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Published: 10 December 2022
Last updated: 29 January 2023

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1

Lin, Hong-Ming, Chiun-Yen Tung, Chi-Ming Hsu, and Pee-Yew Lee. "Catalytic properties of nanocrystalline WO3−x, Pt/WO3−x, and Pd/WO3−x particles." Journal of Materials Research 10, no. 5 (May 1995): 1115–19. http://dx.doi.org/10.1557/jmr.1995.1115.

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The gas-condensation technique is used to produce the nanocrystalline (NC) WO3−x, Pt/WO3−x, and Pd/WO3−x powders under different atmosphere and pressure. HRTEM images show that a coherently bonded interface exists between Pt or Pd and WO3−x. The nanocrystal WO3−x, Pt/WO3−x, and Pd/WO3−x grow into a needle shape with a plate inside when these as-evaporated powders are compacted and sintered at 900 °C for 2 h. The plate grows preferentially in {220} plane along the 〈0011〉 direction. However, the mean particle size of nanophase Pt and Pd increases only from <10 nm to 30 nm and 50 nm, respectively. The results of CO oxidation show that nanophase Pt/WO3−x powders have better catalytic effects on converting CO to CO2 than nanophase WO3−x and Pd/WO3−x powders.
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2

Bashirom, Nurulhuda, and Qiao Ling Lee. "Synthesis of Visible-Light Active Monoclinic WO3 by Thermal Oxidation of Tungsten Powder for Photoreduction of Cr(VI)." Materials Science Forum 1010 (September 2020): 405–10. http://dx.doi.org/10.4028/www.scientific.net/msf.1010.405.

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In this paper, visible-light-active monoclinic WO3 powders were synthesized by thermal oxidation of W powders at 200 – 1000 °C in air atmosphere. Morphology and crystal structure of annealed W powders were characterized by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively. Based on SEM and XRD results, a spherical orthorhombic-W3O8 obtained at 200 °C was transformed into a dendritic monoclinic WO2 + tetragonal WO3 + monoclinic WO3 structures at 400 °C accompanied by a color transition from grey into green. At 600 °C, yellow monoclinic WO3 + monoclinic WO2.96 powder was produced that ascribed to oxygen vacancies. Photocatalytic activity of annealed W powders demonstrated 70.7% Cr (VI) removal after 150 min on sample annealed at 1000 °C. This ascribed to high photoactivity of monoclinic WO3. Nevertheless, the dendritic monoclinic WO2 + tetragonal WO3 + monoclinic WO3 obtained at 400 °C exhibited the lowest Cr (VI) photoreduction i.e. 45.2% implies less photoactive monoclinic WO2 and sluggish electron transport at oxide-oxide interfaces.
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3

Franco, Douglas Faza, Hassen Fares, Antônio Eduardo De Souza, Silvia Helena Santagneli, and Marcelo Nalin. "Glass formation in the Sb2O3-SbPO4-WO3 system." Eclética Química Journal 42, no. 1 (December 30, 2017): 51. http://dx.doi.org/10.26850/1678-4618eqj.v42.1.2017.p51-59.

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Glasses in the ternary system (Sb2O3)(0.6-x)(SbPO4)(0.4)(WO3)(x), with composition 0.1 £ x £ 0.5 were studied. The structural changes due to the replacement of Sb2O3 by WO3 have been investigated. It was found that the incorporation of WO3 enhances the thermal stability of the glasses against devitrification when compared to the binary Sb2O3(0.6) - SbPO4(0.4) composition. The connectivity of the network increases with WO3 content which is consistent with the high values of the glass transition temperature. Raman studies suggest that WO3 incorporation breaks the primary network, constituted by antimony oxide, while a second network containing WO6 octahedral units is built up. Thermal and structural properties were evaluated by differential scanning calorimetry, infrared and Raman spectroscopies, 31P Magic Angle Spinning NMR and X-ray absorption near edge structure (XANES) at L1 and L3 edges of Sb and L1 edge of W atoms.
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4

Salleh, Fairous, Tengku Shafazila Tengku Saharuddin, Alinda Samsuri, Rizafizah Othaman, Mohammad Wahab Mohammad Hisham, and Mohd Ambar Yarmo. "Influence of Cerium Additive on the Reduction Behaviour of Tungsten Oxide under Carbon Monoxide Atmosphere." Materials Science Forum 888 (March 2017): 389–93. http://dx.doi.org/10.4028/www.scientific.net/msf.888.389.

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The reduction of pure WO3 and Ce/WO3 has been studied by using temperature programmed reduction (TPR), X-ray diffraction (XRD), and FESEM analysis. The reduction behavior were examined by non-isothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR results shows that reduction peak of Ce/WO3 were shifts to lower temperature as compared with to the pure WO3. In addition, TPR results indicate that addition with ceria give better reducibility compared to pure WO3. Based on the characterization of the reduction products after hold 45 min using XRD, pure WO3 were completely converted to WO2 and W metal phases. While, after addition of Ce to the WO3, the reduction was enhanced to W phases and some suboxide W5O14 and W3O5 with no WO2 phase remained and carbide observed. This is associated to the formation of alloy complex Ce2WO6 which gave remarkable effect to the reduction.
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5

Albanese, Elisa, Cristiana Di Valentin, and Gianfranco Pacchioni. "H2O Adsorption on WO3 and WO3–x (001) Surfaces." ACS Applied Materials & Interfaces 9, no. 27 (June 28, 2017): 23212–21. http://dx.doi.org/10.1021/acsami.7b06139.

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6

Wang, Biben, Xiaoxia Zhong, Haiyan Xu, Yongcai Zhang, Uros Cvelbar, and Kostya (Ken) Ostrikov. "Structure and Photoluminescence of WO3-x Aggregates Tuned by Surfactants." Micromachines 13, no. 12 (November 25, 2022): 2075. http://dx.doi.org/10.3390/mi13122075.

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The optoelectronic properties of transition metal oxide semiconductors depend on their oxygen vacancies, nanostructures and aggregation states. Here, we report the synthesis and photoluminescence (PL) properties of substoichiometric tungsten oxide (WO3-x) aggregates with the nanorods, nanoflakes, submicro-spherical-like, submicro-spherical and micro-spherical structures in the acetic acid solution without and with the special surfactants (butyric or oleic acids). Based on theory on the osmotic potential of polymers, we demonstrate the structural change of the WO3-x aggregates, which is related to the change of steric repulsion caused by the surfactant layers, adsorption and deformation of the surfactant molecules on the WO3-x nanocrystals. The WO3-x aggregates generate multi-color light, including ultraviolet, blue, green, red and near-infrared light caused by the inter-band transition and defect level-specific transition as well as the relaxation of polarons. Compared to the nanorod and nanoflake WO3-x aggregates, the PL quenching of the submicro-spherical-like, submicro-spherical and micro-spherical WO3-x aggregates is associated with the coupling between the WO3-x nanoparticles and the trapping centers arising from the surfactant molecules adsorbed on the WO3-x nanoparticles.
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7

Lee, Seong, Joon Woong Noh, Eun Pyo Kim, and Moon Hee Hong. "Reduction Behavior of W and Cu Oxides Powder Mixture." Solid State Phenomena 135 (February 2008): 143–49. http://dx.doi.org/10.4028/www.scientific.net/ssp.135.143.

