Letteratura scientifica selezionata sul tema "Au/WO3"
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Articoli di riviste sul tema "Au/WO3":
1
Xue, Dongping, e Zhanying Zhang. "Au-sensitized WO3 nanoparticles synthesized and their enhanced acetone sensing properties". Functional Materials Letters 11, n. 04 (agosto 2018): 1850071. http://dx.doi.org/10.1142/s1793604718500716.
Abstract (sommario):
Au-sensitized WO3 nanoparticles have been synthesized by a facile two-step hydrothermal method. The structures, morphologies and surface compositions of the materials were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The test results show that we have prepared higher purity Au-sensitized WO3 nanoparticles. The gas-sensing properties of pure and Au-sensitized WO3 nanoparticles on acetone vapor were further investigated. The results obtained show that the response-recovery time of the two samples prepared is relatively short compared to that reported in the current literature. The Au-sensitized WO3 nanoparticles are significantly more sensitive and selective than the pure WO3 nanoparticles. This may be mainly attributed to the synergy between Au and WO3. It is expected that the Au-sensitized WO3 nanoparticles thus prepared can also be used for research in other fields.
2
Minggu, Lorna Jeffery, Nurul Akmal Jaafar, Kim Hang Ng, Khuzaimah Arifin e Rozan Mohamad Yunus. "Electrodeposited WO3/Au Photoanodes for Photoelectrochemical Reactions". Sains Malaysiana 49, n. 12 (31 dicembre 2020): 3155–63. http://dx.doi.org/10.17576/jsm-2020-4912-27.
Abstract (sommario):
This work aims to study the effect of gold (Au) loading on the photoelectrochemical behavior of tungsten trioxide (WO3) photoelectrodes. The WO3 film has been fabricated via electrodeposition method with constant potential on fluorine doped tin oxide (FTO) glass substrate. The Au nanoparticle loading on WO3 films surface was also prepared by constant potential electrodeposition. Due to the small amount of Au loading, the band gap values of the plasmonized WO3 remained around 2.6 eV. However, during the photoelectrochemical analysis, the photoactivity of the plasmonized WO3 photoelectrodes improved >100% with a minimal amount of Au loading compared to the pristine WO3. The photocurrent generation was further enhanced with the presence of organic donors (methanol and formic acid). The photocurrent achieved 3.74 mA/cm2 when 1.0 M of formic acid was added. Plausible charge transfer mechanism was suggested.
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Jeffery Minggu, Lorna, Nurul Akmal Jaafar, Kim Hang Ng, Khuzaimah Arifin e Rozan Mohamad Yunus. "Electrodeposited WO3/Au Photoanodes for Photoelectrochemical Reactions". Sains Malaysiana 49, n. 12 (31 dicembre 2020): 3209–17. http://dx.doi.org/10.17576/jsm-2020-4912-32.
Abstract (sommario):
This work aims to study the effect of gold (Au) loading on the photoelectrochemical behavior of tungsten trioxide (WO3) photoelectrodes. The WO3 film has been fabricated via electrodeposition method with constant potential on fluorine doped tin oxide (FTO) glass substrate. The Au nanoparticle loading on WO3 films surface was also prepared by constant potential electrodeposition. Due to the small amount of Au loading, the band gap values of the plasmonized WO3 remained around 2.6 eV. However, during the photoelectrochemical analysis, the photoactivity of the plasmonized WO3 photoelectrodes improved >100% with a minimal amount of Au loading compared to the pristine WO3. The photocurrent generation was further enhanced with the presence of organic donors (methanol and formic acid). The photocurrent achieved 3.74 mA/cm2 when 1.0 M of formic acid was added. Plausible charge transfer mechanism was suggested.
4
Figueiredo, Nuno M., Filipe Vaz, Luís Cunha e Albano Cavaleiro. "Au-WO3 Nanocomposite Coatings for Localized Surface Plasmon Resonance Sensing". Materials 13, n. 1 (6 gennaio 2020): 246. http://dx.doi.org/10.3390/ma13010246.
Abstract (sommario):
Localized surface plasmon resonance (LSPR) gas sensors are gaining increasing importance due to their unique tuneable functional properties. Au-WO3−x nanocomposite coatings, in particular, can be outstandingly sensitive to many different gases. However, a proper understanding of their optical properties and the way in which those properties are correlated to their structure/microstructure, is still needed. In this work, Au-WO3 nanocomposite coatings, with Au contents between 0–11 atomic percent, were grown using reactive magnetron co-sputtering technique and were characterized concerning their optical response. The precipitation of Au nanoparticles in the oxide matrix was promoted through thermal annealing treatments until 500 °C. Along with the Au nanoparticles’ morphological changes, the annealing treatments stimulated the crystallization of WO3, together with the appearance of oxygen-deficient WO3−x phases. Through theoretical simulations, we have related the LSPR effect with the different structural and morphological variations (namely, size and distribution of the nanoparticles and their local environment), which were a function of the Au content and annealing temperature. Our results suggest that local voids were present in the vicinity of the Au nanoparticles, for all temperature range, and that they should be present in a wide variety of Au-WO3 nanocomposites. A theoretical study concerning the refractive index sensitivity was carried out in order to predict the optimal coating design parameters for gas sensing experiments.
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Paliwal, Ayushi, Monika Tomar e Vinay Gupta. "Thickness Dependent Optical Properties of WO3 Thin Film using Surface Plasmon Resonance". MRS Proceedings 1494 (2013): 233–38. http://dx.doi.org/10.1557/opl.2013.137.
