Templating Quantum Dot to Phase-Transformed Electrospun TiO₂ Nanofibers for Enhanced Photo-Excited Electron Injection

Abstract

We report on the microstructural crystal phase transformation of electrospun TiO 2 nanofibers generated via sol−gel electrospinning technique, and the incorporation of assynthesized CdSe quantum dots (QDs) to different phases of TiO 2 nanofibers (NFs) via bifunctional surface modification. The effect of different phases of TiO 2 on photo-excited electron injection from CdSe QDs to TiO 2 NFs, as measured by photoluminescence spectroscopy (PL) is also discussed. Nanofiber diameter and crystal structures are dramatically affected by different calcination temperatures due to removal of polymer carrier, conversion of ceramic precursor into ceramic nanofibers, and formation of different TiO 2 phases in the fibers. At a low calcination temperature of 400 o C only anatase TiO 2 nanofiber are obtained; with increasing calcination temperature (up to 500 o C) these anatase crystals became larger. Crystal transformation from the anatase to the rutile phase is observed above 500 o C, with most of the crystals transforming into the rutile phase at 800 o C. Bi-functional surface modification of calcined TiO 2 nanofibers with 3-mercaptopropionic acid (3-MPA) is used to incorporate as-synthesized CdSe QD nanoparticles on to TiO 2 nanofibers. Evidence of formation of CdSe/TiO 2 composite nanofibers is obtained from elemental analysis using Energy Dispersive X-ray spectroscopy (EDS) and TEM microscopy that reveal templated quantum dots on TiO 2 nanofibers. Photoluminescence emission intensities increase considerably with the addition of QDs to all TiO 2 nanofiber samples, with fibers containing small amount of rutile crystals with anatase crystals showing the most enhanced effect.

Guanine oxidation signal enhancement in single strand DNA with polyacrylonitrile/polyaniline (PAN/PAni) hybrid nanofibers

“…The char amounts for PAN and PAN/PAni composite NFs with different PAni content were 44.75, 36.21, 40.08, and 41.93% for pure PAN, low, mid, and high content of PAni in PAN NFs samples, respectively. Decomposition of PAN is in agreement with the literature . Although the residuals of the PAN/PAni composite NFs were less than the pure PAN NFs, the results appeared to fluctuate.…”

“…When NFs are used for biosensor application, better signal capacity from the target process can be obtained due to high specific surface area. Electrospinning is a promising technology for producing NFs from variety of materials including polymers, ceramics, and even metals . Electrospun NFs have been produced and used for various applications such as filtration, sensors, and protective clothing .…”

“…Polymer NFs such as poly(vinyl alcohol), polyacrylonitrile (PAN), polyethylenoxide, and polyester have been produced via solution and melt electrospinning processes. Ceramic NFs such as titanium dioxide (TiO 2 ), zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), lithium cobalt oxide (LiCoO 2 ), and so forth, have been produced via electrospinning of the precursor materials by following an appropriate calcination process.…”

Highly photoactive heterostructures of PbO quantum dots on TiO2

“…4 Several research efforts have been directed towards modifying TiO 2 to exhibit visible light photocatalytic activity. Since the report by Honda and Fujishima, 1 TiO 2 based material have been extensively utilized with regard to photodegradation of environmental pollutants.…”

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

“…Tissue scaffolds 1 , composite materials 2 , optical communications 3 , and conductive hybrid materials 4 are areas of research utilizing specialized polymer fibers. Conventional methods for fiber fabrication include melt extrusion, spinning, drawing, casting and electrospinning.…”