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Wyświetlanie 1-10 z 18
Tytuł:
Synthesis, Characterization and Sensing Behavior of WO₃ Nanocrystalline Powder for Toluene Vapor
Autorzy:
Boran, F.
Çetinkaya, S.
Tematy:
tungsten oxide
direct precipitation technique
toluene
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:
https://bibliotekanauki.pl/articles/1031559.pdf  Link otwiera się w nowym oknie
Opis:
Tungsten oxide (WO₃) nanocrystalline powder was successfully synthesized by direct precipitation technique starting from sodium tungstate dehydrate (Na₂WO₄·2H₂O) as precursor at 80°C for 48 h. The morphological characteristics, distribution, and crystallite size of WO₃ nanocrystalline powder were analysed by transmission electron microscopy, X-ray diffraction, and the Fourier transform infrared spectroscopy. According to transmission electron microscopy results, the mean particle size of WO₃ nanocrystalline powder was approximately determined as 41.7 nm. The gas sensing performance of WO₃ nanocrystalline powder for saturated toluene vapor was measured by two probe resistivity unit in a closed vessel at room temperature. In addition, WO₃ nanocrystalline powder was able to respond the lowest concentration of 500 ppm. The results showed that the sample exhibited high sensitivity (93%) and good response reproducibility (0.93+5.5%) for toluene vapor.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of a Novel Silver-Based Electrical Contact Composites and Assessment of Its Mechanical and Electrical Properties
Autorzy:
Kumar, Praveen S.
Senthil, S. M.
Parameshwaran, Rathinasamy
Rathanasamy, Rajasekar
Tematy:
silver tin oxide
electrical contact
composites
tungsten oxide
conductivity
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/2049131.pdf  Link otwiera się w nowym oknie
Opis:
The electrical contactors play a crucial role in closing the circuit in many power distribution components like overhead lines, underground cables, circuit breakers, transformers, and control systems. The failure in these components mainly occurs due to the break-down of contactors due to the continuous opening and closing action of contacts. Silver (Ag)-based oxide contact materials are widely used in practice, among which silver tin oxide (AgSnO2) is most common. An attempt is made in increasing the performance of AgSnO2, by adding Tungsten Oxide (WO3) in various weight proportions, thus finding the optimal proportion of AgSnO2WO3 to have increased mechanical and electrical performances. All the composite samples are fabricated in-house using powder metallurgy process. The assessment of physical and electrical properties namely, density, hardness, porosity, and electrical conductivity, showed that 90%Ag-8.5%SnO2-1.5%WO3 composite yielded superior results. With help of morphological tests, wear characteristics are also investigated, which showed that 90%Ag-8.5%SnO2-1.5%WO2 composite has a wear coefficient of 0.000227 and a coefficient of friction of 0.174 at an optimized load of 10 N and sliding velocity of 0.5 mm/s.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrothermal surface engineering of anodic $WO_3$ photoelectrode by simultaneous iron doping and $Fe_3O_4/FeWO_4$ formation
Autorzy:
Sulka, Grzegorz
Kotarba, Sebastian
Syrek, Karolina
Pisarek, Marcin
Piecha, Daniel
Chatterjee, Piyali
Opis:
This study reports a hydrothermal surface modification approach to porous anodized $WO_{3}$ to enhance its photoelectrochemical water oxidation performance. This results in the Fe doping of monoclinic $WO_{3}$ and the simultaneous formation of Fe-containing phases, such as $FeWO_{4}$ and $Fe_{3}O_{4}$. The photocurrent generated at the surface-engineered electrodes was double that of pure $WO_{3}$ with long-term stability. The enhancement is attributable to the creation of oxygen vacancies due to Fe doping and the formation of the heterojunction between $WO_{3}$ and $FeWO_{4}$, a p-type semiconductor, which likely improved the charge carrier lifetime and charge transfer properties. Incident photon to current efficiency (IPCE) measurements revealed enhanced visible light performance, supported by the observed red shift in the light absorption edge. This work is one of the few explorations of $WO_{3}$ photoanodes with an opaque metal substrate that involves fabrication of a light-facing overlayer at the surface. Characterization of the fabricated electrodes was carried out using X-ray diffraction (XRD), scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and diffuse reflectance spectroscopy (UV–Vis DRS). Photoelectrochemical studies were conducted using linear voltammetry, amperometry, and electrochemical impedance spectroscopy (Nyquist, Bode, and Mott–Schottky plots).