Abstract (sommario):
ABSTRACTThe effect of tungsten oxide (WO3) thin film thickness on the surface plasmon resonance (SPR) properties have been investigated. WO3 films of varying the thickness (36 nm, 60 nm, 80 nm, 100 nm, 150 nm and 200nm) have been deposited onto Au coated prism (Au/prism) by radio frequency (RF) magnetron sputtering technique. The SPR responses of bilayer films were fitted with the Fresnel’s equations in order to calculate the dielectric constant of WO3 thin film. The variation of complex dielectric constant and refractive index with the thickness of WO3 thin film was studied.
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Székely, István, Zoltán Kovács, Mihai Rusu, Tamás Gyulavári, Milica Todea, Monica Focșan, Monica Baia e Zsolt Pap. "Tungsten Oxide Morphology-Dependent Au/TiO2/WO3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman Spectroscopy". Catalysts 13, n. 6 (17 giugno 2023): 1015. http://dx.doi.org/10.3390/catal13061015.
Abstract (sommario):
Developing highly efficient Au/TiO2/WO3 heterostructures with applications in heterogeneous photocatalysis (photocatalytic degradation) and surface-enhanced Raman spectroscopy (dye detection) is currently of paramount significance. Au/TiO2/WO3 heterostructures were obtained via heat or time-assisted synthesis routes developed by slightly modifying the Turkevich–Frens synthesis methods and were investigated by TEM, SEM, XRD, Raman spectroscopy, XPS, photoluminescence, and UV–vis DRS techniques. Structural features, such as WO3 crystalline phases, TiO2 surface defects, as well as the WO3 (220) to TiO2-A (101) ratio, were the key parameters needed to obtain heterostructures with enhanced photocatalytic activity for removing oxalic acid, phenol, methyl orange, and aspirin. Photodegradation efficiencies of 95.9 and 96.9% for oxalic acid; above 96% (except one composite) for phenol; 90.1 and 97.9% for methyl orange; and 81.6 and 82.1% for aspirin were obtained. By employing the SERS technique, the detection limit of crystal violet dye, depending on the heterostructure, was found to be between 10−7–10−8 M. The most promising composite was Au/TiO2/WO3-HW-TA it yielded conversion rates of 82.1, 95.9 and 96.8% for aspirin, oxalic acid, and phenol, respectively, and its detection limit for crystal violet was 10−8 M. Au/TiO2/WO3-NWH-HA achieved 90.1, 96.6 and 99.0% degradation efficiency for methyl orange, oxalic acid, and phenol, respectively, whereas its limit of detection was 10−7 M. The Au/TiO2/WO3 heterojunctions exhibited excellent stability as SERS substrates, yielding strong-intensity Raman signals of the pollutant molecules even after a long period of time.
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Yoo, Ran, Hyun-Sook Lee, Wonkyung Kim, Yunji Park, Aran Koo, Sang-Hyun Jin, Thang Viet Pham, Myung Jong Kim, Sunglyul Maeng e Wooyoung Lee. "Selective Detection of Nitrogen-Containing Compound Gases". Sensors 19, n. 16 (15 agosto 2019): 3565. http://dx.doi.org/10.3390/s19163565.
Abstract (sommario):
N-containing gaseous compounds, such as trimethylamine (TMA), triethylamine (TEA), ammonia (NH3), nitrogen monoxide (NO), and nitrogen dioxide (NO2) exude irritating odors and are harmful to the human respiratory system at high concentrations. In this study, we investigated the sensing responses of five sensor materials—Al-doped ZnO (AZO) nanoparticles (NPs), Pt-loaded AZO NPs, a Pt-loaded WO3 (Pt-WO3) thin film, an Au-loaded WO3 (Au-WO3) thin film, and N-doped graphene—to the five aforementioned gases at a concentration of 10 parts per million (ppm). The ZnO- and WO3-based materials exhibited n-type semiconducting behavior, and their responses to tertiary amines were significantly higher than those of nitric oxides. The N-doped graphene exhibited p-type semiconducting behavior and responded only to nitric oxides. The Au- and Pt-WO3 thin films exhibited extremely high responses of approximately 100,000 for 10 ppm of triethylamine (TEA) and approximately −2700 for 10 ppm of NO2, respectively. These sensing responses are superior to those of previously reported sensors based on semiconducting metal oxides. On the basis of the sensing response results, we drew radar plots, which indicated that selective pattern recognition could be achieved by using the five sensing materials together. Thus, we demonstrated the possibility to distinguish each type of gas by applying the patterns to recognition techniques.
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Lamichhane, Shiva, Savita Sharma, Monika Tomar e Arijit Chowdhuri. "Effect of variation in glancing angle deposition on resistive switching property of WO3 thin films for RRAM devices". Journal of Applied Physics 132, n. 13 (7 ottobre 2022): 134102. http://dx.doi.org/10.1063/5.0103236.
Abstract (sommario):
In this paper, nanostructured tungsten oxide (WO3) thin films are deposited using the RF-magnetron sputtering technique in Glancing Angle (GLAD) arrangement. Variation in the structural, morphological, optical, and resistive switching (RS) characteristics of nanostructured WO3 film is investigated as a function of GLAD angle (60°–80°). Electrical studies on nanostructured WO3 films deposited at room temperature are found to exhibit enhanced bipolar resistive-switching properties in metal–insulator–metal pattern [Au/WO3/ITO]. The RON/ROFF ratio between high and low resistance states was noted to be about 190 besides a minimum set voltage of ∼2.22 V in the case of the WO3 thin film deposited at the 70° glancing angle. A detailed current transport mechanism analysis indicates the existence of ohmic-behavior and trap-assisted space charge limited conduction as the governing mechanisms at the state of low and high applied bias, respectively. Good data-retention characteristics coupled with reproducible and fast RS capabilities obtained with Au/WO3/ITO device structure promise scope of rapid development in future RS-based novel memory device applications.
