Tungsten-Based Catalysts for Environmental Applications (original) (raw)
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Experimental data on synthesis and characterization of WO3/TiO2 as catalyst
Data in Brief, 2019
WO 3 /TiO 2 is a composite photocatalyst that is being widely used in heterogeneous photocatalysis because it presents better photocatalytic properties than TiO 2. For example, the probability of recombination of the electron/hole pairs is diminished and a more range of the solar spectrum is used for its excitation. However, this depend of variables such as tungsten oxide concentration, calcination temperature and synthesis method. This work is focused in establish the effect of WO 3 on the morphological and structural characteristics of TiO 2. WO 3 /TiO 2 was synthesized by sol-gel method at different calcination temperatures and at different concentrations of tungsten oxide. The surface area, the possible transition between valence band and conduction band, particle size, elemental analysis and crystallography were examined through the BET, DRS, SEM-EDS and XRD analysis.
Tungsten oxide multifunctional nanostructures: Enhanced environmental and sensing applications
Materials Chemistry and Physics, 2019
Tungsten oxide (WO 3) nanostructures of controlled morphology were successfully synthesized by hydrothermal method. The size, shape and crystal structure were tuned by varying amount of precursor and structure directing agent. TEM and XRD measurements confirm the formation of hexagonal and monoclinic nanostructures. The synthesized WO 3 nanostructures exhibit excellent photocatalytic and sensing properties. The photocatalysis was performed at room temperature by varying three different organic dyes i.e. Methyl Blue (MB), Methyl Orange (MO) and Rhodamine B (RhB) under UV irradiation. The photocatalytic efficiencies were optimized considering the effects of catalyst amount, dye concentration, calcination temperature and pH. Moreover, the WO 3 nanostructures reveal excellent electrocatalytic properties for sensing of H 2 O 2 and L-Cysteine. The WO 3 /GCE modified electrode shows highly reproducible sensitivity of 4.99 µA µM-1 cm-2 and 0.301 µA µM-1 cm-2 for H 2 O 2 and L-Cysteine, respectively. Moreover, the modified electrode exhibits a low detection limit of about 0.5 µM and wide linear detection range from about 0.5 to 50µM for H 2 O 2 and a low detection limit of about 3 µM and wide linear detection range from about 3 to 50µM for L-cysteine, respectively. Our results demonstrate that WO 3 nanostructures with multifunctional properties can be employed for remediation of environmental issues and sensing applications.
Japanese Journal of Applied Physics, 2014
To develop a simple fabrication method for a highly efficient visible-light-driven photocatalyst, we investigated the photocatalytic ability of tungsten oxide (WO3) nanoparticles prepared on substrate surfaces by the metal–organic decomposition (MOD) method. Using this method, the diameter of WO3 nanoparticles was varied from 70 to 250 nm by simply adjusting the baking temperature. The WO3 nanoparticles prepared under optimal conditions showed that their photocatalytic ability under visible light is 10 times higher than that of TiO2 fabricated by the MOD method under optimal conditions.
REVIEW : Synthesis of nanoparticles and nanocomposite of WO3
2021
Tungsten oxide (WO 3 ) is a semiconductor that can be used in a wide variety of applications such as semiconductor gas devices, electronic devices, and photocatalysts. WO 3 can be proposed as a substitute for TiO 2 because it has a narrow bandgap property, which makes this material active in the UV-Vis spectrum. The purpose of writing this paper is to conduct a literature review on the synthesis of WO 3 nanoparticles and nanocomposites using a review method on 50 literature from 2000 to 2020 by reviewing several methods such as hydrothermal methods, sol-gel, low-temperature hydrolysis and, water-in-oil microemulsion in sucrose esters, calcination, flame-assisted spray pyrolysis, ultrasonic, and microwave irradiation. Besides, it is also reviewed based on several starting materials such as sodium tungsten dihydrate, AMT (ammonium metatungsten), ammonium tungstate hydrate, H 2 WO 4 , phosphotungsten acid, Cl 6 W, and W powder.