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Novel anodic $WO_3-SeO_2-CuO$ photoelectrode operating under solar illumination for water-splitting applications
Autorzy:
Sulka, Grzegorz
Pisarek, Marcin
Liu, Lifeng
Gurgul, Magdalena
Syrek, Karolina
Zych, Marta
Gondek, Łukasz
Palowska, Renata
Opis:
Anodic tungsten oxide-based materials were tested as photoanodes in photoelectrochemical (PEC) water-splitting experiments. For the first time, we present the effect of selenization on the morphology, composition, and PEC properties of $WO_{3}-W_{18}O_{49}$ and $WO_{3}-WSe_{2}$ materials. Additionally, these substrates underwent copper electrodeposition followed by re-annealing to form novel, highly efficient $WO_{3}-SeO_{2}-CuO$ composite photoelectrodes. A comprehensive investigation of their morphology, chemical composition, optical properties, and photoelectrochemical performance was conducted based on the data gathered from Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Raman Spectroscopy (RS), X-ray Photoelectron Spectroscopy (XPS), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS), Mott-Schottky analysis, and PEC experiments. Results showed that the heterojunction-based electrode exhibited two fold increase in the PEC response of the photoanode before modification with copper compounds and nearly seven times the response of $WO_{3}-CuO$ materials.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Simulation of ion transport through poly(ethylene oxide) loaded with lithium perchlorate
Autorzy:
Munn, R. W.
Eilmes, Andrzej
Sterzel, Mariusz
Scarle, S.
Opis:
A hierarchical approach is used to simulate lithium ion motion through poly(ethylene oxide) loaded with lithium perchlorate, alone and with a tungsten oxide (WO3) interface to model an electrochromic smart window assembly. The structure of the polymer is simulated using commercial software. Relaxation of the polymer is allowed on a lattice on which the lithium ions move as a lattice gas. Polarization and van der Waals energy changes are calculated for an added lithium ion at each lattice point. The structure and energy are also calculated in the presence of the WO3 interface. Ion transport is simulated in a kinetic Monte Carlo method, with and without an electric field. During runs at 300 K without the WO3 interface, with a field the lithium ions move 35 Å along it and 3–7 Å across it but without a field they move 2–5 Å; these distances vary with temperature as expected for activated hopping. Ions explore their immediate neighbourhood, occasionally jumping to an adjacent neighbourhood along, across or sometimes against the field, thus circumventing regions where transport is hindered. With the WO3, the lithium ions tend to accumulate at the interface, producing a repulsive potential that reduces ion movement.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Enhanced photoelectrochemical water splitting activity of porous anodic $WO_3$ photoelectrodes decorated with $FeWO_4$ nanoparticles
Autorzy:
Sulka, Grzegorz
Szczerba, Mateusz
Pisarek, Marcin
Piecha, Daniel
Chatterjee, Piyali
Marzec, Mateusz M.