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Fauzi, Aynul Sakinah Ahmad, Nur Laila Hamidah, Shota Kitamura, Taiga Kodama, Kosuke Sonda, Ghina Kifayah Putri, Takeshi Shinkai et al. "Electrochemical Detection of Ethanol in Air Using Graphene Oxide Nanosheets Combined with Au-WO3". Sensors 22, n. 9 (21 aprile 2022): 3194. http://dx.doi.org/10.3390/s22093194.
Abstract (sommario):
Detection, monitoring, and analysis of ethanol are important in various fields such as health care, food industries, and safety control. In this study, we report that a solid electrolyte gas sensor based on a proton-conducting membrane is promising for detecting ethanol in air. We focused on graphene oxide (GO) as a new solid electrolyte because it shows a high proton conductivity at room temperature. GO nanosheets are synthesized by oxidation and exfoliation of expanded graphite via the Tour’s method. GO membranes are fabricated by stacking GO nanosheets by vacuum filtration. To detect ethanol, Au-loaded WO3 is used as the sensing electrode due to the excellent activity of gold nanoparticles for the catalysis of organic molecules. Au-WO3 is coupled with rGO (reduced graphene oxide) to facilitate the electron transport in the electrode. Ce ions are intercalated into the GO membrane to facilitate proton transport. The sensor based on the Ce doped-GO membrane combined with Au-WO3/rGO as a sensing electrode shows good electric potential difference (ΔV) responses to ethanol in the air at room temperature. The sensor signal reaches more than 600 mV in response to ethanol at 40 ppm in air, making it possible to detect ethanol at a few ppb (parts per billion) level. The ethanol sensing mechanism was discussed in terms of the mixed-potential theory and catalysis of ethanol on Au-WO3.
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Balázsi, Csaba, Radu Ionescu e Katarína Sedlácková. "Hexagonal WO3 Films with Carbon Nanotubes for Sensing Applications". Materials Science Forum 589 (giugno 2008): 67–71. http://dx.doi.org/10.4028/www.scientific.net/msf.589.67.
Abstract (sommario):
In this work, nanocrystalline hexagonal tungsten oxide was prepared by acidic precipitation from sodium tungstate solution. TEM studies of nanopowders showed that the average size of the hexagonal nanoparticles is 30-50 nm. Novel nanocomposites were prepared by embedding a low amount of gold decorated carbon nanotubes into the hex-WO3 matrix. The addition of MWCNTs lowered the temperature range of sensitivity of hex-WO3 nanocomposites to NO2 hazardous gas. The sensitivity of hex - WO3 with Au-decorated MWCNTs to NO2 is at the temperature range between 25°C and 250°C.
Tesi sul tema "Au/WO3":
1
Al, Mohammad Ahmad. "Structure et morphologie des surfaces d'Al2O3α et des films minces WO3 : application à leurs interactions avec Au". Aix-Marseille 3, 2001. http://www.theses.fr/2001AIX30011.
Abstract (sommario):
Ce travail concerne l'étude des surfaces d'oxydes (la préparation, la structure, la morphologie) et de leur interaction avec un dépôt métallique (la granulométrie et la réactivité). Les surfaces d'oxyde qui ont été utilisées sont des surfaces l'alumine et d'oxyde de tungstène. Après avoir préparé et caractérisé les surfaces substrats du point de vue cristallographique par RHEED, AFM, et AES, nous avons étudiée la croissance d'un dépôt d'or sur ces différentes surfaces utilisées comme substrats. Nous avons étudié l'influence de la structure atomique d'une surface sur la croissance de l'or et caractérisé l'interaction entre cette surface et les atomes d'or. Pour ceci nous avons examiné des dépôts d'or de différentes épaisseurs, obtenus à différentes températures sur des surfaces (1012) et (0001) d'AI2O3 stœchiométriques ou réduites. Nous avons mis en évidence des différences dans les mécanismes de croissance de l'or sur ces surfaces: sur les surface stœchiométriques la croissance s'effectue atome par atome et par coalescence des particules. Sur les surfaces réduites la croissance ne se fait qu'atome par atome. Des expériences de croissance nous avons déduit les énergies d'adsorption des atomes d'or sur ces surfaces. .This work concerns the study of the oxyde surfaces (preparation, structure, morphology) and their interaction with metallic deposit (granulometry and reactivity). The oxide surfaces which were used are the alumina surfaces and tungsten oxide. We prepared and characterized the crystallographic structure of the substrate surfaces by RHEED, AFM, and AES techniques. We studied the growth of gold deposit on these various surfaces. We studied the influence of the surface atomic structure on the gold deposit growth and investigated the interactions between the surface and the gold atoms. For that we examined gold deposits of various thicknesses, deposited at various temperatures on stoichiometric or reduced surfaces (1012 ) and (0001) of alumina. .
2
Qadri, Muhammad Usman. "Tungsten oxide nanostructures and thin films for optical gas sensors". Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/279291.
Abstract (sommario):
En aquesta tesis doctoral s’han investigat capes primes i nanostructures de WO3 per sensat òptic de gasos. S’han realitzats els estudis de la síntesis dels materials nanoestructurats, la possible fabricació del dispositiu i les propietats per la detecció dels gasos.
