Fabrication of Titanium Dioxide Based Nanofibers Photocatalyst by Electrospinning Technology A Semiconductor Defect and Band Position Engineering for Contaminated Water Treatment

Abstract

The challenge of global environmental pollution, particularly with water newlinecontamination, represents a significant obstacle. Mixed-phase anatase-rutile titanium newlinedioxide (TiO2) has gained recognition as an effective photocatalyst for addressing such newlineissues. However, the underlying mechanisms driving its performance, especially in largescale newlineone-dimensional nanofibers, including aspects of band alignment and defect newlineengineering, are not yet fully understood. This thesis focuses on the fabrication of mixed newlinephase electrospun TiO2 nanofibers with tailored defects near the conduction band. newlineExperimental findings reveal that optimizing band alignment between the rutile and anatase newlinephases, coupled with an upward shift of the band edge, enhances photocatalytic efficiency. newlineThis improvement is attributed to the formation of surface electric dipole layers induced by newlinethe engineered defects. newlineA comprehensive analysis was conducted to explore the effects of polymer newlineconcentration on the crystallinity and phase composition of TiO2 nanofibers, alongside the newlineinfluence of electrospinning solution parameters and ambient conditions. The polymer, newlineparticularly polyvinylpyrrolidone (PVP), was found to play a dual role in the electrospinning newlineprocess: aiding fiber formation through chain entanglements and influencing TiO6 octahedral newlineconfigurations. Surprisingly, the percentage of the anatase phase was found to decrease with newlineincreasing the polymer amount with a fixed annealing temperature. The experimental results newlineshow that carrier polymer polyvinylpyrrolidone is not only involved in fiber formation newlinethrough chain entanglements but plays a significant role in controlling TiO6 octahedral newlineconfigurations and connectivity. More polymers promote edge-sharing between TiO6 rather newlinethan corner-sharing. Hence the importance of optimization of polymer and titanium newlineprecursor concentration ratio was demonstrated with the RhB degradation photocatalytic newlineperformance newline