Photocatalytic Properties of WO3/TiO2 Core/Shell Nanofibers prepared by Electrospinning and Atomic Layer Deposition

Core WO3 nanofibers (140-300nm in diameter, several hundred mu m long) are made by a novel, water-based electrospinning process using ammonium metatungstate (AMT) and polyvinylpyrrolidone (PVP) as precursors. TiO2 shells (1.5-20nm) are grown by atomic layer deposition (ALD) using TiCl4 and water at 250 degrees C. The WO3/TiO2 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 WO3/1.5nm TiO2 nanofibers, which have higher activity compared to bare WO3 and Degussa TiO2. Thicker TiO2 layers fill the pores of the nanowires and reduce the specific surface area, weakening the photocatalytic activity.