Pure WO3 Nanofibers Research Articles

An excellent triethylamine sensor based on composite nanotube WO3/SnO2

Triethylamine (TEA) is a volatile organic compound, widely used in production and life. But as a strong irritating and flammable gas, it is a serious threat to people's life safety, so the development of high-performance TEA gas sensor is of great significance to human life and production. In this work, pure WO3 and WO3/SnO2 composite nanofibers were prepared by electrospinning method. The morphology and microstructure of the obtained samples were characterized by SEM, XRD, XPS, PL, etc. Then the gas sensitivity of the samples was studied. The results show that both pure WO3 nanofibers and composite nanofibers have good selectivity for TEA. But compared with pure WO3 nanofibers, WO3/SnO2 nanofibers have higher response, faster response/recovery time (14 s/22 s) and better stability. The optimal temperature is 260 °C, 20 °C lower than that of pure WO3 nanofibers, and the response to 100 ppm TEA at this temperature is about 26, which is nearly 1 times higher than that of pure WO3 nanofibers. The improvement of gas-sensitive performance is mainly attributed to the successful construction of heterojunctions to improve electron transport efficiency and the optimization of morphology and structure through the composite.

Production of CuO–WO3 hybrids and their dye removal capacity/performance from wastewater by adsorption/photocatalysis

In this study, it is aimed to develop a hybrid bi-functional material which will enable the removal of common industrial toxic dyes in wastewater via adsorption/photocatalysis reactions. For this purpose, WO3 nanofibers and CuO particles were synthesized using electrospinning and hydrothermal synthesis methods, respectively. WO3 nanofibers were combined with different amounts of CuO particles by a simple dispersion dropping technique. Structural, morphological and optical properties of the samples were characterized by XRD, Raman, FT-IR, XPS, SEM, TEM, UV–vis, and Mott-Schottky measurements. The adsorption capacity and photocatalytic behavior of the hybrids were compared with pure WO3 nanofibers under visible light irradiations. Experimental results have shown that the hybrid samples containing only 0.75 wt.% CuO could adsorb 38.4% higher and degraded 25.7% faster the methylene blue dye compared to pure WO3 nanofibers. This improved adsorption and degradation behavior of the hybrids were discussed in detail based on the structural properties, Z-scheme heterojunction formation, and using Langmuir/Freundlich isotherm and kinetic models.

Synthesis of WO3 nanofibers decorated with BiOCl nanosheets for photocatalytic degradation of organic pollutants under visible light

Notwithstanding intensive research in recent decades, the conspicuous restrictions in photocatalysts still remain as low utilization of visible light, poor charge transfer/separation, and insufficient surface active sites. Designing semiconductor heterostructures as photocatalysts is a promising approach to enhance the photocatalytic efficiency for degrading organic pollutants. In this work, a novel WO3/BiOCl p–n heterostructure photocatalyst with optimal molar ratio was successfully fabricated by growing BiOCl nanosheets on WO3 nanofibers through the electrospinning method followed with a solvothermal process. The optical properties and photoelectrochemical tests indicated that the WO3/BiOCl heterostructures possess high ability of photogenerated charge separation. The photocatalytic performance of the as-obtained materials was assessed by the degradations of rhodamine B (RhB) and phenol in water under visible light. Compared with pure WO3 nanofibers and BiOCl nanosheets, the WO3/BiOCl heterostructure catalysts showed improved photocatalytic efficiencies, and the apparent rate constant of RhB degradation is 0.259 min−1 on the optimal WO3/BiOCl(2) sample, which is about 2.3 times that of pure BiOCl (0.113 min−1). The roles of different active species in the photocatalytic system were determined by active-species-eliminating experiments, revealing that the photogenerated holes play a leading function in the degradation of organic pollutants. The enhanced photocatalysis of WO3/BiOCl(2) heterostructures results from the joint effect of high activity of BiOCl nanosheets, anti-agglomeration of WO3 nanofibers, and well-matched straddling band-structures for charge separation. This photocatalyst presents great potential in the removal of organic pollutants from aquatic environment.