Han estat investigades les capes primes de WO3, amb uns grossors al voltant de les 550 nm, crescudes mitjançant RF sputtering. Aquestes capes varen ser dopades amb nanopartícules de Pt i es varen estudiar les seves propietats de sensat òptic de gas sota la influencia de H2, CO i NOx. Aquestes capes mostraren una reposta i recuperacions ràpides sota la influencia dels gasos anteriorment esmentats. Les capes no dopades de WO3 mostren una resposta òptica detectable al gas NOx, mentre que les capes dopades amb nanopartícules de Pt mostres una resposta al H2 a temperatura ambient.
De manera similar, la resposta gasocromica de les nanoagulles al gas NH3 tambe va ser investigada. Les nanoagulles de WO3 decorades amb nanopartícules de Pt i Au mostren una resposta òptica quan estan exposades a NH3 gas a temperatura ambient. És la primera vegada que es reporta la resposta òptica del WO3 a temperatura ambienti es descriu en aquesta tesis. Finalment, de manera semblant a les capes primes, el temps de detecció i recuperació de les nanoagulles als gasos; és ràpid i de l’ordre de segons.
En resum, la recerca realitzada en el si d’aquesta tesis, ha complert els objectius d’investigar i desenvolupar uns sensors òptics de gasos fets de WO3 i en forma de nanoestructures i capes primers. De manera exitosa, aquest material s’ha implementat per la detecció òptica de NH3, CO, NOx i H2. Basant-nos en aquests resultats, l’avaluació final és que el WO3 és un bon material com a candidat de futurs dispositius òptics per la detecció de gasos.En esta tesis doctoral se han investigados capas delgadas i nanoestructuras de WO3 para el sensado óptico de gases. Se han relaizado estudios de las síntesis de materiales nanoestructurados, la posible fabricación del dispositivo y las propiedades para la detección de gases. Se han investigado capas delgadas de WO3 con unos grosores cercanos a 550 nm, crecidas mediante pulverización catódica de radiofrecuencia. Dichas capas fueron dopadas con nanopartículas de Pt y se estudiaron sus propiedades para el sensado óptico de gases como el H2, Co y NOx. Estas capas mostraron un respuesta y recupèración rápidas bajo la influencia de los gases mencionados anteriormente. Las capas no dopadas de WO3 mustran una respuesta óptica mediable al NOx mientras que las dopadas con Pt muestran repsuesta al H2 a temperatura ambiente. De manera similar, la respuesta gasocrómica de nanoagujas de WO3 decoardas con nanopartículas de Pt y Au muestran una respuesta óptica a temperatura ambiente cuando se exponen a NH3. Por primera vez y en esta tesis se reporta la respuesta óptica del WO3 a temperatura ambiente. Finalmente y de manera similar a las capas delgadas, los tiempos de respuesta y recuperación de las nanoagujas de WO3 es rápido y del orden de segundos. En resumen, la investigtación que se ha desarrollado en esta tesis ha cumplido los objetivos de desarrollar sensores ópticos basados en nanomateriales de WO3. Se ha implementado la detección de NH3, CO, NOx y H2. de forma exitosa. Basandonos en estos resultados podemos concluir que el WO3 representa un buen material candiudato a ser integrado en futuros dispositivos ópticos para el sensado de gases.
n this doctoral thesis, WO3 based thin films and nanostructures have been investigated for optical gas sensing. The nano structured material synthesis, device fabrication and their gas sensing properties have been studied. WO3 thin films with thicknesses around 550 nm, grown by RF sputtering have been investigated for optical gas sensing using absorbance spectroscopy. These films were doped with Pt nanoparticles and subjected to optical gas sensing under the influence of H2, CO and NOx. These films showed fast response and recovery under the influence of mentioned gases. The response and recovery time is in the range of seconds. The bare WO3 films show a measureable optical response to NOx. The films doped with Pt nanoparticles show a response to H2 at room temperature. Similarly, the gasochromic response of WO3 nanoneedles was investigated upon the exposure to NH3. The nanoneedles decorated with Au and Pt show optical response when exposed to NH3 gas at room temperature. The optical response at room temperature of these nanoneedles is presented in this doctoral thesis for the first time. Similarly to thin films, nanoneedles have also shown a fast response and recovery time in the range of seconds. In summary, this PhD research program successfully fulfilled its objectives to investigate and develop novel WO3 optical sensors based on nanostructures and thin films. During the work the author has successfully employed this material for optically sensing the mentioned gases such as NH3, CO, NOx, and H2. The evaluation of these results indicates that WO3 is a good candidate for designing future devices for optical gas sensing.
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Chambrier, Marie-Hélène. "Analyse structurale au sein du diagramme de phase de La2O3-WO3 et exploration des propriétés de conduction ionique". Le Mans, 2009. http://cyberdoc.univ-lemans.fr/theses/2009/2009LEMA1018.pdf.