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The reduction behavior of WO3 and CuO powder mixture has been studied by using thermo-gravimetric(TG), X-ray diffraction, and scanning electron microscopic analyses. The powder mixture was manufactured by ball-milling. It was found that W coated W-Cu composite powders were formed when reducing the powder mixture under hydrogen atmosphere. The following reduction steps are suggested as a mechanism for the formation of W coated W-Cu composite powders: with increasing temperature, Cu is initially reduced from CuO and the reduction reactions of WO3 to WO2 via WO2.9 and WO2.72 are followed. The gas phase WO2(OH)2 is formed by the reaction of the WO2 and water vapor, and then WO2(OH)2 diffuses toward Cu surface and deposits on it as W by reducing reaction with environmental hydrogen gas. The formation mechanism of W coated W-Cu composite powders involving the gas phase transportation reaction has been confirmed by the model experiment conducted by using Cu plate and WO3 powder.
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8

Liu, Yanhong, Chunxia Wang, Zhongyue Li, Yusheng Wang, Wenqi Lu, and Huolin Huang. "Effects of W/ WO3-x junction on synaptic characteristics of W/WO3-x/ITO memristor." Physica E: Low-dimensional Systems and Nanostructures 127 (March 2021): 114515. http://dx.doi.org/10.1016/j.physe.2020.114515.

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9

Avellaneda, C. "Photochromic properties of WO3 and WO3:X (X=Ti, Nb, Ta and Zr) thin films." Solid State Ionics 165, no. 1-4 (December 2003): 117–21. http://dx.doi.org/10.1016/j.ssi.2003.08.023.

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10

Deng, Henghua, Dongfang Yang, Bo Chen, and Chii-Wann Lin. "Simulation of surface plasmon resonance of Au–WO3−x and Ag–WO3−x nanocomposite films." Sensors and Actuators B: Chemical 134, no. 2 (September 2008): 502–9. http://dx.doi.org/10.1016/j.snb.2008.05.032.

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11

Salleh, Fairous, Tengku Shafazila Tengku Saharuddin, Alinda Samsuri, Rizafizah Othaman, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Reduction Behaviour of WO3 to W under Carbon Monoxide Atmosphere." Materials Science Forum 840 (January 2016): 305–8. http://dx.doi.org/10.4028/www.scientific.net/msf.840.305.

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The reduction behaviour of tungsten oxide has been studied by using temperature programmed reduction (TPR) and X-ray diffraction (XRD). The reduction behavior were examine by nonisothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min time under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR signal clearly shows one peak attributed to formation of suboxide W18O49 (more) and WO2 (less) observed at 80 min. The reduction product was investigated by varying the holding reaction time. Based on the characterization of the reduction products by using XRD, it was found that, nonisothermal reduction of WO3 at temperature 900 oC partially converted to some W18O49 and WO2 phases. However, after increased the reaction holding time for 45 min, WO3 phases disappeared and converted to WO2 and W metal phases. It is obviously shows that by hold the reduction time could improve the reducibility of the sample oxide. Furthermore, it is suggested that reduction by using CO as reducing agent follows the consecutives steps WO3 → WO2.92 → W18O49 → WO2 → W.
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12

Shen, Yan Fang, Tian Ying Xiong, Jian Ku Shang, and Ke Yang. "Nano-Sized Nitrogen-Doped Ti-W Mixed Oxides: Preparation and Enhanced Photocatalytic Activities under Visible Light Irradiation." Materials Science Forum 569 (January 2008): 1–4. http://dx.doi.org/10.4028/www.scientific.net/msf.569.1.

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Nano-sized nitrogen-doped Ti-W mixed oxides (N-TiO2-x%WO3) were prepared by soft chemical method, and their intrinsic characteristics were investigated using XRD, TEM, N2 adsorption and desorption isotherms, UV-Vis diffuse reflectance spectra and XPS. Experiments on photodegradation of Methylene Blue (MB) under visible light irradiation were carried out to evaluate the photocatalytic abilities of N-TiO2-x%WO3. Chemical Oxygen Demand (COD) analysis was also performed to evaluate the mineralization abilities of N-TiO2-x%WO3. It is shown that the N-TiO2-x%WO3 exhibited higher COD removing rates compared with Degussa P25. The color bleaching rates of N-TiO2-x%WO3 were equal to that of Degussa P25. The enhanced photocatalytic activities were probably related to the strong absorption abilities of the N-TiO2-x%WO3.
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13

SRINIVASA RAO, LINGANABOINA, and TUMU VENKATAPPA RAO. "DSC, ESR AND IR SPECTRAL STUDIES ON Li2O–WO3–B2O3 GLASS SYSTEM DOPED WITH VANADIUM IONS." Functional Materials Letters 02, no. 03 (September 2009): 127–30. http://dx.doi.org/10.1142/s1793604709000661.

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With in glass forming region of Li2O–WO3–B2O3 glass system, a particular composition 40Li2O–5WO3–(55 –x) B2O3 : x V2O5 (with x ranging from 0.2 to 0.8, all are in mol.%) is chosen. The DSC traces are obtained to identify the glass transition temperature ( Tg ) and the glass forming ability of all the glass samples. The ESR and IR spectra portray the local structure of the glass system and valance states of the vanadium ions in the glass matrix. As the content of V2O5 increases up to 0.6 mol.% in the glass system, a gradual conversion of vanadium ions from V5+ state to V4+ state is observed, causing the depolymerization in the glass matrix by the transformation of several glass forming units BO4 → BO3 and WO4 → WO6 .
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14

Szkoda, Mariusz, Zuzanna Zarach, Konrad Trzciński, Grzegorz Trykowski, and Andrzej P. Nowak. "An Easy and Ecological Method of Obtaining Hydrated and Non-Crystalline WO3−x for Application in Supercapacitors." Materials 13, no. 8 (April 19, 2020): 1925. http://dx.doi.org/10.3390/ma13081925.

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In this work, we report the synthesis of hydrated and non-crystalline WO3 flakes (WO3−x) via an environmentally friendly and facile water-based strategy. This method is described, in the literature, as exfoliation, however, based on the results obtained, we cannot say unequivocally that we have obtained an exfoliated material. Nevertheless, the proposed modification procedure clearly affects the morphology of WO3 and leads to loss of crystallinity of the material. TEM techniques confirmed that the process leads to the formation of WO3 flakes of a few nanometers in thickness. X-ray diffractograms affirmed the poor crystallinity of the flakes, while spectroscopic methods showed that the materials after exfoliation were abundant with the surface groups. The thin film of hydrated and non-crystalline WO3 exhibits a seven times higher specific capacitance (Cs) in an aqueous electrolyte than bulk WO3 and shows an outstanding long-term cycling stability with a capacitance retention of 92% after 1000 chronopotentiometric cycles in the three-electrode system. In the two-electrode system, hydrated WO3−x shows a Cs of 122 F g−1 at a current density of 0.5 A g−1. The developed supercapacitor shows an energy density of 60 Whkg−1 and power density of 803 Wkg−1 with a decrease of 16% in Csp after 10,000 cycles. On the other hand, WO3−x is characterized by inferior properties as an anode material in lithium-ion batteries compared to bulk WO3. Lithium ions intercalate into a WO3 crystal framework and occupy trigonal cavity sites during the electrochemical polarization. If there is no regular layer structure, as in the case of the hydrated and non-crystalline WO3, the insertion of lithium ions between WO3 layers is not possible. Thus, in the case of a non-aqueous electrolyte, the specific capacity of the hydrated and non-crystalline WO3 electrode material is much lower in comparison with the specific capacity of the bulk WO3-based anode material.
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15

Abdullah, S. F., S. Radiman, M. A. Abdul Hamid, and N. B, Ibrahim. "Studies on the phase transitions and properties of tungsten (VI) oxide nanoparticles by X-Ray diffraction (XRD) and thermal analysis." ASEAN Journal on Science and Technology for Development 26, no. 1 (November 26, 2017): 13–20. http://dx.doi.org/10.29037/ajstd.300.

