Research upon Cu-Doping Contents in TiO2 Nanoparticles Incorporated onto Cellulose Nanofibers for Dye Removal and Self-Cleaning Applications

Cu-doping contents in the TiO2 lattice structure were studied to show the effects on the crystal structure, morphology, and photocatalytic activity of TiO2 nanoparticles and thus composite cellulosic nanofibrous membranes. Pristine and copper-doped TiO2 nanoparticles were synthesized using the sol–gel technique, a wet chemical method with the advantages of low synthesizing temperature, uniform nanosize distribution, and purity. The as-synthesized semiconductor nanoparticles were first tested with the dye removal process and then impregnated onto electrospun cellulose nanofibers (CL nanofibers) to acquire modified nanofibers with self-cleaning properties. The as-prepared composite CL nanofibers consisting of doped and undoped TiO2 nanoparticles were characterized by various techniques, such as field emission scanning electron microscopy, transmission electron microscopy, UV–vis, X-ray diffraction, Fourier transform infrared spectroscopy, and tensile tests. The copper-doped TiO2 molar ratio in the nanocomposite was found to possess a pronounced impact on the dye removal and self-cleaning effects under the visible light spectrum, whereas TiO2 is highly effective under specific UV-light irradiation. Optical measurements and dye decomposition showed that the Cu-doped TiO2 nanocomposite was optimized at a 1% molar ratio by the copper-doping concentration regarding dye removal and self-cleaning applications under the visible light range.