Abstract (sommario):
Une appréhension avec les outils cristallographiques permet de mettre en évidence les relations structures-propriétés si nécessaires à la compréhension des propriétés de conduction des matériaux. C’est avec ce double objectif que mes travaux de thèse ont été menés : investigations structurales et études des propriétés de conduction ionique des composés définis de structure inconnue au sein du diagramme de phase La2O3-WO3. Les structures et les microstructures de ces composés, obtenus principalement par voie de synthèse solidesolide, ont été étudiés par diffraction des rayons X, des neutrons et des électrons (Microscopie Electronique en Transmission et à Balayage) sur poudre, par analyse thermique différentielle et gravimétrique, ainsi que par résonance magnétique nucléaire du 139La. Les propriétés de conduction ionique ont été caractérisées par spectroscopie d’impédance. Le composé ß-La2WO6 (1:1), forme basse température a vu sa structure résolue de manière ab-initio. Il s’agissait du dernier membre des composés Ln2WO6 (Ln = lanthanide + Yttrium) de structure inconnue, celui-ci ne présente aucune parenté cristallographique avec les composés de même formulation. Malgré des tests d’hyper-trempe, la variété haute température n’a pu être complètement isolée. Suite à la résolution structurale ab-initio du composé La14W8O45 (53,3%mol. WO3), nous avons dû reformuler ce composé vers La18W10O57 (52,6%mol. WO3). Ce composé cristallise dans une maille hexagonale de grand volume, avec un paramètre c six fois multiple du paramètre de la maille fluorine. Les trois variétés allotropiques du composé La6W2O15 (3:2) ont été étudiées. Lors de ce travail, nous avons mis en évidence une relation de parenté structurale entre ces trois formes. Les structures des formes haute température (a > 930°C) et moyenne température (630°C < ß < 930°C) sont résolues. Lors de cette étude, nous avons mis en évidence un nouveau composé défini qui se situe à 42%mol. WO3. Ce nouveau composé présente une structure modulée (1D) très proche de la forme haute température de la phase La6W2O15. On constate l’insertion d’un oxygène supplémentaire. Enfin, le composé La10W2O21 (5:2) a également été l’objet d’une longue étude car celui-ci présente une propriété de conduction par ions O2- intéressante, à 700°C, une conductivité de l’ordre de 6×10-4 S. Cm-1 a été mise en évidence. La résolution structurale a mis en évidence une structure lacunaire à la fois dans le sousréseau anionique et dans le sous-réseau cationiqueThe aim of this work deals with the structural exploration of the La2O3-WO3 phase diagram. Indeed, like many phase diagrams, La2O3-WO3 was built in the 70s, but definite compounds structures were not determined and are still unknown. This thesis focus on La2WO6, La18W10O57, La6W2O15 and La10W2O21. These compounds are synthesized as powder by solid state reaction and characterized by X-ray, neutron powder diffraction, gravimetric and differential thermal analysis, T. E. M. And 139La N. M. R. . The structure of the low temperature form named ß-La2WO6 has been determined from laboratory X-ray diffractometer, neutron (T. O. F) and electronic diffraction data. This tungstate crystallizes in a non-centrosymetric orthorhombic space group (n°19) P212121 Z = 8, a = 7,5196(1) Å, b = 10,3476(1) Å, c = 12,7944(2) Å. La18W10O57 which presents 52. 65 WO3 mol% in the binary system La2O3-WO3 in place of the previous reported compound: La14W8O45 53. 3 WO3 mol%. The structure has been determined from synchrotron and laboratory X-ray, neutron, and electron diffraction data. This tungstate crystallizes in the non-centrosymmetric hexagonal space group (n°190) P-62c , with Z = 2, a = 9. 0448(1)Å, c= 32. 6846(3)Å. This compound presents a sub cell c’=c/6= 5. 45Å. Polytypism have been observed concerning this compound by transmission electronic microscopy, ionic conductivity and thermal expansion have been explored. For the 3 allotropic La6W2O15 forms, a structural relation have been established. The a and ß form are solved. The crystal structure of La10W2O21, which has to be reformulated (La5. 667W0. 333)LaWO14??2, is best described, on average, by a 2 x 2 x 2 anion-deficient fluorite-related superstructure cubic cell, space group F 4 3m, Z = 4, a = 11. 17932(6) Å. The La/W mixed site is nicely confirmed by 139La NMR. This compound exibits an interesting fast oxide-ion conducting properties, comparable with LAMOX at low temperature. Different from many ionics conductors, we don’t notice any temperature structural transition. Its conductivity is about 6. 4×10-4 S. Cm-1 at 700°C
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Davazoglou, Dimitrios. "Caractérisation de couches minces de WO3 préparées par CVD étude de l'effet électrochrome au sein de ces couches /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604310g.
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Abdellaoui, Ahmed. "Étude de l'effet électrochrome au sein des couches minces de MoO3 et WO3 préparées par CVD : Chemical Vapor Deposit". Montpellier 2, 1989. http://www.theses.fr/1989MON20070.
Abstract (sommario):
Des couches polycristallines de moo#3 ont ete preparees par decomposition en phase vapeur de l'hexacarbonyle de molybdene mo(co)#6. La structure et la composition des couches ont ete determinees par diffraction de rayonx x, d'electrons, microscopie electronique et retrodiffusion de particules. Les variations, en fonction des parametres de fabrication, des caracteristiques electriques (resistivite, mobilite, constante de hall,. . . ) et optiques (indices, gap) des couches ont ete etudiees. L'effet electrochrome a ete mis en evidence et caracterise dans ces couches. Les resultats obtenus et compares a ceux fournis par des couches de wo#3 preparees de la meme maniere ont permis la preparation de couches mixtes moo#3/wo#3 dont les caracteristiques electrochromes ont ete interpretees qualitativement a partir du modele de separation de bandes de hubbard-mott
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Giraud, Francois. "Approche par la microcinétique expérimentale du procédé NH3-SCR sur catalyseurs V2O5-WO3/TiO2 modèles et industriels". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10241/document.