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Tungsten (VI) oxide, WO3 nanoparticles were synthesized by colloidal gas aphrons (CGAs) technique. The resultant WO3 nanoparticles were characterized by thermogravimetric-differential thermal analysis (TG-DTA) and X-Ray diffraction (XRD) measurements in order to determine the phase transitions, the crystallinity and the size of the WO3 nanoparticles. As a comparison, transmission electron microscope (TEM) was used to investigate the size of the WO3 nanoparticles. The result from XRD and DTA show that the formation of polymorphs WO3 nanoparticles have the following sequence: orthorhombic (bWO3) ® monoclinic (g-WO3) ® triclinic (d-WO3) ® monoclinic (e-WO3) with respect to the calcination temperature of 400, 500, 600 and 700°C. No diffraction peaks were found in the X-Ray diffraction measurements for the sample heat treated at 300°C (as-prepared), suggesting that an amorphous structure was obtained at this temperature whereas the crystallinity had been obtained by the other samples of the WO3 nanoparticles at the calcination temperatures of 400, 500, 600 and 700°C. It is also found that the X-Ray diffraction measurements produced an average diameter of (30 ± 5), (50 ± 5), (150 ± 10) and (200 ± 10) nm at calcination temperatures of 400, 500, 600 and 700°C respectively by using Debye-Scherrer formula. The TG curve revealed that the WO3 nanoparticles is purely anhydrous since the weight loss is insignificant (0.3 – 1.4) % from 30 until 600°C for the WO3 nanoparticles calcined at 400°C. Finally, the composition and the purity of the WO3 nanoparticles have been examined by X-Ray photoelectron spectroscopy (XPS). The results indicate no significant changes to the composition and the purity of the WO3 nanoparticles produced due to the temperature variations.
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16

Hanioka, Chihiro, Kaichi Omura, and Hiroshi Irie. "Anomalous photo-thermoelectric effects of platinum-photodeposited tungsten trioxide after gaschromic reaction." Journal of Applied Physics 131, no. 18 (May 14, 2022): 185102. http://dx.doi.org/10.1063/5.0079246.

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We attempted to deposit platinum (Pt) onto a tungsten trioxide (WO3) thin film by the photoreduction of Pt4+ (Pt–WO3). Pt on WO3 was oxidized (PtO x) by calcining Pt–WO3 in air to form PtO x–WO3. An n-type anomalous photo-thermoelectric (photo-TE) effect was confirmed for Pt–H yWO3− x, a protonated WO3, after the gaschromic (GC) reaction of Pt–WO3. That is, both the electrical conductivity ( σphoto) and the absolute value of the Seebeck coefficient ( Sphoto) increased under visible-light irradiation. After stopping the irradiation, both values decreased ( σ and S). In contrast, an n-type normal photo-TE effect was observed for PtO x–H yWO3− x after the GC reaction of PtO x–WO3, in which σphoto and the absolute value of Sphoto increased and decreased, respectively, under visible-light irradiation, and vice versa after stopping the irradiation. These findings indicate that Pt was responsible for the generation of the anomalous photo-TE effect, probably due to the electron accumulation capability of Pt, to which electrons were transferred from the conduction band of H yWO3− x. In contrast, electrons could not energetically transfer from H yWO3− x to PtO2, which was included in PtO x particles at the surface. Therefore, PtO x was not responsible for the anomalous photo-TE effect, and PtO x–H yWO3− x behaved like bare H yWO3− x, indicating its normal photo-TE effect.
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17

Hepel, Maria, and Haley Redmond. "Large cation model of dissociative reduction of electrochromic WO3−x films." Open Chemistry 7, no. 2 (June 1, 2009): 234–45. http://dx.doi.org/10.2478/s11532-009-0009-z.

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AbstractStudies of dissociative reduction processes of electrochromic WO3−x films were conducted to: (i) evaluate their utility for electroetching and (ii) determine their fundamental mechanistic features to reduce or eliminate their occurrence in normal optical switching and modulation operation of WO3−x films. We have found that while the small intercalating cations stabilize WO3−x structure, the large nonintercalating surfactant cations (Et4N+, CtMe3N+) contribute to the dissociative reduction. While these cations do not affect WO3−x structure of anodically protected films (E &gt; 0.2 V), they cause surface lattice polarization on electron injection to the conduction band of WO3−x at lower electrode potentials, in the absence of intercalating cations. We have found that this process is limited to the surface and no structural damage occurs to the underlying film. The mechanistic aspects of the process have been discussed on the basis of experimental voltammetric and electrochemical quartz crystal nanogravimetric (EQCN) measurements and ab initio quantum mechanical calculations.
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18

Liao, Chia-Ching, Fu-Rong Chen, and Ji-Jung Kai. "WO3−x nanowires based electrochromic devices." Solar Energy Materials and Solar Cells 90, no. 7-8 (May 2006): 1147–55. http://dx.doi.org/10.1016/j.solmat.2005.07.009.

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19

Locherer, K. R., J. Chrosch, and E. K. H. Salje. "Diffuse X-ray scattering in WO3." Phase Transitions 67, no. 1 (October 1998): 51–63. http://dx.doi.org/10.1080/01411599808219188.

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20

Olejníček, J., A. Hrubantová, L. Volfová, M. Dvořáková, M. Kohout, D. Tvarog, O. Gedeon, H. Wulff, R. Hippler, and Z. Hubička. "WO3 and WO3-x thin films prepared by DC hollow cathode discharge." Vacuum 195 (January 2022): 110679. http://dx.doi.org/10.1016/j.vacuum.2021.110679.

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21

Chen, Shihao, Yang Xiao, Wei Xie, Yinhai Wang, Zhengfa Hu, Wei Zhang, and Hui Zhao. "Facile Strategy for Synthesizing Non-Stoichiometric Monoclinic Structured Tungsten Trioxide (WO3−x) with Plasma Resonance Absorption and Enhanced Photocatalytic Activity." Nanomaterials 8, no. 7 (July 21, 2018): 553. http://dx.doi.org/10.3390/nano8070553.

