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Shedding light on precursor and thermal treatment effects on the nanostructure of electrospun TiO2 fibers

2016; Elsevier BV; Volume: 7; Linguagem: Inglês

10.1016/j.nanoso.2016.05.003

2352-5088

Sara Morandi, Claudio Cecone, Giulia Marchisio, Pierangiola Bracco, Marco Zanetti, Maela Manzoli,

Conducting polymers and applications

Electrospinning technique was employed for the synthesis of different TiO2 samples, starting from titanium oxysulfate and titanium n-butoxide (TNBT) as precursors. The electrospun fibers, obtained after optimization of starting solutions, were either calcined in air at 450 °C or treated in 50 mbar of pure oxygen at 450 °C. The main goal was to obtain TiO2 fibers constituted by crystallites with size lower than 10 nm (size largely reported in literature for this kind of synthesis) in the anatase form. Before thermal treatment, the morphology of the fibers was characterized by Scanning Electron Microscopy (SEM); after thermal treatment TiO2 morphological and structural properties were determined by Transmission Electron Microscopy (TEM) as well as by high resolution (HR-) TEM and X-ray Diffraction (XRD). TiO2 prepared with TNBT precursor and treated in oxygen at 450 °C gave the best results in terms of crystalline phase (pure anatase) and particle size (about 5 nm). Moreover, HR-TEM analysis of the fibers obtained from TNBT before thermal treatment revealed that the precursor crystallization occurred already at room temperature during the electrospinning process, giving rise to nucleation germs for the subsequent growth of TiO2 crystallites during the thermal treatment. On the contrary, samples prepared by electrospray and by simple solvent evaporation at room temperature of the solution with the same TNBT precursor did not give the same promising results in terms of crystalline phase and particle size.