Improvement and Red Shift toward Visible Spectrum of TiO_2 Nanofibers through Doping by Fe_2O_3 and Nitrogen

摘要

TiO_2 has many applications as photocatalyst, photo/electrochromic device, solar cell and sensors. It has been activated only by UV light. In this research we have been investigated on the effect of adding Fe_2O_3 nanoparticles and N on the absorption spectrum in order to increase their activity and shift toward visible light for TiO_2 nanofibers. We used electrospining method to fabricate nanofibers. Sol gel for spinning pure nanofibers contains Titanium tetraisopropoxide (C_(12)H_(28)O_4Ti), acetic acid (CH_3COOH), ethanol (C_2H_5OH) and PVP (C_6H_9NO-12 wt.% ). Then we used Fe_2O_3 nanoparticle (size: 20-40 nm, purity: 98%) and HNO_3 acid for doping. Among Fe_2O_3-doped samples, the 2.1 wt% Fe_2O_3 indicated the highest activity for visible light, while with HNO_3, excellent photo-catalyst activity obtained at 1.5wt% Fe_2O_3 and 5 wt% HNO_3(purity :65%). The final solutions were stacked into the syringe and joined to a high voltage DC supply. A piece of glass stacked on aluminum foil was used as collector. Finally nanofibers calcined at 500°C. FESEM, XRD and Spectrophotometry techniques were employed to deliberation nanofibers. Diameter of the fibers was approximately 100 nm (anatase: 77%). The Fe_2O_3-TiO_2 and Fe_2O_3-N-TiO_2 nanofibers indicated respectively 50% and 80% growth in absorption intensities under visible light irradiation compared to pure nanofiber and absorption spectrum peak moved towards larger wavelengths (70 and 100nm) when TiO_2 Doped with Fe_2O_3 and Fe_2O_3-N.