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Oxygen vacancy defects play an important role in improving the light-capturing and photocatalytic activity of tungsten trioxide (WO3). However, the hydrogen treatment method that is commonly used to introduce oxygen vacancies is expensive and dangerous. Therefore, the introduction and control of oxygen vacancy defects in WO3 remains a challenge. Here, we demonstrated that oxygen vacancies could be successfully introduced into WO3−x while using a facile method through low temperature annealing in alcohol. The obtained WO3−x samples with optimal oxygen vacancies showed strong absorption of light, extending from the ultraviolet to the visible and near-infrared regions, and exhibits strong plasmon resonance from 400–1200 nm peaking at approximately 800 nm. When compared to pristine WO3, the photocatalytic activity of WO3−x was greatly improved in the ultraviolet and visible regions. This study provides a simple and efficient method to generate oxygen vacancies in WO3 for photocatalysis, which may be applied in the photoelectrochemical, electrochromic, and photochromic fields. Because oxygen vacancy is a common characteristic of metal oxides, the findings that are presented herein may be extended to other metal oxides.
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22

Shen, Zhenguang, Zengying Zhao, Jian Wen, Jingwen Qian, Zhijian Peng, and Xiuli Fu. "Role of Oxygen Vacancies in the Electrical Properties of WO3−x Nano/Microrods with Identical Morphology." Journal of Nanomaterials 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/7802589.

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Tungsten oxide (WO3−x) crystalline nano/microrods with identical morphology but different contents of oxygen vacancies were prepared by thermally evaporating fixed amount of WO3 powder in reductive atmosphere from different amounts of S power at 1150°C in a vacuum tube furnace, in which both sources were loaded in separate ceramic boat. With increasing amount of S powder, a series of tungsten oxides, WO3, WO2.90, W19O55 (WO2.89), and W18O49 (WO2.72), could be obtained. And devices were fabricated by screen-printing the obtained WO3−x crystals on ceramic substrates with Ag-Pd interdigital electrodes. With increasing content of oxygen vacancies, the devices fabricated with WO3−x crystals present a negative to positive resistance response to relative humidity. Under dry atmosphere, for the devices with increasing x, the strong response to light changed from short to long wavelength; under light irradiation, the conducting ability of the devices was enhanced, due to the more efficient separation and transportation of the photogenerated carriers; and under simulated solar irradiation, the photocurrent intensity of the W18O49 device was roughly 8 times, about 500 times, and even 1000 times larger than that of the W19O55, WO2.90, and WO3 one, respectively. With the versatile optoelectrochemical properties, the obtained WO3−x crystals have the great potential to prepare various humidity sensors and optoelectrical devices.
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23

Salje, Ekhard K. H. "Polaronic States and Superconductivity in WO3-x." Condensed Matter 5, no. 2 (May 1, 2020): 32. http://dx.doi.org/10.3390/condmat5020032.

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Superconducting domain boundaries were found in WO3-x and doped WO3. The charge carriers in WO3-type materials were identified by Schirmer and Salje as bipolarons. Several previous attempts to determine the electronic properties of polarons in WO3 failed until Bousque et al. (2020) reported a full first principle calculation of free polarons in WO3. They confirmed the model of Schirmer and Salje that each single polaron is centred around one tungsten position with surplus charges smeared over the adjacent eight tungsten positions. Small additional charges are distributed further apart. Further calculations to clarify the coupling mechanism between polaron to form bipolarons are not yet available. These calculations would help to identify the carrier distribution in Magneli clusters, which were shown recently to contain high carrier concentrations and may indicate totally localized superconductivity in non-percolating clusters.
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24

Roussel, P., O. Pérez, and Ph Labbé. "Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors." Acta Crystallographica Section B Structural Science 57, no. 5 (September 29, 2001): 603–32. http://dx.doi.org/10.1107/s0108768101009685.

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Phosphate tungsten bronzes have been shown to be conductors of low dimensionality. A review of the crystallographic and structural properties of this huge series of compounds is given here, corresponding to the present knowledge of the different X-ray studies and electron microscopy investigations. Three main families are described, monophosphate tungsten bronzes, Ax (PO2)4(WO3)2m , either with pentagonal tunnels (MPTBp) or with hexagonal tunnels (MPTBh), and diphosphate tungsten bronzes, Ax (P2O4)2(WO3)2m , mainly with hexagonal tunnels (DPTBh). The general aspect of these crystal structures may be described as a building of polyhedra sharing oxygen corners made of regular stacking of WO3-type slabs with a thickness function of m, joined by slices of tetrahedral PO4 phosphate or P2O7 diphosphate groups. The relations of the different slabs with respect to the basic perovskite structure are mentioned. The structural description is focused on the tilt phenomenon of the WO6 octahedra inside a slab of WO3-type. In this respect, a comparison with the different phases of the WO3 crystal structures is established. The various modes of tilting and the different possible connections between two adjacent WO3-type slabs involve a great variety of structures with different symmetries, as well as the existence of numerous twins in MPTBp's. Several phase transitions, with the appearance of diffuse scattering and modulation phenomena, were analysed by X-ray scattering measurements and through the temperature dependence of various physical properties for the MPTBp's. The role of the W displacements within the WO3-type slabs, in two modulated structures (m = 4 and m = 10), already solved, is discussed. Finally, the complexity of the structural aspects of DPTBh's is explained on the basis of the average structures which are the only ones solved.
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25

Wang, Li Ge, Guo Qing Li, Yuan Rong Hu, Wei Gou, and Meng Shi. "Study on the Structure and Electrochromism of WO3 and Ti-Doped WO3 Films." Key Engineering Materials 373-374 (March 2008): 726–29. http://dx.doi.org/10.4028/www.scientific.net/kem.373-374.726.

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WO3 and Ti-doped WO3 electrochromic films were prepared by mid-frequency dual-target magnetron sputtering method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and spectrophotometer were used to characterize the structure, morphology, composition and transmittance properties of the films, respectively. The results show that this method is available to deposit WO3 and Ti-doped WO3 electrochromic films. The as-deposited films prepared at room temperature are amorphous and display good transmittance. The difference value of transmittance between the bleached and coloration states of WO3 film is above 60% at 633nm. Ti-doped WO3 films have smoother surface and smaller grains than undoped ones. Moreover, the crystalline temperature increases after doping titanium, because the titanium atoms influence the lattice distortion of the WO3 films. So it is more convenient for Li+ ions to inject into films and can enhance the response speed and stability of Ti-doped WO3 electrochromic films.
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26

Salleh, Fairous, Alinda Samsuri, Tengku Shafazila Tengku Saharuddin, Rizafizah Othaman, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Temperature-Programmed and X-Ray Diffractometry Studies of WO3 Reduction by Carbon Monoxide." Advanced Materials Research 1087 (February 2015): 73–76. http://dx.doi.org/10.4028/www.scientific.net/amr.1087.73.

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Tungsten (VI) oxide (WO3) reduction by carbon monoxide were examined using temperature-programmed reduction (TPR) and X-ray powder diffractometry (XRD) studies. Results show that WO3 start to reduce at 20% (CO in N2) at temperature 900 °C and the intermediate phases WO2.9 and WO2.83 were observed. The WO3 was reduced and transformed the completely to the WO2.72. As comparison, reduction by using 10% (H2 in N2), WO3 was reduced completely toWO2. The WO3 is a stable oxide because the reduction agent used to promote the reduction was not sufficient enough to reduce to zero metal tungsten.
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27

Yang, Yahui, Guanhua Jin, and Hang Li. "Photoelectrochemical Properties and Photocatalytic Activity of Fluorine-Doped Plate-Like WO3 from Hydrothermal Radio-Frequency (RF) Sputtered Tungsten Thin Films." Nano 12, no. 04 (April 2017): 1750041. http://dx.doi.org/10.1142/s1793292017500412.

