Papers by Keyword: WO₃

Abstract: This study developed WO₃/WS₂ composites loaded with noble metals to degrade methyl orange under UV light. Pure WO₃/WS₂ and variations loaded with Au, Ag, Pt, Ru, and Rh were among the photocatalysts. To examine the materials' structural, morphological, and optical characteristics, X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy were used. The highest photocatalytic activity was observed with Au@WO₃/WS₂, degrading MO by 98.59 %. The synergistic interactions between Au nanoparticles and the WO₃/WS₂ heterostructure improved charge separation and light absorption, indicating the composites' potential for effective UV-active photocatalysts for environmental remediation.

Abstract: Present work illustrates synthesis of Cr doped WO₃ nanostructures (NS) (2 wt. %, 4 wt. % and 6 wt. %) by co precipitation method using surfactants and reported enhanced impedance, capacitance-voltage and current-voltage (I-V) characteristics. NS were characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible (UV-Vis) spectroscopy, pelletized samples performed I-V, C-V and impedance measurements. Impedance results reveal that the pelletized samples of highest doped Cr showed remarkable increase in admittance with respect to the biased voltage. I-V characteristics of highest doped Cr exhibited enhanced surface conductivity as compared with applied current. The output power considerably increases for the 6 wt. % of Cr doped WO₃ and doping percentage of Cr increases surface conductivity, power output, admittance considerably enhances in the material matrix. This work demonstrated that Cr doped WO₃ has more sensitivity towards I-V, C-V and impedance value considerably varies with the applied bias voltage. The limitation is not certain in case of doped nanomaterials of Cr-WO₃, since these materials possesses nonlinear properties and can find applications in the diversified filed of nano electronics. The authors reported work can be a key guide for the upcoming researchers in the area of biomedical devices, nanoelectronics, sensors, wherein Cr-WO₃ NS finds applications because of its enhanced I-V, C-V, Impedance characteristics. The work has been carried out to understand the electrical and electronic properties of doped nanomaterials in the original work place and analysis has been carried out at various institutions where the provisions for the experimentation is being made.

Abstract: Tungsten trioxide (WO₃) nanostructures were synthesized by a hydrothermal method, and the influence of essential hydrothermal conditions, temperature and time, on their crystal structure, morphology and visible-light driven photocatalysis was studied. The hydrothermal temperature was varied from 120 °C to 200 °C, and the hydrothermal time changed from 12 h to 32 h. The crystal structure, morphology and photocatalytic performance of WO₃ nanostructures were characterized by XRD, SEM and UV-Vis. The crystal structure of WO₃ nanostructure was triclinic phase and their morphology was mainly one dimensional nanorods. Methylene blue was used as the target to evaluate their photocatalytic performance under visible light (λ>420 nm). The photocatalytic results suggest the suitable hydrothermal conditions to synthesize WO₃ nanostructures for the wastewater treatment application.

Abstract: Conventionally, palm oil mill effluent (POME) was treated using open ponding system, which nevertheless long retention times and large treatment areas were required. In this report, heterogeneous photocatalysis was used to degrade the POME and simultaneously assessed the biogas formation. Characterization of the chemically prepared hierarchical porous ZnO microspheres showed that wurtzite was the predominant crystalline phase with a band gap energy of 3.22 eV. Moreover, the as-prepared ZnO were assembled by large numbers of interleaving nanosheets and formed an open porous structure. Under UV irradiation, the as-prepared ZnO demonstrated photocatalytic property on POME degradation. The WO₃ and Nb₂O₅ decorated ZnO photocatalysts (WO₃/ZnO and Nb₂O₅/ZnO) with improved photocatalytic performances were also prepared using a simple and rapid way. Significantly, in the presence of WO₃/ZnO and Nb₂O₅/ZnO composites, the degradation of POME achieved 68.3% and 91.7%, respectively after 240 min irradiation. Interestingly, the assessment of the biogas formation showed that the photocatalytic reactions over Nb₂O₅/ZnO and WO₃/ZnO composites generated higher amount of biogas products (CH₄ + CO₂) compared to that of ZnO. The photocatalytic enhancement was attributed to the high separation efficiency of photogenerated electron–hole pairs based on the formation of heterojunction structures between the WO₃/Nb₂O₅ and ZnO. The observed findings also revealed that the photocatalytic technology using hierarchical WO₃/ZnO and Nb₂O₅/ZnO composites had the potential to efficiently treat wastewater.

