Synthesis of TiO2/ZnFe2O4 composite nanofibers by co-spinning for photocatalytic applications
Photocatalysis can be summarized as the light-induced redox reaction prompted by a catalyst. Charge separation due to absorption of energy equal to the bandgap energy of the semiconductor leads to the formation of electrons and holes in the conduction and valance band of the semiconductor, respectively. The photo-induced electrons can directly reduce the dye molecules or produce a superoxide radical anion to serve the purpose. Similarly, holes generated in the valance band oxidize the dye or produce hydroxyl radicals for oxidation. The most utilized semiconductor for photocatalysis is TiO2. It is eco-friendly, cost-effective, non-toxic, resistant to corrosion, thermally and chemically stable, and degrades organic dyes. However, only 4% of the total solar energy (UV light) is captured by TiO2 owing to its large bandgap (3.2eV). Several strategies have been designed to tackle this issue, such as doping with metals or non-metals, constructing heterojunctions, loading a metal, and introducing carbon-based material. Zinc ferrite has a bandgap of 1.9 eV and has functional properties such as magnetic behavior, stability, regeneration, and photocatalysis. Yet, it is not able to stabilize the photogenerated charge carriers. In this research, co-spinning is employed to make TiO2/ZnFe2O4composite nanofibers to design a catalyst activated by visible light and having stabilized charge carriers. Co-axial electrospinning, a subset of the co-spinning technique, can result in core-shell nanofibers which can potentially have better stability and improved properties for various applications. However, the formation of core-shell nanofibers requires optimization of the process conditions especially the flow rates of the two solutions. The spinneret in co-axial electrospinning comprises two nozzles that are aligned concentrically. The core and shell solutions simultaneously flow through the separate nozzles at different flow rates controlled by separate pumps. Parameters such as voltage, collecting distance, and viscosity of the solutions can be monitored to get the nanofibers with desired characteristics. This study intends to synthesize core-shell nanofibers of TiO2 and ZnFe2O4 with TiO2 as the shell and ZnFe2O4 as the core through the coaxial electrospinning technique by tuning and optimizing the electrospinning parameters. The heterostructure nanofibers synthesized will be tested for photocatalytic applications.
- Dr. Salman Noshear Arshad (Supervisor)
- Dr. Habib-ur-Rehman (Thesis Committee Member/Evaluator)
- Dr. Ali Rauf (Thesis Committee Member/Evaluator)