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Fluorine-doped tungsten oxide (WO3) plate-like films were synthesized by hydrothermal radio-frequency (RF) sputtered tungsten (W) thin films in HF solution. The crystal structure, composition and morphology of nitrogen fluorine (F) doped WO3 were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectra (DRS) techniques. The results indicate that fluorine can be doped successfully into WO3 plate-like films by hydrothermal synthesis in hydrofluoric acid (HF) solution. The F-doped WO3 samples show stronger absorption in the UV-Vis range and a red shift in the band gap transition. Incident photon to current efficiency (IPCE) measurements carried out on photoelectrochemical cell with F-doped WO3 plate-like films as anodes demonstrate a significant increase of photoresponse in the visible region compared with undoped WO3. The photocatalytic activity under visible light irradiation for newly synthesized F-doped WO3 plate-like films was investigated by degradation of methyl orange. The photocatalytic activity of F-doped WO3 plate-like films was 3-fold enhancement compared with pure WO3 samples.
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28

Morales Gomero, Juan C., Alberto Corzo Lucioni, Hugo Alarcón Cavero, and Darío Lazo Hoyos. "SÍNTESIS Y CARACTERIZACIÓN DE PELÍCULAS DE (WO3 )n VÍA SOL-GEL MEDIANTE TÉCNICA DE RECUBRIMIENTO POR INMERSIÓN." Revista de la Sociedad Química del Perú 83, no. 4 (December 31, 2017): 420–36. http://dx.doi.org/10.37761/rsqp.v83i4.215.

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En la presente investigación se sintetizaron películas de (WO3 )n mediante la metodología Sol– Gel por técnicas de recubrimiento por inmersión (“dip coating”) utilizando Na2 WO4 como sal precursora para formar el ácido politúngstico ((WO3 )n .nH2 O), el cual por deshidratación formó el óxido ((WO3 )n que se depositó en dos sustratos diferentes: acero inoxidable 316L y vidrio conductor FTO (Fluorine doped Tin Oxide), los cuales fueron depositados bajo las mismas condiciones experimentales y posteriormente sometidos a sinterización a 400 °C por lapso de 30 minutos para ambos casos. Se observó que la película de (WO3 )n depositada sobre acero presentó mayor fotocorriente generada de 133 µAcm-2,frente a 29 µAcm-2 para la película de (WO3 )n medida por voltametría cíclica en un potenciostato (AUTOLAB PGSTAT302N) frente a la película soportada en FTO. Las películas fueron caracterizadas mediante técnicas de Espectroscopía Infrarroja con transformada de Fourier (FTIR), utilizando el espectrofotómetro FTIR SHIMADZU IR PRESTIGE 21 para reconocer los enlaces W-O-W (826 cm-1), existentes sobre la superficie del FTO y enlaces W-O-W (652 cm-1), W=O (953 cm-1), W-O (1414 cm-1) y la vibración O-H (2338 cm-1) existentes sobre la superficie del acero; Espectroscopía Raman a 532 nm para confirmar estiramientos simétricos de los enlaces W-O que no pudieron ser identificados claramente por FTIR; Difracción de Rayos X (DRX) para confirmar la estructura cristalina de las películas, encontrando una estructura predominantemente monoclínica cuya estructura base corresponde a WO3 , y un estimado aproximado de tamaño de cristalito de 27,4 nm determinado mediante la ecuación de Debye Scherrer y Energía Dispersiva de Rayos X (EDX) para el análisis elemental, arrojando una composición centesimal de 77,7 % en masa de W correspondiente a la fórmula empírica de WO3 y finalmente un análisis morfológico por Microscopía de Barrido Electrónico (SEM) que mostró la formación de capas (películas) con nanoestructuras cuyo tamaño de partícula no uniforme oscilan entre 50 y 100 nm las mismas que quedaron fuertemente adheridas a la superficie del sustrato.
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29

Gong, Li, Shanghui Chen, Weihong Zhang, Fangyan Xie, Weiguang Xie, and Jian Chen. "Photoconductive Characteristic in Individual WO3−x Nanowire." Journal of Nanoscience and Nanotechnology 11, no. 12 (December 1, 2011): 10976–80. http://dx.doi.org/10.1166/jnn.2011.4079.

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30

Ji, Yongsung, Yang Yang, Seoung-Ki Lee, Gedeng Ruan, Tae-Wook Kim, Huilong Fei, Seung-Hoon Lee, Dong-Yu Kim, Jongwon Yoon, and James M. Tour. "Flexible Nanoporous WO3–x Nonvolatile Memory Device." ACS Nano 10, no. 8 (August 9, 2016): 7598–603. http://dx.doi.org/10.1021/acsnano.6b02711.

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31

Ramadhani, Wahyuni, and Noor Hindryawati. "PEMBUATAN KOMPOSIT WO3-ZnO MELALUI REAKSI PADAT-PADAT DAN KARAKTERISASINYA." JURNAL KIMIA MULAWARMAN 18, no. 2 (May 31, 2021): 77. http://dx.doi.org/10.30872/jkm.v18i2.955.

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Pembuatan komposit WO3-ZnO melalui reaksi padat-padat telah dilakukan. Tahapan penelitian meliputi pencampuran padatan WO3 dan ZnO dengan penambahan polivinil alkohol, pengeringan, pengayakan dan pemanasan. Padatan WO3 dan ZnO sebelum dikompositkan serta komposit WO3-ZnO dikarakterisasi menggunakan instrumen X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), dan uji luas permukaan menggunakan larutan methylene blue. Hasil karakterisasi XRD menunjukkan bahwa pada sampel mengandung WO3 dan ZnO juga adanya puncak difraksi ZnWO4. Pada analisa SEM dapat diamati bahwa terdapat ukuran dan bentuk partikel yang tidak homogen. Komposit WO3-ZnO memiliki luas permukaan sebesar 110,7596 m2/g.
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32

Yang, Zhiguang, Chaosheng Zhu, Zhiqiang Hou, and Peng Peng. "Effect of oxygen vacancies on the surface morphology and structural properties of WO3– x nanoparticles." Materials Express 9, no. 7 (October 1, 2019): 773–77. http://dx.doi.org/10.1166/mex.2019.1567.

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WO3 is an essential material for energy storage and catalytical technology, the oxygen vacancies level will play an essential role in its potential application. In this paper, porous tungsten oxide (WO3–x) with various oxygen contents was quickly fabricated by a microwave plasma-enhanced chemical vapor deposition method. A detailed characterization of structure and morphology features with the plasma handling process was recorded by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy, respectively. The etching mechanism of porous WO3–x under H2 plasma was discussed based on the systemically characterization. These results will help us to design the active sites or structure in the metal oxide materials.
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33

Warsi, Al-Zoha, Fatima Aziz, Sonia Zulfiqar, Sajjad Haider, Imran Shakir, and Philips O. Agboola. "Synthesis, Characterization, Photocatalysis, and Antibacterial Study of WO3, MXene and WO3/MXene Nanocomposite." Nanomaterials 12, no. 4 (February 21, 2022): 713. http://dx.doi.org/10.3390/nano12040713.

