ore WO 3 nanofibers (140-300 nm in diameter, several hundred mm long) are made by a novel, water-based electrospinning process using ammonium metatungstate (AMT) and polyvinylpyrrolidone (PVP) as precursors. TiO 2 shells (1.5-20 nm) are grown by atomic layer deposition (ALD) using TiCl 4 and water at 2508C. The WO 3 /TiO 2 composite fibers are analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM)-energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Raman spectroscopy (RS), UV-Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The optimal photocatalytic conversion under visible light is reached by the WO 3 /1.5 nm TiO 2 nanofibers, which have higher activity compared to bare WO 3 and Degussa TiO 2 . Thicker TiO 2 layers fill the pores of the nanowires and reduce the specific surface area, weakening the photocatalytic activity.

Abstract:In the present work, core TiO 2 and ZnO oxide nanofibers were prepared by electrospinning, then shell oxide (ZnO, TiO 2 ) layers were deposited on them by atomic layer deposition (ALD). The aim of preparing ZnO and TiO 2 nanofibers, as well as ZnO/TiO 2 and 3 TiO 2 /ZnO nanocomposites is to study the interaction between the oxide materials when a pure oxide fiber is covered with thin film of the other oxide, and explore the influence of exchanging the core and shell materials on their photocatalytic and gas sensing properties.The composition, structure and morphology of the pure and composite nanofibers were studied by SEM-EDX, TEM, XRD, FTIR, UV-Vis and Raman. The photocatalytic activity of the as-prepared materials was analyzed by UV-Vis spectroscopy through decomposing aqueous methyl orange under UV irradiation. The gas sensing of the nanofibers was investigated by detecting 100 ppm NH 3 at 150 and 220 °C using interdigital electrode based sensors.

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