Abstract: WO₃ nanostructure with nanocube morphology was synthesized through acidification of Na₂WO₄·2H₂O, which were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the result of the present work implied that the sensor fabricated by nanocube WO₃ could detect the level of 330 ppb H₂S, which is much lower than the threshold limit value of 10 ppm. Compared with other results, the nanocube WO₃ sensor shows higher sensitivity, excellent selectivity and faster response/recovery to H₂S. Especially, the best operating temperature of this nanocube WO₃ for H₂S detection is 100 °C.

Abstract: In order to synthesize cordierite ceramics with low thermal expansion coefficient and good properties, in our work, the cordierite ceramics were prepared by using talc, natural containing zirconium kyanite, common kyanite and industrial Al₂O₃ as raw materials, introducing the right amount of WO₃ (introducing tungsten acid) as catalyst. The effects of the introduced WO₃ on the phase composition, sintering characters, microstructure and thermal expansion coefficient of the cordierite ceramics were investigated. The results show that the introduction of WO₃ can eliminate the intermediate phase magnesia-alumina spinel and promote the formation of cordierite; the as-prepared cordierite ceramics synthesized by using natural containing zirconium kyanite as raw materials have high densification degree and low thermal expansion coefficient (1.53×10^-6/°C, Rt~1000 °C).

Abstract: Effective ways to treat textile industrial effluents have been studied in attempt to find alternatives to reduce the imminent risk of water resources contamination. The heterogeneous photocatalysis stands out in this scenario working in the organic waste mineralization, such as dyes. The objectives of this study were to investigate the obtaining of fine powders of the WO₃:TiO₂ (the investigated proportions in this work were 0: 100; 30:70; 50:50; 70:30; 100:0) using the high energy milling technique and to evaluate the photocatalytic efficiency of the Rhodamine B dye in this system. The oxides precursors were characterized by X-ray diffraction, BET and Helium pycnometry. After dry milling for 4 hours, the obtained powders were characterized by X-ray diffraction and tested to the photocatalysis in UV-C. The results indicate that the milling process has a direct influence on the photocatalytic properties of the investigated systems, and that the greater presence of titania in the mixture leads to a greater catalytic effect.

Abstract: WO₃ particles with different grain sizes were prepared by a thermal evaporation method. The composition, morphology, and optical properties of the samples were analyzed by powder X-ray diffraction, scanning electron microscopy, and UV–vis absorption and photoluminescence spectroscopy. Their photocatalytic properties were evaluated by decomposing methylene blue in aqueous phase. It was found that the smaller the grain size of the prepared WO₃ particles, the better the degradation effect on methylene blue.

Abstract: Nanoscale material world attracted researchers because of their outstanding properties and prospective novel applications. Tungsten trioxide semiconductor is one of the fundamental functional materials due to its versatile application as gas sensors, solar cells, and smart windows. Confined growth of the metal oxide nanostructures can tune the electrical and optical properties for modern device application. The management of morphology is a challenge to investigate the ultimate performance. In this paper, self-assembled growth of four different tungsten trioxide nanostructures were carried using a different structure directing agents through either co-precipitation or hydrothermal techniques. The monoclinic spherical and rod-like WO₃ nanostructures were obtained by acid precipitation method. WO₃ nanocuboids and nanofibers were synthesized hydrothermally using HBF₄ and NaCl as structure directing reagents to attain monoclinic and hexagonal crystal phases, respectively. Analytical techniques like XRD, TEM, and FESEM imaging methods were used to confirm the phase and morphology. All the nanopowders were calculated to have similar band gap energy at visible wavelength. A simple dip coated WO₃/ITO fabricated electrode was used as a reference electrode to carry out the electrochemical measurements for all nanopowders. The evaluated properties suggested the plausible use of WO₃ nanofibers for high efficient electrochromic device.

Abstract: Porous tungsten oxide (WO₃) nanofibers were synthesized by electrospinning aqueous solutions of polyvinylpyrrolidone (PVP) and ammonium metatungstate (AMT). The as-spun fibers and their annealing were studied by scanning electron microscope (SEM). SEM results showed that the WO₃ fibers have a large amount of pores with diameters ranging from 50 nm to 100 nm, and pure monoclinic WO₃ nanoscaled fibers formed between 500 and 600 °C. When a higher temperature (700 °C) was used, the tungsten oxide nanofibers totally disintegrated. When heated at 600 °C, the fibers broken into nanorods by the mechanical pressure. However, when the annealing treatment was low (500 °C), the fiber-like crystalline structure that can be seen. When the optimal temperature was used, the structure of the obtained WO₃ nanofibers with novel morphology and crystallinity were captured.