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Tungsten oxide (WO3), MXene, and an WO3/MXene nanocomposite were synthesized to study their photocatalytic and biological applications. Tungsten oxide was synthesized by an easy and cost-effective hydrothermal method, and its composite with MXene was prepared through the sonication method. The synthesized tungsten oxide, MXene, and its composite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), energy-dispersive X-ray analysis (EDX), and Brunauer–Emmett–Teller (BET) for their structural, morphological, spectral, elemental and surface area analysis, respectively. The crystallite size of WO3 calculated from XRD was ~10 nm, the particle size of WO3 was 130 nm, and the average thickness of MXene layers was 175 nm, which was calculated from FESEM. The photocatalytic activity of as-synthesized samples was carried out for the degradation of methylene blue under solar radiation, MXene, the WO3/MXene composite, and WO3 exhibited 54%, 89%, and 99% photocatalytic degradation, respectively. WO3 showed maximal degradation ability; by adding WO3 to MXene, the degradation ability of MXene was enhanced. Studies on antibacterial activity demonstrated that these samples are good antibacterial agents against positive strains, and their antibacterial activity against negative strains depends upon their concentration. Against positive strains, the WO3/MXene composite’s inhibition zone was at 7 mm, while it became 9 mm upon increasing the concentration. This study proves that WO3, MXene, and the WO3/MXene nanocomposite could be used in biological and environmental applications.
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34

Xu, Jing, Haiying Wang, Zhongpo Zhou, and Zhaorui Zou. "Ferromagnetic Properties of N-Doped and Undoped TiO2 Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide." Materials 11, no. 10 (October 11, 2018): 1934. http://dx.doi.org/10.3390/ma11101934.

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In this work, undoped, N-doped, WO3-loaded undoped, and WO3-loaded with N-doped TiO2 rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO2 and WO3 loading onto TiO2 surface were used to increase and decrease oxygen vacancies. Various measurements were conducted to analyze the structural and magnetic properties of the samples. X-ray diffraction results showed that the N-doping and WO3 loading did not change the phase of all samples. X-ray photoelectron spectroscopy results revealed that W element loaded onto rutile single-crystal wafers existed in the form of WO3. UV-Vis spectrometer results showed that the absorption edge of WO3-loaded undoped and WO3-loaded with N-doped TiO2 rutile single-crystal wafers had red shift, resulting in a slight decrease in the corresponding band gap. Photoluminescence spectra indicated that oxygen vacancies existed in all samples due to the postannealing atmosphere, and oxygen vacancies density increased with N-doping, while decreasing with WO3 loading onto TiO2 surface. The magnetic properties of the samples were investigated, and the saturation magnetization values were in the order N-doped > WO3-loaded with N-doped > undoped > WO3-loaded undoped rutile single-crystal wafers, which was the same order as the oxygen vacancy densities of these samples. N-doping improved the saturation magnetization values, while WO3-loaded decreased the saturation magnetization values. This paper reveals that the magnetic properties of WO3-loaded with N-doped rutile single-crystal wafers originate from oxygen vacancies.
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35

Cazzanelli, E., G. Mariotto, C. Vinegoni, A. Kuzmin, and J. Purans. "Color centres and polymorphism in pure WO3 and mixed (1−x)WO3−y·xReO2 powders." Ionics 5, no. 5-6 (September 1999): 335–44. http://dx.doi.org/10.1007/bf02375997.

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36

Giovannelli, F., C. Mathieu, K. Fritsch, K. Adil, F. Goutenoire, K. Habicht, and F. Delorme. "Room-temperature synthesis of a new stable (N2H4)WO3 compound: a route for hydrazine trapping." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, no. 2 (March 7, 2019): 127–33. http://dx.doi.org/10.1107/s2052520619000064.

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A new (N2H4)WO3 compound has been obtained by mixing WO3 and aqueous hydrazine solution at room temperature for 24 h. The reaction is catalyzed by the presence of lithium. X-ray, synchrotron and neutron diffraction techniques have shown that the material crystallizes in trigonal space group P3221 (No. 154). Chains of distorted WO4 tetrahedra extend along the a axis of the unit cell, linked by a corner-sharing oxygen atom: the N2H4 are in the voids between them. The thermal characterization shows that this new compound is stable up to 220°C, greatly beyond the boiling point of N2H4 (114°C); thus making it a promising candidate for catalysis or trapping applications.
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37

Ruf, Ch, K. Bärner, and R. Braunstein. "Permanent blue coloration of (Li2B4O7)1-x(WO3)x-glasses." Solid State Communications 54, no. 1 (April 1985): 111–14. http://dx.doi.org/10.1016/0038-1098(85)91046-4.

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38

Sreesattabud, T., Anucha Watcharapasorn, and Sukanda Jiansirisomboon. "Fabrication and Characterization of Sol-Gel Derived PZT/WO3 Ceramics." Advanced Materials Research 55-57 (August 2008): 369–72. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.369.

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Lead zirconate titanate/tungsten oxide (PZT/WO3) ceramics were prepared from the powders synthesized by a modified triol sol-gel processing method. In this study, the starting materials used for synthesis of PZT-sol were zirconium (IV) propoxide, titanium (IV) isopropxide, lead (II) acetate trihydrate and 1,1,1,- tris (hydroxymethyl) ethane. To prepare PZT/xWO3 powders (where x = 0, 0.5, 1 and 3 wt%), nano-sized WO3 was ultrasonically dispersed and mixed with the PZT sol, dried and calcined at 600°C for 4 h. X-ray diffraction results indicated that fully crystallized powders were obtained. Phase characterization suggested that at high WO3 concentration, the reaction between PZT and WO3 occurred during the calcination process. To prepare PZT/xWO3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the content of WO3 significantly affected tetragonal-to-rhombohedral phase transition. Microstructure of thermally etched samples showed that increasing the content of WO3 decreased grain size of the ceramics.
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39

Niu, Xianjun, Yien Du, Jing He, Xiaodong Li, and Guangming Wen. "Hydrothermal Synthesis of Co-Exposed-Faceted WO3 Nanocrystals with Enhanced Photocatalytic Performance." Nanomaterials 12, no. 16 (August 22, 2022): 2879. http://dx.doi.org/10.3390/nano12162879.

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In this paper, rod-shaped, cuboid-shaped, and irregular WO3 nanocrystals with different co-exposed crystal facets were prepared for the first time by a simple hydrothermal treatment of tungstic acid colloidal suspension with desired pH values. The crystal structure, morphology, specific surface area, pore size distribution, chemical composition, electronic states of the elements, optical properties, and charge migration behavior of as-obtained WO3 products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), fully automatic specific surface area and porosity analyzer, UV–vis absorption spectra, photoluminescence (PL) spectra, and electrochemical impedance spectroscopy (EIS). The photocatalytic performances of the synthesized pHx-WO3 nanocrystals (x = 0.0, 1.5, 3.0, 5.0, and 7.0) were evaluated and compared with the commercial WO3 (CM-WO3) nanocrystals. The pH7.0-WO3 nanocrystals with co-exposed {202} and {020} facets exhibited highest photocatalytic activity for the degradation of methylene blue solution, which can be attributed to the synergistic effects of the largest specific surface area, the weakest luminescence peak intensity and the smallest arc radius diameter.
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40

Yang, Xinli, Nan Wu, Yongxia Miao, and Haobo Li. "Modification Effects of B2O3 on The Structure and Catalytic Activity of WO3-UiO-66 Catalyst." Nanomaterials 8, no. 10 (September 30, 2018): 781. http://dx.doi.org/10.3390/nano8100781.

