Synthesis of Tungsten Oxide Particles by Chemical Deposition Method

Abstract

Due to the high potential of photoconductive behavior used in electrochromic and sensor devices, tungsten oxide (WO 3 ) is the most promising candidate applied for electrochromic materials, gas sensors, and dye sensitized solar cells. Adsorbing the visible blue light by tungsten oxide nanoparticles would thus be used efficiently to enhance the sun-light harvest efficiency. Recent investigations have been promoted by new methods of ultrafine powder production and their applications. Nanocrystalline tungsten oxide can be prepared by sputtering methods, gas condensation methods, and chemical deposition method. In this study, we would like to prepare of tungsten oxide nanoparticles by chemical deposition method and investigate the experimental parameters of various organic solutions and discuss the relationship between absorbance spectra and which by chemical deposition method. Purged O 2 into the various solvent (i.e. DMF and acetylacetone solution), WCl 6 was added into the solvent slowly and stirred vigorously. During the filtration process solutions were characterized and analyzed by particles size distribution, UV-visible absorption, and TEM observation. The size of tungsten oxide particles synthesized in DMF is smaller than that in acetylacetone solutions from TEM observation. These results may be related to particle sizes or agglomerated behavior of tungsten oxide. In the photochromic data, it exhibits absorbance result due to valence change of tungsten ion and photochromic effect of tungsten oxide nanoparticles. Since some papers also have been reported that the highest intensity of the solar spectrum is in the blue region, the modification of the oxide semiconductor for blue-light absorption will effectively increase the photon harvest from the incident sunlight and thus generate more electronhole pairs in addition to those from dyes. It would be appropriately applied in the design of solar cell devices.

Chiral Ceramic Nanoparticles and Peptide Catalysis

“…In another perspective, it can be treated as the reduction of a portion of W 6+ ions to W 5+ ions resulting in the possibility of W 5+ → W 6+ electron transfer upon photoexcitation. 88,89 Simultaneously, the electrons from oxygen vacancies can be injected into the solid-state electronic bands associated with the tungsten oxide lattice that encompass the entire NP. This delocalization makes these electrons more mobile and can result in their coherent oscillations, constituting plasmons.…”

“…Addition of water to the colorless anhydrous WO 3 sample (Figure A, B, curves 0) results in the formation of oxygen vacancies − (see Supporting Information) that represent local excesses of electrons and accumulate at the WO 3– x ·H 2 O surface. In another perspective, it can be treated as the reduction of a portion of W 6+ ions to W 5+ ions resulting in the possibility of W 5+ → W 6+ electron transfer upon photoexcitation. , Simultaneously, the electrons from oxygen vacancies can be injected into the solid-state electronic bands associated with the tungsten oxide lattice that encompass the entire NP. This delocalization makes these electrons more mobile and can result in their coherent oscillations, constituting plasmons.…”

Synthesis of WO3 nanostructures and their ultraviolet photoresponse properties

“…Similar to the photochromism performance, [38][39][40][41][42] water molecules in air adsorbed on the surface of the WO 3 lm and reacted rapidly with holes generated under UV light irradiation to form numerous protons (H + ) (eqn (1) and ( 2)), and subsequently the produced protons could diffuse into the tunnels and cavities of the WO 3 lattice. With the photo-generated electrons excited from the valence band to the conduction band, the protons could combine with WO 3 to form blue hydrate tungsten bronze [42][43][44][45][46] (eqn (3)). At the same time, oxygen radicals could bond together to form oxygen gas and escape into the air 38,42 (eqn ( 4)).…”

The effect of gold nanoparticles on WO3 thin film

“…Chemical spray pyrolysis method, thin films were prepared by spraying the solution on a hot glass substrate at a temperature about (250 ˚C), and the film will be formed by the chemical reaction of the prepared solution on the hot substrate. To get the finally WO 3 thin film according to the following chemical equation [11] 2WCl 6 + 3O 2 → 2WO 3 + 6 Cl 2 (2) It is necessary to leave the glass substrate on the electrical heater for one hour at least after finishing the operation of spraying to complete its oxidation and crystalline growth process. In the spray system, compressed and purified air was used as the carrier gas with a 3 kg / cm 2 pressure and the spraying solution 0.05 M concentration, the distance between the spray nozzle and the substrate was fixed at 22 cm the deposition rate is ~5 min, then the substrates can be raised.…”