Controlled Growth of WO3Nanostructures with Three Different Morphologies and Their Structural, Optical, and Photodecomposition Studies

Abstract

Tungsten trioxide (WO3) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na2WO4·2H2O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH4)2Fe(SO4)2·6H2O] or cobalt chloride (CoCl2·6H2O) as structure-directing agents. Orthorhombic WO3having a rectangular slab-like morphology was obtained when Na2WO4·2H2O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO3nanowire clusters and hexagonal WO3nanorods 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 WO3nanowire clusters had the highest photodegradation efficiency.

Promoted Hexagonal Tungsten Bronzes as Selective Catalysts in the Aerobic Transformation of Alcohols: Glycerol and Methanol

“…1A), the diffraction patterns could be assigned to the basic hexagonal tungsten bronze (HTB) structure (JCPDS: 85-2460) in all catalysts studied. Moreover, depending on the precursor used in the synthesis procedure, smaller changes in the intensity of some of the diffraction lines can be observed, which can be related to changes in their morphologies [23]. On the other hand, an additional diffraction peak at 2Ɵ= 25.4°, as minority, is observed for WTiO sample (Fig.1A, pattern b), which is characteristic of TiO2 anatase (JCPDS: 89-4921).…”

The performance of silver modified tungsten oxide for the removal of 2-CP and 2-NP in sunlight exposure: Optical, electrochemical and photocatalytic properties

“…5b. (Rajagopal et al, 2009;Boulova and Lucazeau, 2002). A marked decrease in the intensity of all peaks, especially the peaks at 806.23 and 716.5 cm -1 , for all the Ag + impregnated catalysts, verified the engagement of singly charged surface oxygen by Ag + forming W-O-Ag type surface entities.…”

Hybrid nanocomposites with enhanced visible light photocatalytic ability for next generation of clean energy systems

“…[85] Complementary, characteristic peaks around 284.6 and 287.0 eV were observed for the r-GO-based hybrids and were attributed to C1s of the C-C and the C-O respectively (Figure 3b), [48] further confirming the decoration of the nanoparticles. Analyses also showed that the W atoms were in the formal valence band +6, [78] with the observed binding energy peaks at around 35.8 and 37.8 eV being associated with spin-orbit splitting of the W 4f7/2 and W 4f5/2 respectively (Figure 3c). [88] Lastly, in the O core level XPS spectrum (Figure 3d), the 530.8 eV peak corresponding to the O1s [89] showed no changes in all the samples being investigated, thus indicating that Pt coating and r-GO modification, while changing the surface chemical/physical properties of the hybrids did not affect their crystalline structure.…”

“…[77] Raman spectroscopy confirmed the generation of the r-GO-based hybrid materials; specifically, peaks around 810 cm -1 and 710 cm -1 which were attributed to the stretching of the O-W-O bonds, as well as peaks at 328 cm -1 and 270 cm -1 which were related to the bending vibration of the W-O-W bonds were noted. [78] Peaks below 200 cm -1 were also observed and were generally associated with the vibrations in the lattice modes of the WO3-based nanoparticles, while the D peak around 1350 cm -1 was related to the disorder induced in the carbon (C) structure by the photoreduction of the r-GO surface. Complementary, the G peak around 1600 cm -1 was associated with sp 2 C vibration.…”