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Tungsten oxide (WO3) and boron oxide (B2O3) were irreversibly encapsulated into the nanocages of the Zr-based metal organic framework UiO-66, affording a hybrid material B2O3-WO3/UiO-66 by a simple microwave-assisted deposition method. The novel B2O3-WO3/UiO-66 material was systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray phosphorescence, and Fourier transform infrared (FTIR)-CO adsorption methods. It was found that WO3 and B2O3 were highly dispersed in the nanocages of UiO-66, and the morphology and crystal structure of UiO-66 were well preserved. The B2O3 species are wrapped by WO3 species, thus increasing the polymeric degree of the WO3 species, which are mainly located in low-condensed oligomeric environments. Moreover, when compared with WO3/UiO-66, the B2O3-WO3/UiO-66 material has a little weaker acidity, which decreased by 10% upon the B2O3 introduction. The as-obtained novel material exhibits higher catalytic performance in the cyclopentene selective oxidation to glutaraldehyde than WO3/UiO-66. The high catalytic performance was attributed to a proper amount of B2O3 and WO3 with an appropriate acidity, their high dispersion, and the synergistic effects between them. In addition, these oxide species hardly leached in the reaction solution, endowing the catalyst with a good stability. The catalyst could be used for six reaction cycles without an obvious loss of catalytic activity.
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41

Hindryawati, Noor, Aman Sentosa Panggabean, Dirgarini Julia Nurlianti Subagyono, Rinda Anisyah Putri, Prilianda Kusmiaty, and Gaanty Pragas Maniam. "Modification of Spent Bleaching Earth with WO3 and the Application for Photocatalytic Degradation of Waste Dyestuff under Solar Light." Jurnal Bahan Alam Terbarukan 8, no. 2 (December 7, 2020): 84–89. http://dx.doi.org/10.15294/jbat.v8i2.22023.

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Degradation of blue dye waste in Sarong Samarinda production using WO3-bleaching earth (BE) has been conducted. Structural and morphological characterization has conducted using X-ray diffraction (XRD), and Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX). The X-ray diffraction results show the mineral on bleaching earth is rectorite dioctahedral mica layer and dioctahedral smectite with a ratio 2:1. The WO3 pattern is appeared after the calcination. After calcination at 500°C, the WO3 is deposited homogeneously on the BE surface. The catalytic performance of WO3-BE for photodegradation of the blue dye waste under the solar light is 99.85 % within 1 h.
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42

Zhuiykov, Serge. "Improved Functional Capabilities of Quasi-Two-Dimensional Tungsten Oxide Nanostructures." Key Engineering Materials 689 (April 2016): 55–59. http://dx.doi.org/10.4028/www.scientific.net/kem.689.55.

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Electrical properties and morphology of orthorhombic β–WO3 nano-flakes with thickness of ~7-9 nm were investigated at the nanoscale using energy dispersive X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNATM). CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nano-flakes synthesized via a two-step sol-gel-exfoliation method. It was determined that β–WO3 nano-flakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro- and nano-structured WO3 synthesized at alternative temperatures.
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43

Nguyen Thi Phuong Le, Chi, Phuong Tran Thi Thu, The Do Minh, Quoc Nguyen Tri, Binh Nguyen Thi Thanh, Hien Tran Thi Thu, Tung Mai Hung Thanh, Mai Nguyen Vu Ngoc, Dieu Phan Thi, and Cam Nguyen Thi Dieu. "Synthesis of WO3/Ag3VO4 photocatalyst with enhanced visible light efficiency photocatalysis." Vietnam Journal of Catalysis and Adsorption 11, no. 3 (October 16, 2022): 70–75. http://dx.doi.org/10.51316/jca.2022.053.

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WO3/Ag3VO4photocatalyst was synthesized for benefiting the visible region of solar spectrum for degradation of antibiotic pollutant. The prepared catalyst was characterized by using scanning electron microscope (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and energy-dispersive X-ray spectroscopy (EDX). The photocatalytic performance of material was evaluated by the photoredution of degradation of Amoxicillin (AMX) antibiotic under visible light. Results show that the obtained WO3/Ag3VO4photocatalyst can significantly enhance photocatalytic activity in comparison with the pure WO3 and Ag3VO4. The enhanced photocatalytic activity of WO3/Ag3VO4 was predominantly attributed to the synergistic effect which increased visible-light absorption and facilitated the efficient separation of photoinduced electrons and holes.
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44

Kumar, Channagiri Mohankumar Praveen, Manjunath Patel Gowdru Chandrashekarappa, Raviraj Mahabaleshwar Kulkarni, Danil Yurievich Pimenov, and Khaled Giasin. "The Effect of Zn and Zn–WO3 Composites Nano-Coatings Deposition on Hardness and Corrosion Resistance in Steel Substrate." Materials 14, no. 9 (April 27, 2021): 2253. http://dx.doi.org/10.3390/ma14092253.

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Pure Zn (Zinc) and its Zn–WO3 (Zinc–Tungsten trioxide) composite coatings were deposited on mild steel specimens by applying the electrodeposition technique. Zn–WO3 composites were prepared for the concentration of 0.5 and 1.0 g/L of particles. The influence of WO3 particles on Zn deposition, the surface morphology of composite, and texture co-efficient were analyzed using a variety of techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) with Energy Dispersive X-ray analysis (EDX). Higher corrosion resistance and microhardness were observed on the Zn–WO3 composite (concentration of 1.0 g/L). The higher corrosion resistance and microhardness of 1.0 g/L Zn–WO3 nanocomposite coatings effectively protect the steel used for the manufacture of products, parts, or systems from chemical or electrochemical deterioration in industrial and marine ambient environments.
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45

Choi, Gwangpyo, Guanghu Jin, Si-Hyun Park, Woonyoung Lee, and Jinseong Park. "Material and Sensing Properties of Pd-Deposited WO3 Thin Films." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 3841–46. http://dx.doi.org/10.1166/jnn.2007.040.

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The physicochemical and electrical properties of Pd-deposited WO3 thin films were investigated as a function of Pd thickness, annealing temperature, and operating temperature for application as a hydrogen gas sensor. WO3 thin films were deposited on an insulating material using a thermal evaporator. X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were used to evaluate the crystal structure, microstructure, surface roughness, and chemical property of the films, respectively. The deposited films grew into polycrystalline WO3 with a rhombohedral structure after annealing at 500 °C. Adding Pd had no effect on the crystallinity, but suppressed the growth of WO3 grains. The Pd was scattered as isolated small spherical particles of PdO2 on the WO3 thin film after annealing at 500 °C, while it agglomerated as irregular large particles or diffused into the WO3 after annealing at 600 °C. PdO2 reduction under H2 and reoxidation under air were dependent on both the Pd deposition thickness and annealing conditions. The WO3 thin film with a 2-nm-thick Pd deposit showed a good response and recovery to H2 gas at a 250 °C operating temperature.
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46

Cheng, Xiao Fang, Hong Wu Feng, and Yan Qin Wang. "Enhanced Photoelectrochemical Performance of Fe-Doped WO3 Film Electrode under Visible Light." Key Engineering Materials 531-532 (December 2012): 230–33. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.230.

