Controlled Growth of WO3 Nanostructures with Three Different Morphologies and Their Structural, Optical, and Photodecomposition Studies

Tungsten trioxide (WO3) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na2WO4 center dot 2H(2)O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH4)(2)Fe(SO4)(2)center dot 6H(2)O] or cobalt chloride (CoCl2 center dot 6H(2)O) as structure-directing agents. Orthorhombic WO3 having a rectangular slab-like morphology was obtained when Na2WO4 center dot 2H(2)O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO3 nanowire clusters and hexagonal WO3 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 WO3 nanowire clusters had the highest photodegradation efficiency.