Micro-Raman and photoluminescence analysis of composite vanadium oxide/poly-vinyl acetate fibres synthesised by electro-spinning

Composite vanadium oxide (VOx)-based fibres were synthesised by the electro-spinning method combined with conventionalsol–gel processing using polyvinyl acetate (PVAc) as a polymeric binder and vanadium oxytriisopropoxide as a vanadiumoxide precursor. The microstructure and composition of as-spun and calcined (300–500 C) VOx–PVAc fibres were systematicallyinvestigated by scanning electron microscopy, thermogravimetry, reflectance infrared Fourier transform, micro-Ramanspectroscopy and photoluminescence in view of their possible use in gas sensor fabrication. The comparative discussion ofthe characterization results indicates that V2O5–PVAc fibres are obtained. Calcination gradually removes PVAc and promotesstructural rearrangement with consequent fibre-morphology changes. With increasing calcination temperature, the crystallinitydegree of V2O5 improves and a more oxygen-deficient substoichiometric surface layer forms. Calcination at 400 Cpreserves the fibre integrity. Indeed, fibres calcined at this temperature appear as the most suitable ones for use as the activelayer in gas-sensing devices.