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WO3 and Fe-doped WO3 thin films were prepared on Indium-Tin Oxide (ITO) glass substrates by a dip-coating. The samples were characterized by photoelectrochemistry, scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-Vis absorption spectroscopy, respectively. The result shows that the doping of Fe influenced absorption performance, and then influenced the catalytic performance. Compared with pure WO3, Fe-doped WO3 exhibited enhanced higher photoelectrochemical(PEC) performance and photocatalytic activity. The effect of doping concentration on the photocurrent was studied. It was found that the photocurrent under visible light displayed the highest values for 2% Fe-WO3 films annealed at 400 °C. The photocatalytic activity of the Fe-doped WO3 was evaluated in the methylene blue(MB) degradation under visible light illumination. The experiments demonstrated that MB could be efficiently degraded using the doped WO3 electrode as the photoanode which showed a higher activity than pure WO3. This provides a novel method for increasing the photon electric conversion efficiency of WO3 thin film electrodes.
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47

Manciu, Felicia S., Jose L. Enriquez, William G. Durrer, Young Yun, Chintalapalle V. Ramana, and Satya K. Gullapalli. "Spectroscopic analysis of tungsten oxide thin films." Journal of Materials Research 25, no. 12 (December 2010): 2401–6. http://dx.doi.org/10.1557/jmr.2010.0294.

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We present a detailed study of the morphology and composition of tungsten oxide (WO3) thin films, grown by radio frequency magnetron reactive sputtering at substrate temperatures varied from room temperature (RT) to 500 °C, using infrared (IR) absorption, Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). This work includes valuable new far-IR results about structural changes in microcrystalline WO3. Both IR absorption and Raman techniques reveal an amorphous sample grown at RT and initial crystallization into monoclinic structures for samples grown at temperatures between 100 and 300 °C. The Raman spectra of the samples grown at high temperatures indicate, apart from the monoclinic structure, a strain effect, with a distribution revealed by confocal Raman mapping. XPS indicates that the film surface maintains the stoichiometry WOx, with a value of x slightly greater than 3 at RT due to oxygen contamination, which decreases with increasing temperature.
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48

Kalanur, Shankara S., and Hyungtak Seo. "Improving Photo-Electrochemical Water Oxidation Response of WO3 By Mo Doping." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1897. http://dx.doi.org/10.1149/ma2018-01/31/1897.

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Photoelectrochemical (PEC) solar-fuel conversion is a promising approach to provide clean and storable fuel (hydrogen) directly from sunlight and water. Direct photo-electrolysis in PEC water splitting is a more elegant and potentially cheaper approach because it consists of simultaneous function of both light harvesting and electrolysis in a single device. WO3 is an indirect band gap semiconductor (E g ≈ 2.6–2.8 eV) capable of capturing approximately 12% of the solar spectrum. Due to its band gap, WO3 is considered as more suitable material than TiO2 for photoelectrochemical water splitting application. WO3 photoanode has a theoretical maximum conversion efficiency of solar energy into H2 of about 4.8% in photoelectrochemical water-splitting device. Band gap engineering for tungsten oxide (WO3) is necessary to narrow its band gap and increase light absorption ability for improved photoelectrochemical (PEC) properties. Doping WO3 with foreign atoms is very efficient strategy to tailor its band gap through modification in the band edge positions. In this work, we have demonstrated a facile hydrothermal method for the fabrication of band gap tuned WO3 thin films for PEC water splitting applications. The physical properties of synthesized Mo doped WO3 thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDS), UV-Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). Systematic studies were performed to investigate the presence of Mo in the WO3 thin films. The characterization result shows that doping of Mo into WO3 results significant change in the morphology without changing the crystal structure. Uniform distribution of Mo was observed in WO3 by elemental mapping and the approximate quantity of Mo dopant was confirmed using EDS analysis in TEM. The incorporation of Mo into WO3 reduces the band gap of WO3 and increases its light absorption ability. Above all, From XPS valence band edge analysis, we confirm that, substitution Mo into WO3 leads to the shift in the conduction band minimum downwards without any significant change in valence band maximum with respect to fermi level (Figure a). Mo doped WO3 electrodes exhibited higher photocurrent than the un-doped samples under simulated 1.5 AM sunlight without an added water oxidation catalyst (Figure b). Furthermore, in comparison to un-doped WO3 electrodes, Mo doped electrodes exhibit higher IPCE values and showed slight red shift in the onset wavelength (Figure c). Impedance measurements show that Mo doping improves electrical conductivity. The procedure proposed here, demonstrates a simple and systematic approach for the fabrication of band gap tailored WO3 photoanodes by Mo doping for efficient PEC water splitting. Overall, this work is expected to have a relevant influence on future research toward fabricating doped WO3 thin films for improving the PEC. Figure 1
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49

Jin, Xiao Bo, Guang Ming Wu, Guo Hua Gao, Wei Feng, Zeng Hai Zhang, and Jun Shen. "Mechanism of Annealing Treatment Effect on the Gasochromic Properties of WO3 Bulks and Films." Key Engineering Materials 537 (January 2013): 179–83. http://dx.doi.org/10.4028/www.scientific.net/kem.537.179.

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Nanostructural WO3 materials exhibit excellent gasochormism performance under the action of the hydrogen gas. In this paper, we study the mechanism of annealing treatment effect on the gasochromic properties both of the WO3 bulks and WO3 films. WO3 bulks were prepared from WO3 sol and dried under ambient pressure, which was previously synthesized via sol-gel method. The WO3 films were prepared using dip-coating method. UV-visible spectroscopy, Raman spectroscopy, Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction spectra (XRD) were utilized to investigate components, structures and gasochromic properties. And we find that the mechanism of the thermal treatment on the gasochromic performance depends on H+ diffusion velocity which largely relies on the structural water content.
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50

Nguyen, Thi Hai Quyen, Florian Eberheim, Sophie Göbel, Pascal Cop, Marius Eckert, Tim P. Schneider, Lukas Gümbel, Bernd M. Smarsly, and Derck Schlettwein. "Enhancing the Spectroelectrochemical Performance of WO3 Films by Use of Structure-Directing Agents during Film Growth." Applied Sciences 12, no. 5 (February 23, 2022): 2327. http://dx.doi.org/10.3390/app12052327.

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Thin, porous films of WO3 were fabricated by solution-based synthesis via spin-coating using polyethylene glycol (PEG), a block copolymer (PIB50-b-PEO45), or a combination of PEG and PIB50-b-PEO45 as structure-directing agents. The influence of the polymers on the composition and porosity of WO3 was investigated by microwave plasma atomic emission spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, and gas sorption analysis. The electrochromic performance of the WO3 thin films was characterized with LiClO4 in propylene carbonate as electrolyte. To analyze the intercalation of the Li+ ions, time-of-flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy were performed on films in a pristine or reduced state. The use of PEG led to networks of micropores allowing fast reversible electrochromic switching with a high modulation of the optical transmittance and a high coloration efficiency. The use of PIB50-b-PEO45 provided isolated spherical mesopores leading to an electrochromic performance similar to compact WO3, only. Optimum characteristics were obtained in films which had been prepared in the presence of both, PEG and PIB50-b-PEO45, since WO3 films with mesopores were obtained that were interconnected by a microporous network and showed a clear progress in electrochromic switching beyond compact or microporous WO3.
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