) of Ag/TiO2/rGO was 50 and four times higher than that of TiO2 and Ag/TiO2, respectively.