Uchacz, Tomasz
Opis:
Only a few strategies have been reported to overcome the limitations of tungsten trioxide $(n-WO_{3})$ photoanode fabricated via anodic oxidation of metallic tungsten foil for efficient photoelectrochemical (PEC) water splitting. This work presents a method for synthesizing pure iron tungstate $(p-FeWO_{4})$ nanoparticles (∼37 nm size) via a hydrothermal process, followed by their application as co-catalyst through spin coating onto porous anodic $WO_{3}$ (∼351 nm total thickness). A thin $FeWO_{4}$ layer was essential to ensure sufficient light exposure of the underlaying $WO_{3}$ during front illumination. Due to the high crystallinity of FeWO4 and the favorable band alignment between these two semiconductors, the modified $WO_{3}$ exhibited suppressed charge carrier recombination and enhanced charge separation and transfer. As a result, the modified photoanode achieved a stable photocurrent density up to 1.5 times higher than that of pristine $WO_{3}$ under simulated solar illumination with practically unchanged onset potential. Notably, performance under visible light also improved, although no significant red shift of absorption edge (band gap of ∼2.9 eV) was noted. The results demonstrated high reproducibility, and we emphasize the significance of this approach for $WO_{3}$ photoanodes on opaque substrates, as it should be easily adaptable to $WO_{3}$ electrodes fabricated by any technique.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Stable solar water splitting enabled in anodic $W/WO_3$ nanorod based electrodes by hydrothermal engineering
Autorzy:
Sulka, Grzegorz
Chernyayeva, Olga
Szczerba, Mateusz
Piecha, Daniel
Chatterjee, Piyali
Gondek, Łukasz
Uchacz, Tomasz
Opis:
The stability of $WO_{3}$ photoelectrodes in neutral media remains a significant challenge, particularly for those fabricated by anodic W oxidation. We report a simple, one-step hydrothermal treatment that transforms porous anodic $WO_{3}$ into nanorods with a dispersed $FeWO_{4}$ phase. This morphological evolution combines the advantages of high-aspect-ratio structures for improved light absorption with reduced charge recombination losses. The treatment also promotes preferential $WO_{3}$ growth along the monoclinic (002) plane─known to favor water splitting. The modified electrodes exhibited considerable photoluminescence quenching, significantly enhanced charge separation efficiency, and higher photon-to-current conversion, resulting in a photocurrent density that was ∼1.8 times higher at 1.0 V vs RHE. Additionally, oxygen vacancy formation during operation likely contributes to charge redistribution, mitigating surface degradation in sodium sulfate and enabling rapid stabilization of the photocurrent over several hours. Electrochemical impedance spectroscopy reveals evidence of p–n heterojunction due to integration of the tungstate phase with $WO_{3}$, extended charge carrier lifetimes, and enhanced charge transfer. This scalable surface engineering approach offers a promising route to enhance the performance and durability of anodic $WO_{3}$ for practical solar-driven water oxidation.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Integration of gold nanoparticles into $BiVO_4/WO_3$ photoanodes via electrochromic activation of $WO_3$ for enhanced photoelectrochemical water splitting
Autorzy:
Masař, Milan
Urbánek, Michal
Beranek, Radim
Elnagar, Mohamed M.
Machovský, Michal
Güler, Ali
Kuřitka, Ivo
Opis:
The development of highly efficient photoanodes is crucial for enhancing the energy conversion efficiency in photoelectrochemical water splitting. Herein, we report an innovative approach to fabricating an $Au/BiVO_{4}/WO_{3}$ ternary junction that leverages the unique benefits of $WO_{3}$ for efficient electron transport, $BiVO_{4}$ for broadband light absorption, and Au nanoparticles (NPs) for surface plasmon effects. The $BiVO_{4}/WO_{3}$ binary junction was constructed by depositing a $BiVO_{4}$ layer onto the surface of the $WO_{3}$ nanobricks via consecutive drop casting. Au NPs were subsequently integrated into the $BiVO_{4}/WO_{3}$ structure through electrochromic activation of $WO_{3}$. The optimal $BiVO_{4}$ loading for the highest-performing $BiVO_{4}/WO_{3}$ heterostructure and the light intensity dependence of the photocurrent efficiency were also determined. Flat-band potential measurements confirmed an appropriate band alignment that facilitates electron transfer from $BiVO_{4}$ to $WO_{3}$, while work function measurements corroborated the formation of a Schottky barrier between the incorporated Au NPs and $BiVO_{4}/WO_{3}$, improving charge separation. The best-performing Au NP-sensitized $BiVO_{4}/WO_{3}$ photoanode thin films exhibited a photocurrent density of 0.578 mA $cm^{–2}$ at 1.23 V vs RHE under AM 1.5G (1 sun) illumination and a maximum applied-bias photoconversion efficiency of 0.036% at 1.09 V vs RHE, representing an enhancement factor of 12 and 2.3 compared to those of pristine $BiVO_{4}$ and $WO_{3}$ photoanodes, respectively. This study presents a promising and scalable route for fabricating noble metal-sensitized, metal oxide-based nanocomposite photoanodes for solar water splitting.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Wyświetlanie 1-10 z 18

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