Controlled growth of WO 3 nanostructures with three different morphologies and their structural, optical, and photodecomposition studies

Abstract

Tungsten trioxide (WO 3) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na 2WO 4·2H 2O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH 4) 2Fe(SO 4) 2·6H 2O] or cobalt chloride (CoCl 2·6H 2O) as structure-directing agents. Orthorhombic WO 3 having a rectangular slab-like morphology was obtained when Na 2WO 4·2H 2O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO 3 nanowire clusters and hexagonal WO 3 nanorods were obtained, respectively. The crystal structure and orientation of the synthesized products were studied by X-ray diffraction (XRD), micro-Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and their chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS). The optical properties of the synthesized products were verified by UV-Vis and photoluminescence studies. A photodegradation study on Procion Red MX 5B was also carried out, showing that the hexagonal WO 3 nanowire clusters had the highest photodegradation efficiency. © to the authors 2009.