Growth and characterization of sodium-tungsten oxide nanobelts with U-shape cross section

A simple method for synthesis of Na0.65WO3 nanobelts by using sodium, as a catalyst, in soda-lime glass substrate was reported. The synthesized product was characterized and analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and ultraviolet-visible spectrophotometery. According to SEM observations, nanobelts with U-shape cross section grew between sodium-tungsten oxide islands. The thickness, width, and length of nanobelts were measured <100 nm, between 300 nm-3 μm and 5-20 μm, respectively. In addition, it was observed that some of the nanobelts were constituted from nanowires. Based on XPS analysis, more than 70% of the film surface was in W6+ chemical state. XRD analysis determined that the sample was mainly composed of cubic Na0.65WO3 phase with strong (0 1 1) and (0 0 1) diffraction peaks. Optical transmission and reflection of the sample in the visible and near-infrared wavelengths were measured around 15% and 2%, respectively.