Applied Catalysis B-environmental, 2008
WO 3 /TiO 2 composite nanoparticles have been synthesized by dissolving W and Ti precursors in a suitable solvent and spraying into a high temperature acetylene-oxygen flame using a reactive atomizing gas. Particles with controlled W:Ti ratios were produced at various flow rates of precursor solution and the resulting powders were characterized by Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and attenuated total reflection infrared (ATR-IR) spectroscopy. Two-dimensional coordinatively unsaturated wolframyl species were well dispersed on the TiO 2 surface for the samples with equal to or less than 3.6 mol% WO 3 and contributed to an increase of the surface acidity. Crystalline WO 3 was formed for samples with >3.6 mol% WO 3 . Formation of crystalline WO 3 is attributed to the enhanced rate of condensation of W species with increasing loading of tungsten. Variation of l (defined as the ratio of the actual oxygen-to-fuel ratio of the reactants to the stoichiometric oxygen-to-fuel ratio) influences the residence time of the particles in the high temperature flame and affects the type of surface species and thereby the resultant acidity. The photocatalytic activity of the composite particles was tested for the degradation of methylene blue (MB) and was compared with that of commercial Degussa P25-TiO 2 . The improved photocatalytic activity of the composite particles is attributed to the increased surface acidity and better charge separation due to the coupling of WO x species and TiO 2 within the composite nanoparticles. #
Synthesis, Surface Acidity and Photocatalytic Activity of WO3/TiO2 Nanocomposites – An Overview
Titania has been studied to be one of the best photocatalysts for the decomposition of many organic pollutants present in aqueous medium. Because of the wide band gap energy of TiO 2 (3.2 eV) it can be activated only under UV light region which is present 4 % in the solar light spectrum. The photocatalytic activity of TiO 2 was enhanced by means of several methods. TiO 2 coupled with other semiconductor has gained additional importance, owing to improving the efficient charge separation by trapping the photogenerated electrons. WO 3 is a better semiconductor having relatively lower band gap energy (2.8 eV) and absorb broad solar light spectrum. The formation of WO x monolayer on TiO 2 notably increases the surface acidity of TiO 2 . This increasing the surface acidity of WO 3 /TiO 2 photocatalyst facilitates the adsorption of the more hydroxyl group in addition to more organic reactants on its surface which obviously facilitate the enhancement of photocatalytic activity. In this review, the synthesis methods and photocatalytic activity of some selected and unique results related to WO 3 /TiO 2 photocatalyst were discussed. The efficient charge separation, increased absorption of the reactants by increasing the surface acidity and high aspect ratio structures of WO 3 /TiO 2 are also reviewed.
Applied Water Science, 2023
In this work, crash precipitation technique was employed to synthesize a visible light-responsive tungsten trioxide (WO 3) photocatalyst using ammonium paratungstate as tungsten precursor. The spray-dried (120 °C) and calcined (600 °C) WO 3 powder was characterized by analyzing methods of XRD, PSD, BET and BJH, Raman, FESEM/EDX, FTIR, UV-vis DRS and XPS spectroscopy. X-ray diffraction (XRD) and Raman studies confirm the well crystalline monoclinic crystal structure. Scanning electron microscopy (SEM) images showed micron-sized spherical bulks of WO 3 particles with needle-like morphology. A normal distribution with a d 50 (median diameter) value of 6.0 μm was observed with particle size analysis. Much enhanced BET surface area of 102 g/m 2 with wide pore size 1.8 nm is measured compared to commercially available WO 3 that results in increased pollutants surface adsorption. Fourier transform infrared spectroscopy (FTIR) study demonstrated that the calcined sample surface is enriched with bonded hydroxyl groups, beneficial for powder particles activity. Photocatalyst band gap was calculated by considering the absorbance measurements recorded on UV-vis diffuse reflectance spectroscopy (DRS). The energy value of 2.6 eV was calculated which lies in the visible light region while X-ray photoelectron spectroscopy (XPS) analysis showed 6 + oxidation state for tungsten. Bulk WO 3 sphere photocatalytic activity was evaluated through the exertion of synthetic textile methylene blue (MB) dye and sulfamethoxazole (SMX) pharmaceutical antibiotic. The obtained activity results showed 85% and 100% degradation for MB and SMX under 100 min visible light irradiation. We expect that our work may provide a new sample for energy production (H 2) through water photolysis, gas sensing and soft matter research.
Langmuir, 2001
Tungstated titania catalysts (WOx/TiO2) were prepared by wet impregnation of hydrous titanium oxide hydroxide. The influences on the catalyst structure of tungsten loading (in the range of 0-30 wt % WO3 supported on TiO2), calcination temperature (varied from 473 to 973 K), and the form of the applied tungstate precursor (ammonium metatungstate or ammonium monotungstate) were investigated by surface area measurements, X-ray diffraction, thermal analysis, temperature-programmed reduction, vibrational and UV/vis spectroscopy, and X-ray absorption spectroscopy. The data show that tungsten loadings giving higher than monolayer coverage of the TiO2 and the application of a high-surface-area titania precursor lead to new structural properties of the surface tungstate phase. A tungstate overlayer is formed that is stable at loadings up to ca. two monolayers (20 wt % WO3/TiO2) at a calcination temperature of 923 K. Two tungstate species are characterized by two WdO bands in the vibrational spectra. One tungstate species shows a strong dependence of its domain size and degree of condensation on calcination temperature and tungsten loading, but the other does not. The first is attributed to accessible outer segments of a three-dimensional tungstate structure and the latter to the interface providing the linkage to the TiO2 support. A three-dimensional structure is formed even at low tungsten coverages. This tungstate overlayer retards the sintering of the TiO2 support and its phase transformation from anatase to rutile. With increasing tungsten loading, the surface area increases and the TiO2 particle sizes and pore diameters decrease. When the tungsten loading exceeds 20 wt % WO3 and the calcination temperature exceeds 923 K, WO3 is formed. These results are supposed to help to explain the properties of these materials including acidity, reactivity in reduction, and isotope exchange.