Structural, morphological, optical and photocatalytic properties of Ag decorated graphene oxide-TiO2 films

Highlights: • Nanosized metalic Ag decorated graphene oxide (GO)-TiO2 films were prepared. • The structural, morphological and photocatalytic properties were investigated. • The synergy effect for Ag decorated GO-TiO2 films was shown. • GO-Ag optimally modified TiO2 films performed the higher photocatalytic activity. Nanoparticulate graphene oxide (GO)-TiO₂ films combined with Ag nanoparticles to construct a modified photocatalyst were prepared using a sol-gel and spin coating technique. Metallic Ag islands with average grain sizes from 23 to 51 nm via controlling the deposition time of 20 ~ 90 s in the sputtering process were found to be uniformly distributed on the surface of the GO-TiO₂ films. Characterization was carried out upon the films using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-Vis) absorption spectrophotometry. The UV-Vis spectroscopy concluded the band gap reduction of TiO₂ films (3.1 eV) as the GO loading amount reachers to its maximum value of 13% (2.93 eV). Chemical states of Ti, Ag, C and O of the films were investigated by XPS. The photocatalytic performance of the films was evaluated by the amount of decomposition of methylene blue as a function of irradiation time. The results showed that Ag-GO-TiO₂ films modified with the most optimal GO (5%) and Ag (20 s) condition displayed highly enhanced photocatalytic activity (about twice improvement) compared with pure TiO₂ films, indicating their potential application in water purification