Hierarchical WO3/ZnWO4 1D fibrous heterostructures with tunable in-situ growth of WO3 nanoparticles on surface for efficient low concentration HCHO detection

Hierarchical WO3/ZnWO4 1D fibrous heterostructures with tunable in-situ growth of WO3 nanoparticles on surface have been fabricated by the original one-step electrospinning technology combined with subsequent calcination process. Phase composition and morphology can be transformed from bead-like WO3 fibers to hierarchical WO3/ZnWO4 1D composites with the introduction of ZIF-8 into the precursor solution, which was mainly attributed to the combination of nucleation competition and crystal planes matching mechanisms during heat treatment. Compared with pure WO3 and WO3/ZnWO4-10%, WO3/ZnWO4-5% displayed the highest specific surface area value evaluated to be 268.57, indicating the prominent enhanced absorption behavior for targeted organic species. It is found that WO3/ZnWO4-5% composites have a response about 44.5 for 5 ppm HCHO, which was almost 8 times higher than that of sensor based on pure WO3 nanofibers at the optimal operating temperature. Meanwhile, the fast response/recovery time (12/14 s) and excellent stability characteristics (recycling, long-term, and humidity stability) towards HCHO can be also observed for WO3/ZnWO4-5% samples. The enhanced gas-sensing mechanism based on WO3/ZnWO4 composites can be ascribed to the synergistic effect of effective heterojunctions, large specific surface area, multiple reaction sites, and unique surface/interface electron transmission. The design and construction of hierarchical WO3/ZnWO4 1D materials attest to the significant potential of their use as novel gas sensors for detecting low concentration HCHO.

Porous bimetallic Mo-W oxide nanofibers fabricated by electrospinning with enhanced acetone sensing performances

Porous bimetallic Mo-W oxide (MoO3-WO3) nanofibers with different Mo/W molar ratios have been prepared via a simple electrospinning approach. The composition, surface area, porosity, as well as oxygen species absorbing capability of the bimetallic Mo-W oxide nanofibers can be reasonably tuned through the modulation of Mo/W molar ratios. The sensing results show that the Mo-W oxide nanofibers exhibit much better acetone sensing properties compared with pure WO3 nanofibers. The best sensing properties are found for Mo-W oxide nanofibers with 6% Mo/W molar ratio, showing the highest response of 26.5 towards 100 ppm acetone and the lowest detection limit of 19.2 ppb at 375 °C, which are 2.6 and 4.2 times better than those of pure WO3 nanofibers, respectively. Moreover, the Mo-W oxide nanofibers also exhibit good acetone selectivity and stability. The enhanced acetone performances of 6 mol% bimetallic Mo-W oxide nanofibers can be mainly ascribed to the synergetic effects of several factors including the generation of numerous MoO3-WO3 n-n heterojunctions, high surface area and abundant porous structure as well as high surface oxygen species absorbing capability.

Pt modified ultrafine WO3 nanofibers: A combined first-principles and experimental study

The Pt modified ultrafine WO3 (Pt/WO3) nanofibers with average diameter of 70 nm, showing excellent photoelectrochemical properties have been successfully prepared via a simple two-step technique. Pt/WO3 nanofibers with various Pt contents exhibit the excellent photocatalytic activity for Rhodamine B (RhB), better than pure WO3 nanofibers, which can be ascribed to the synergistic effect arising between Pt and WO3. Simultaneously, these highly composition-dependent with Pt/WO3 nanofibers shows the optimized photodegradation efficiency. 1%-Pt/WO3 nanofibers provide the enhanced photodegradation efficiency (93.7%) under the visible-light irradiation for 140 min. Based on the density functional theory, the first-principle calculations are performed to further explore the synergistic effect, electronic structure and photocatalytic mechanism of the as-prepared photocatalysts. This design opens up further opportunities for improving photocatalysts and understanding for the optimization of photocatalytic activity of these unique materials.

Synergistic effect of Cu-ion and WO3 nanofibers on the enhanced photocatalytic degradation of Rhodamine B and aniline solution

In this work, a series of efficient visible-light-driven WO3/Cu (II) nanofiber photocatalysts, with superior photocatalytic activities for the degradation of dyes and aniline, were prepared by electrospinning and impregnation methods. The impregnation method brought about homogeneous distribution of Cu (II) species on the surface of WO3 nanofibers. The prepared WO3/Cu (II) nanofiber photocatalysts exhibited enhanced visible-light absorption and reduced charge recombination, as compared to pure WO3 nanofibers, due to the interfacial charge transfer (IFCT) effect between the Cu (II) species and WO3. The combined benefits of the grafting Cu (II) species on the surface of WO3, in terms of optical, surface, and texture properties, led to a significant improvement in the photocatalytic activity for the degradation of Rhodamine B (Rh B) and aniline under conditions of visible light irradiation. Upon the irradiation with visible light in the presence of WO3/Cu (II)-2% photocatalyst, the concentration of Rhodamine B (Rh B) decreased from 10 mg/L to 1.5 mg/L, and that of aniline solution decreased from 5 mg/L to 0.728 mg/L over a period of 3 h. And after running five cycles, the concentration of aniline solution could decrease from 5 mg/L to 0.89 mg/L by WO3/Cu (II)-2% photocatalyst.