Abstract (sommario):
La présente étude a pour objectif l'obtention d'une équation donnant la vitesse globale de la réaction (activité catalytique) de la réaction NH3-SCR sur des catalyseurs du type V2O5/WO3/TiO2 (a) utilisable pour des conditions expérimentales (pressions partielles des réactifs et des constituants du mélange gazeux et températures) réalistes des conditions des rejets gazeux des centrales à charbon et (b) capable de rendre compte des effets d'empoisonnements chimiques du catalyseur. Cette équation sera implantée dans un logiciel de modélisation de l'évolution des performances des catalyseurs industriels développé par EDF. Pour remplir ces objectifs, les outils et les procédures pour l'approche microcinétique expérimentale ont été appliqués. La caractérisation de la première étape clé qui consiste à adsorbé le réactif NH3 à la surface du catalyseur (type d'adsorption, chaleurs d'adsorption de chaque espèce) a nécessité le développement de la méthode AEIR (initialement adaptée à la caractérisation de CO adsorbé sur des particules métalliques). La réactivité des espèces NH3 adsorbées vis-à-vis des différents réactifs (H2O, NOx, O2) a ensuite été étudiée, conduisant à l'élaboration d'un mécanisme cinétique plausible. A partir de ce mécanisme, un modèle cinétique de la réaction NH3-SCR a été développé et comparé aux données expérimentales obtenues sur catalyseurs modèles et commerciaux. Dans la suite de l'étude, les impacts de plusieurs poisons sur les paramètres contrôlant la cinétique de la réaction ont été déterminés expérimentalement. Dans une dernière partie, un modèle permettant de modéliser les performances catalytique de monolithes a été développé (en intégrant le modèle cinétique mis en place au cours de cette étude) et comparé à des données expérimentalesThe aim of the study is to obtain an equation for the overall reaction rate of the NH3-SCR reaction over V2O5/WO3/TiO2 catalysts (a) used for the experimental conditions (partial pressure of components of the gas mixture and temperature) realistic conditions of discharges from coal power plant and (b) able to take into account the chemical poisoning effects of the catalyst. This equation will be implemented in software developed by EDF for modeling the evolution of the performance of industrial catalysts. To fulfill these objectives, tools and procedures for the experimental microkinetic approach were applied. The characterization of the first key step of the reagent adsorbed NH3 on the surface of catalyst (type adsorption, heats of adsorption of each species) has necessitated the development of the AEIR method (initially adapted to the characterization of CO adsorbed on metal particles). The reactivity of the NH3 adsorbed species to the various reagents (H2O, NOx, and O2) was then studied, leading to the development of plausible kinetic mechanism. From this mechanism, a kinetic model of the NH3-SCR reaction has been developed and compared to experimental data obtained on model and commercial catalysts. In the remainder of the study, the impacts of several poisons to parameters that control the kinetics of the reaction were determined experimentally. In the last part, a model of catalytic monoliths performances was developed (by integrating the kinetic model developed in this study) and compared to experimental data
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Chiu, Yungchun, e 邱詠竣. "Study of ozone sensing by using Au/TiO2-WO3 materials". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/54602757828492264779.
Abstract (sommario):
碩士靜宜大學
應用化學系
100
Exploring the reaction between materials and ozone in this study by observing the changes in resistance on the surface of the photocatalyst material when ozone adsorb. The material is TiO2-WO3 composites. TiO2 and WO3 are common metal oxide semiconductors. When they were radiated by light source with specific wavelength and absorb the energy to stimulate the electron from conduction band and holes occur in the valence band. The energy to excit electrons of materials are the band gaps, the band gap of TiO2 and WO3 are 3.2 eV and 2.6 eV,respectively. But, electrons and holes may recombine and reduce the photocatalytic effect. Aadding the noble metal Au to help the electron transfer, and reduce the probability of recombination of electrons and holes. In this study, Au/TiO2-WO3 photocatalyst material is prepared by impregnation. Add the coated agent to attach photocatalyst materials on an alumina substrate with screen printing gold electrodes, after drying and 400 ° C calcination the sensor prepare completely. The preparation method is simple and cheap. Experiment in a concentration of 2.5 ppm of ozone, UV (365nm) light source as a test to identify the TiO2 and WO3 in which proportion is the best. Further small addition of Au to enhance the sensor response. The best ratio 0.1% Au/TiO2-WO3 (3:1) composite excitation in the visible region (blue light whit wavelength 465nm), the sensor response is 64. LED blue light instead of ultraviolet light, can effectively reduce costs. Using TEM, XRD and TPR for qualitative analysis.
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HUANG, WEI-RU, e 黃韋儒. "Prepared Pd-Au/TiO2-WO3 Nanoparticle Applied in Photoreduction of CO2 into CO and CH4". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/jtvh68.
Abstract (sommario):
碩士靜宜大學
應用化學系
106
This study presents Pd-Au/TiO2-WO3 nanoparticle prepared by a hydrothermal and sol-gel method as a CO2 conversion photocatalysts. The catalysts were characterized by X-ray diffraction (XRD), Scan electron microscope (SEM), Tunneling electron microscope (TEM), XPS, BET, UV-visible and Photoluminescence (PL) instruments. The appropriate amounts of Pd and Au on TiO2-WO3 composites exhibited enhanced photocatalytic activity for CO2 reduction compared with commercial TiO2 (P25). It showed the photocatalytic CH4 production rate (39.1 μmol g-1 h-1) was 100 fold that of TiO2 (P25); moreover, a large amount of CO was produced (at a rate of 271.3 μmol g-1 h-1) was 300 fold that of TiO2 (P25). The significantly improved photocatalytic activity was not only due to the increased specific surface area (72.9 m2g-1) but also UV-vis showed a remarkable enhancement of light absorption. It owes to the incorporation Pd-Au with TiO2 the visiblelight active the UV light-responsive for increased solar energy utilization. Furthermore, PL spectra revealed that the Pd-Au content can influence the charge transfer efficiency of the Pd-Au/TiO2-WO3 composites. The quantum yield of CH4 production was calculated as 1.05 %. A CO2 reduction reaction mechanism was proposed on Pd-Au/TiO2-WO3. This study can bring new insights into designing TiO2 nanostructures for applications such as solar energy conversion and storage.
