Titanium dioxide has excellent chemical, electrical, and optical properties, as well as good chemical stability. For that reason, it is widely used in many fields of study and industry, such as photocatalysts, organic solar cells, sensors, dental implants, and other applications. Many nanostructures of TiO₂ have been reported, and electrospinning is an efficient practical technique that has a low cost and high efficiency. In various studies on improving performance, the researchers created nanofibers with suitable microstructures by changing various properties and the many process parameters that can be controlled. In this study, PVP/TiO₂ nanofibers were fabricated by the electrospinning process. The diameters of the nanofibers were controlled by various parameters. To understand the effects on the diameter of the nanofibers, various process parameters were controlled: the molecular weight and concentration of the polymers, deionized water, applied voltage, fluid velocity, and concentration of titanium precursor. The average diameter of the PVP nanofibers was controlled in a range of 42.3 nm to 633.0 nm. The average diameter of the PVP/TiO₂ nanofibers was also controlled in a range of 63.5 nm to 186.0 nm after heat treatment.

TiO₂ nanofibers have high chemical stability and high strength and are applied to many fields such as air pollution sensors and air pollutant removal filters. ZnO nanofibers also have very high absorptivity in that air and are used as germicides and ceramic brighteners. TiO₂/ZnO nanofibers, which have a composite form of TiO₂ and ZnO, were fabricated and show higher photocatalytic properties than existing TiO₂. The precursor, including zinc nitrate hexahydrate, polyvinyl acetate, and titanium isopropoxide, was used as a spinning solution for TiO₂/ZnO nanofibers. Electrospun TiO₂/ZnO nanofibers were calcined at 600 °C and analyzed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). The average diameter of TiO₂/ZnO nanofibers was controlled in the range of 189 nm to 1025 nm. XRD pattern in TiO₂/ZnO nanofibers have a TiO₂ anatase, ZnO, Ti₂O₃, and ZnTiO₃ structure. TiO₂/ZnO nanofibers with a diameter of 400 nm have the best photocatalytic performance in the methylene blue degradation experiments and an absorbance decrease of 96.4% was observed after ultraviolet (UV) irradiation of 12 h.

To improve sensing performance, the metal oxide semiconductor (MOS) gas sensor needs to have amuch bigger specific surface area in the active layer, lower power and higher sensitivity. TiO₂ nanotube arrays were used for the active layer of a MOS gas sensor because they are chemically stable and electrically semi conductive. To obtain clean, open window nanotubes, two-step anodic oxidation was conducted. The diameter of the window and length of the nanotubes were 60 nm and 5.5 μm, respectively. TiO₂ nanotube arrays were transplanted by the SnO₂ adhesion layer. The SnO₂ adhesion layer had a nanoparticle diameter of 30 nm and a thickness of 4 μm. The sensitivity increased with the CO gas concentration and was 0.061 at 300 ppm. The response was very quick. A power consumption of 80 mW was measured with an effective gas detection performance.