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A heterostructure photocatalyst including metallic silver (Ag), gold (Au) in the form of nanoparticles (NPs) and titanium oxide (TiO2) nanofibers were fabricated using a combination of photodeposition and electrospinning techniques. In this procedure, electrospun TiO2 nanofibers were decorated by plasmonic Ag and Au NPs on the surface of nanofibers which were generated via photochemical reduction process. The synthesized Ag-Au/TiO2 nanocomposites which were considered as a favorable candidate for enabling the more access to visible-light in photocatalytic performance were subsequently characterized by field emission scanning electron spectroscopy (FESEM), transmission electron spectroscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultra-violet-visible (UV–vis) spectroscopy. UV–vis studies indicate the extension in the absorption region of composite toward the visible-light range have been occurred through the loading metallic nanoparticles into the TiO2 structure. Microscopic assessments in addition to EDS revealed that metallic NPs deposited on the surface of the fibers through photochemical reduction process. It was found that, the ratio of utilized Ag/Au in the final composite can significantly enhance the photocatalytic efficiency. It was suggested that introduction of the proper amount of noble metal NPs into the TiO2 matrix leads to the notable enhancement of visible-light decomposition of rhodamine B (Rh. B) as a model dye.

The heterogeneous titanium oxide-reduced graphene oxide-silver (TiO2/RGO/Ag) nanocomposites were successfully prepared by incorporation of two dimensional (2D) RGO nanosheets and spherical silver nanoparticles (NPs) into the 1D TiO2 nanofibers. The novel TiO2/RGO/Ag nanocomposites were synthesized by loading TiO2 nanofibers, prepared via electrospinning technique, on the RGO/Ag platform. The resulting nanocomposites have been characterized using various techniques containing transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and ultra-violet-visible (UV–vis) spectroscopy. Microscopic studies clearly verified the existence of TiO2 nanofibers with Ag NPs on the surface of RGO sheet and formation of TiO2/RGO/Ag nanocomposites. Moreover, the results of UV–vis spectroscopy demonstrated that TiO2/RGO/Ag nanocomposites extended the light absorption spectrum toward the visible region and significantly enhanced the visible-light photocatalytic performance of the prepared samples on degradation of rhodamine B (Rh. B) as a model dye. It was found that, incorporation of 50 µl RGO/Ag into the TiO2 nanofibers lead to a maximum photocatalytic performance. Also, the improvement of the inactivation of Escherichia coli (E. coli) bacteria under visible-light irradiation was revealed by introduction of RGO/Ag into the TiO2 matrix. The significant enhancement in the photo and bio-activity of TiO2/RGO/Ag nanocomposites under visible-light irradiation can be ascribed to the RGO/Ag content by acting as electron traps in TiO2 band gap.

In the present work, iron-functionalized TiO2 nanofibers have been successfully synthesized by an electrospinning system and the resulting nanofibers were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and ultra-violet-visible spectroscopy. Microscopic studies revealed that TiO2 nanofibers with average diameters of ~60 to 65 nm were formed during the electrospinning process while their diameters increased to ~85 to 90 nm by iron functionalization. Moreover, the photocatalytic activities of pristine and iron-functionalized TiO2 nanofibers were measured by photodegradation of methyl orange (MO) as a model dye under visible-light irradiation. It was found that iron-functionalized TiO2 nanofibers extended the light absorption spectrum toward the visible region and noticeably improved the photodegradation of MO under visible-light irradiation. Furthermore, there is an optimum amount of FeCl3 to reach to the highest photocatalytic performance of iron-functionalized TiO2 nanofibers under visible-light.