Fabrication of conductive graphene oxide-WO3 composite nanofibers by electrospinning and their enhanced acetone gas sensing properties

Pure WO3 and GO-WO3 composite nanofibers with different contents of conductive graphene oxide (GO) were fabricated by a facile electrospinning technique in this work. The gas sensing properties of the fabricated nanofibers were evaluated towards acetone in detail. The results revealed that the GO-WO3 composite nanofibers exhibited much higher response and faster response/recovery time in comparison with pure WO3 nanofibers. Particularly, the 1 mL GO-WO3 composite nanofibers displayed the highest response of 35.9–100 ppm acetone at 375 °C, which is 4.3 times higher than that of the pristine WO3 nanofibers. In addition, the sensor resistance was reduced by adding conductive GO into WO3 nanofibers. Good selectivity and stability to acetone were also demonstrated for the composite nanofibers. The improvement of gas sensing performances was attributed to the synergistic effects of the creation of ohmic contact between GO nanosheets and WO3 nanograins, ultrahigh surface area and strong gas adsorption capacity of GO nanosheets and special porous structural features of the GO-WO3 composite nanofibers.

Facile synthesis and gas sensing properties of La2O3–WO3 nanofibers

A series of La2O3-doped WO3 nanofibers were synthesized by an electrospinning method in this work. The structure composition and morphology of nanofibers were characterized by XRD (X-ray diffraction), field emission scanning electron microscopy (FESEM), selected area electron diffractive (SAED), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Sensors based on these nanofibers were fabricated by hot-press on the ceramic plates. The gas sensing properties of the undoped and La2O3-doped WO3 (La3+:W6+=1mol%, 3mol% and 5mol%) nanofibers were tested to various gases. The sensors based on La2O3-doped WO3 nanofibers, in which the molar ratio of La3+:W6+ is 3:100, exhibit highest response toward 100ppm acetone, having a response about 12.7, which is almost 2 times higher than that of sensor based on pure WO3 nanofibers. These results indicate that the acetone sensors based on the La2O3-doped WO3 nanofibers exhibit fast response and good repeatability characteristics, which are promising for acetone sensors which used by air-quality and environmental monitoring.

Facile synthesis and gas sensing properties of In2O3–WO3 heterojunction nanofibers

A series of In2O3–WO3 heterojunction nanofibers were synthesized via the electrospinning technique in this study. The morphological and microstructural properties of these nanofibers have been characterized by XRD (X-ray diffraction), field emission scanning electron microscopy (FESEM), selected area electron diffractive (SAED), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The gas sensing properties of the In2O3–WO3 heterojunction nanofibers were evaluated. The results indicate that the sensor based on In2O3–WO3 nanofibers, in which the molar ratio of In2O3:WO3 is 1.5:100, exhibits the largest response toward 50ppm acetone among those nanofibers, having a response about 12.9–50ppm acetone, which is almost 2.5 times higher than that of sensor based on pure WO3 nanofibers at the optimum operating temperature. What's more, the sensor can detect acetone in sub-ppm concentrations with high response, the limit of detection (LOD) of the sensor based on heterojunction nanofibers is ∼0.4ppm, which is promising for being used in noninvasive detection of illnesses.

Synthesis, Characterisation of WO3 Nanofibers and their Application in Chemical Gas Sensing

AbstractWO3 nanofibers have been produced by a simple method as electrospinnig. This is a process by which polymer nanofibers (with submicron scale diameters) can be formed when a droplet of viscoelastic polymer solution is subjected to high voltage electrostatic field. Polymer PMMA and WCl6 solution mixtures were used as precursors. The nanofiber were characterized morphologically and chemically by XPS, SEM, and XRD measurements and it was found the formation of mixed WOx/PMMA nanowires at room temperature that evolve after annealing at 300°C towards pure WO3 nanofibers as evidenced by XPS measurements. After the characterization the nanofibers have been deposited on the sensor devices to check their gas sensing properties. They show a semiconductor-like behaviour when they are heated and wide variation of the electrical resistance when they are exposure to NO2 gas.