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Liu, Ying, e 劉穎. "Fabrication of WO3 photoanode decorated with Au nanoplates and its applications in photoelectrochemical water splitting". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/vfzn6w.
Abstract (sommario):
碩士國立臺灣大學
材料科學與工程學研究所
107
In the present work, we improved the photoelectrochemical (PEC) performance of tungsten trioxide (WO3) photoanode by decorating WO3 film with Au nanoplates. WO3 films were fabricated on FTO-coated glass by hydrothermal treatment and Au nanoplates were incorporated by immersing the substrates in Au nanoplates solution under different periods of time. Our study revealed that compared with pristine WO3, the Au-WO3 nanocomposite performed enhanced photocurrent density under irradiation of AM 1.5G simulated sunlight. This improved PEC performance was benefited from the extension of light absorption resulting from the surface plasmon resonance effect of the Au nanoplates at about 650 nm wavelength, which was verified by UV-vis absorption spectra. The incident photon-to-current conversion efficiency measurements revealed that photoactivity was improved after decoration of Au nanoplates on WO3. This study provided a facile method to decorate Au nanoplates on WO3 photoanodes with enhanced performance for solar energy conversion.
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LIAO, WEI-HUA, e 廖偉華. "Influence of Au NPs and K+ ion doping on the electrical and humidity-sensing properties of Au NPs- or K+ ion-doped WO3 nanoparticles". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/fq9nhy.
Abstract (sommario):
碩士中國文化大學
化學系應用化學碩士班
105
Impedance-type humidity sensors made of WO3 nanoparticles (WO3 NPs) that was added with KOH or Au nanoparticles (Au NPs). The humidity-sensing (sensitivity and linearity) and electrical properties of the WO3 NPs was improved and investigated by adding with KOH and Au NPs. Adsorption dynamic analysis and molecular mechanical calculations were used to elucidate that the sensitivity of K+ ion-added WO3 NPs was higher than that of Au NPs-added WO3 NPs. The sensor that was made of the K+ ion-doped WO3 NPs layer exhibited favorable impedance, high sensitivity, good linearity, small hysteresis, a short response/recovery time and high long-term stability over the humidity range studied. Complex impedance spectra were used to investigate the humidity-sensing mechanism of the K+ ion-added WO3 NPs layer. Keywords: Humidity sensor; WO3 nanoparticles; ion; Au NPs; Adsorption dynamic analysis; Complex impedance spectra.
Capitoli di libri sul tema "Au/WO3":
1
Mao, Jingwen, Hegen Ouyang, Shiwei Song, M. Santosh, Shunda Yuan, Zhenhua Zhou, Wei Zheng et al. "Chapter 10 Geology and Metallogeny of Tungsten and Tin Deposits in China". In Mineral Deposits of China, 411–82. Society of Economic Geologists, 2019. http://dx.doi.org/10.5382/sp.22.10.
Abstract (sommario):
Abstract Tungsten and Sn deposits in China are widely distributed in the South China block (i.e., Yangtze craton-Cathaysian block), Himalaya, Tibetan, Sanjiang, Kunlun, Qilian, Qinling, Dabie, and Sulu orogens, and Central Asian orogenic belt. Among these, the South China block hosts the majority of the mineralization with about 73% (9.943 million tonnes WO3) and 85% (6.561 million tonnes Sn) of the country’s total W and Sn resources, respectively. The W resource mainly occurs as skarn (63%), quartz-vein (17%), porphyry (17%), and greisen (3%) Sulu deposits, whereas Sn is present in skarn (81%), quartz veins that are typically tourmaline-bearing (6%), sulfide-rich veins or mantos (5%), greisen (5%), and porphyry (3%) Sulu deposits. The W and Sn mineralization formed during numerous events from Neoproterozoic to Paleocene with a peak in the period from the Middle Jurassic to Early Cretaceous, and with an uneven spatial and temporal distribution pattern. The Neoproterozoic Sn (W) deposits (850–790 Ma) occur on the southern and western margins of the Yangtze craton, the early Paleozoic W(Sn) deposits (450–410 Ma) are mainly distributed in the northern Qilian and the westernmost part of the eastern Kunlun orogens, the late Paleozoic Sn and W deposits (310–280 Ma) are mainly developed in the western part of the Central Asian orogenic belt, the Triassic W and Sn deposits (250–210 Ma) are widely scattered over the whole country, the Early Jurassic to Cretaceous W and Sn deposits (198–80 Ma) mainly occur in eastern China, and the late Early Cretaceous to Cenozoic Sn and W deposits (121–56 Ma) are exposed in the Himalaya-Tibetan-Sanjiang orogen. The petrologic characteristics of W- and Sn-related granitoids in China vary with the associated ore elements and can be divided into the Sn-dominant, W-dominant, W-Cu, and Mo-W (or W-Mo) groups. The granitoids associated with the Sn- and W-dominant magmatic-hydrothermal systems are highly fractionated S- and I-type, high-K calc-alkaline and (or) shoshonitic intrusions that show a metaluminous to peraluminous nature. They exhibit enrichments in F, B, Be, Rb, Nb, and Ta, depletions in Ti, Ca, Sr, Eu, Ba, and Zr, and strongly negative Eu anomalies. The granitoids associated with W-Cu and W-Mo deposits are of a high-K calc-alkaline to shoshonitic nature, metaluminous, depleted in Nb and Ta, and display weakly negative Eu anomalies. Granitoids associated with Sn- and W-dominant deposits are reduced, whereas those linked to W-Cu and Mo-W deposits are relatively more oxidized. The magma sources of W-dominant granitoids are ancient crust, whereas those connected with Sn, Mo-W, and W-Cu deposits