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.

Photocatalysts are the most important technology in air pollution removal and the detoxification of organic materials. Doping and complexation are among the most used methods to improve the efficiency of photocatalysts. Titanium dioxide and zinc oxide nanomaterials are widely used materials for photocatalysts and the degradation of toxic materials. Their mixed structure can be fabricated by many methods and the structure affects their properties. Nanofibers are efficient materials for photocatalysts due to their vertically formed structure, which improves the charge separation of photoelectrons. We fabricated them by an electrospinning process. A precursor consisting of titanium 4-isopropoxide, zinc acetate dihydrate and polyvinylpyrrolidone was used as a spinning solution for a mixed structure of titanium dioxide and zinc oxide with different molar ratios. They were then calcined, crystallized by heat treatment and analyzed by thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM) and energy-dispersive spectroscope (EDS). After annealing, the average diameters of the Ti–Zn complex oxide nanofibers were 237.6–278.6 nm with different salt ratios, and multiple crystalline structures were observed, namely TiO₂, ZnO, ZnTiO₃ and Zn₂TiO₄. We observed the photocatalytic performance of the samples and compared them according to the photodegradation of methylene blue. The methylene blue concentration decreased to 0.008–0.650 after three hours, compared to an initial concentration of 1, with different metal oxide structures.

In South Korea, efforts to reduce carbon dioxide emissions and environmental impacts from the perspective of life cycle assessment (LCA) are important because of the implementation of zero-energy building certification for public buildings and the promotion of net-zero policy. Therefore, it is critical to develop cement alternatives with low embodied energy and less environmental impact. In this study, the applicability of “highly sulfated calcium silicate cement (HSCSC),” an eco-friendly binder developed by our research team, was investigated. Its basic properties and environmental footprint reduction effects were examined in comparison with ordinary Portland cement (OPC) and Portland blast furnace slag cement (PBSC). The environmental impacts of the HSCSC were analyzed using the LCA method. The results confirmed that HSCSC can be considered an excellent alternative to conventional OPC or PBSC in certain areas as an eco-friendly binder that can reduce carbon dioxide emissions and environmental impacts. Moreover, compared to OPC and PBSC, the probability of HSCSC affecting the human body is extremely low. The results of this study may contribute to the development and practical use of cements that minimize climate impacts, as well as improve the efficacy of future research on embodied energy saving.