are from variable mixing of ancient and juvenile crustal components. The spatial and temporal distribution pattern of W and Sn deposits in China is intimately related to the regional geodynamic evolution. The Neoproterozoic Sn deposits are associated with peraluminous, highly fractionated, and volatile-enriched (boron and fluorine) S-type granites sourced from the melting of an ancient crust in a postcollisional setting related to the assembly of the Rodinia supercontinent. The early Paleozoic W deposits are genetically associated with highly fractionated S-type granites formed during postcollisional events and were derived from the partial melting of a thickened continental crust in the context of Proto-Tethyan assembly. Granitoids associated with late Paleozoic Sn and W deposits were derived from the melting of an ancient and juvenile crust with I-type affinity associated with the closure of the Paleo-Asian Ocean. Although the Triassic W and Sn deposits are related to the assembly of Asian blocks within the Pangea supercontinent, their geologic settings are variable. Those in the South China block and the Himalaya-Tibetan-Sanjiang belt are associated with collision and magma derivation through the partial melting of a thickened continental crust, whereas in the Kunlun-Qilian-Qinling-Dabie-Sulu orogen and the Central Asian orogenic belt, a postcollisional extensional setting dominates. The Early Jurassic (198–176 Ma) W deposits, located in the northern part of northeast China, are associated with highly fractionated I-type granites derived from melting of juvenile crust and emplaced during the subduction of the Mongol-Okhotsk oceanic plate. The extensive group of Middle Jurassic to Cretaceous W and Sn deposits formed at two stages at 170 to 135 and 135 to 80 Ma. The former stage is associated with highly fractionated S- and I-type granites that are the products of partial melting of thickened crust with heat input possibly derived from a slab window associated with the Paleo-Pacific oceanic plate subduction beneath the Eurasian continent. The later stage is closely associated with NNE-trending strike-slip faults along the Eurasian continental margin and is coeval with the formation of rift basins, metamorphic core complexes, and porphyry-epithermal Cu-Au-Ag deposits. These processes, which were instrumental for the formation of a wide range of mineral deposits, can be ascribed to the regional lithospheric thinning and delamination of a thickened lithosphere and thermal erosion in a postsubduction extensional setting. The 121 to 56 Ma Sn deposits in the Himalaya-Tibetan-Sanjiang orogen are associated with S-type granite or I-type granodiorite emplacement in a back-arc extensional setting during Neo-Tethys plate subduction.
Atti di convegni sul tema "Au/WO3":
1
Ramgir, Niranjan S., S. Kailasa Ganapati, N. Datta, M. Kaur, A. K. Debnath, D. K. Aswal e S. K. Gupta. "Opposite response of CO for WO3 and Au: WO3 sensors". In SOLID STATE PHYSICS: Proceedings of the 56th DAE Solid State Physics Symposium 2011. AIP, 2012. http://dx.doi.org/10.1063/1.4710185.
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Hoel, Anders, Jesper Ederth, Peter Heszler, Laszlo B. Kish, Eva Olsson e Claes-Goeran Granqvist. "Invasion noise in nanoparticle WO3/Au thin film devices". In International Symposium on Microelectronics and MEMS, a cura di Laszlo B. Kish, Erol C. Harvey e William B. Spillman, Jr. SPIE, 2001. http://dx.doi.org/10.1117/12.454608.
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Yang, Dongfang, Bo Chen, Suwas Nikumb, Chun-Hsien Chang e Chii-Wann Lin. "Surface Plasmon Resonance Gas Sensors Using Au-WO3-x Nanocomposite Films". In 2008 Second International Conference on Sensor Technologies and Applications (sensorcomm 2008). IEEE, 2008. http://dx.doi.org/10.1109/sensorcomm.2008.29.
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Jaafar, N. A., L. J. Minggu e M. B. Kassim. "Photoelectrochemical Activity of WO3/Au in Aqueous Electrolyte with Addition of Methanol". In 3rd IET International Conference on Clean Energy and Technology (CEAT) 2014. Institution of Engineering and Technology, 2014. http://dx.doi.org/10.1049/cp.2014.1461.
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Punginsang, M., C. Liewhiran, A. Wisitsoraat, S. Phanichphant, D. Zappa, E. Comini, G. Sberveglieri e A. Ponzoni. "P2NG.5 - Selective H2S Gas Sensors Based on Au-functionalized WO3 Nanowires". In 17th International Meeting on Chemical Sensors - IMCS 2018. AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany, 2018. http://dx.doi.org/10.5162/imcs2018/p2ng.5.
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Garcia-Llamas, R., e Luis E. Regalado. "Effects of Rough Interfaces in a Thin-Film". In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/oic.1995.tha8.
Abstract (sommario):
A thin film of materials that crystalize rapidly during its growth, as in the case of flourines and oxides, present shallow surface roughness. Reflectance studies of these materials show small scattering that in general is negligeable. Studies on Pyridine/Ag (1) y WO3/Au (2) have shown resonances in the reflectance spectrum associated with the excitation of Surface Plasmons.
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Dey, Anup, Bikram Biswas e Subir Kumar Sarkar. "Comparative Study of Unmodified WO3-ZnO and Au-Modified WO3-ZnO Based Thin Film Sensor Fabrication for Enhanced CH4 Gas Sensing Performance". In 2018 IEEE Electron Devices Kolkata Conference (EDKCON). IEEE, 2018. http://dx.doi.org/10.1109/edkcon.2018.8770222.