FeWO4 Nanoparticles Research Articles

Synergistic adsorption&photo-Fenton degradation of meloxicam and tetracycline by hollow nanoflower-like S-scheme FeWO4/ZnIn2S4 heterojunction: Mechanism, toxicity assessment, and potential applications

The rational construction of materials with dual rapid adsorption&photo-Fenton oxidative degradation functions holds great significance in the field of removing difficult-to-degrade organics. A late-model S-scheme heterojunction photocatalyst FeWO4/ZnIn2S4 was prepared by solvothermal method in this paper. The FeWO4 nanoparticles were distributed on the surface of the hollow nanoflowers assembled by ZnIn2S4, forming heterojunction structures. Representative drug residues, tetracycline (TC) and meloxicam (MLX), were selected as targets to systematically explore the removal properties of FeWO4/ZnIn2S4. This photocatalyst exhibited suitable adsorption ability, excellent photocatalytic performance, and good photo-Fenton ability for both targets. The removal efficiency of tetracycline and meloxicam by 20-FW/ZIS reached 92.9 % and 98.7 %, respectively, through a combination of adsorption&photo-Fenton degradation, with these remarkable properties being maintained after four consecutive cycles. Based on the detection of active species and the analysis of degradation intermediates, an adsorption&photo-Fenton removal mechanism and possible degradation pathway were proposed. Escherichia coli (E. coli) inhibition experiments, combined with Toxicity Estimation Software Tool (T.E.S.T.) simulated toxicity analysis, showed that the toxicity of TC and MLX decreased significantly following the photocatalytic reaction. In brief, the newly developed multifunctional photocatalyst 20-FW/ZIS, as prepared in this paper, demonstrates great potential for effectively treating organic matter in wastewater, with promising applications for practical use.

Functional designed S-doped FeWO4 hybrid for efficient mebendazole electro-oxidation and photodegradation of Methylene Blue

Sulfur-doped FeWO4 nanoparticles were synthesized via co-precipitation followed by the calcination method. The prepared samples were characterized by various techniques such as XR, FTIR, SEM, TEM, UV-DRS, PL, XPS and CV. The XRD analysis confirmed the characteristic suggesting the monoclinic phase of the S doped FeWO4. In contrast, the flower like rod like morphology found from SEM and TEM. Additionally, the study determined the optimal parameters for achieving maximum degradation of Methylene Blue (MB) dye. The most significant degradation percentage occurred when utilizing 50 mg of S-doped FeWO4 nanoparticles per 100 mL of MB solution, exposed to visible light for 70 min. Subsequently, the Mebendazole (MBZ) drug was detected using differential pulse voltammetry, employing an S-doped FeWO4 modified GCE as working electrode. Linear responses to the MBZ drug within the absorption collection of 0.1 × 10-8 to 12.4 × 10-9 M were observed, showing a sensitivity of 4.563 µA/10-8M. The detection limit (DL) and quantification limit (QL) were calculated as 5.11 nM µA-1 and 17.54 nM µA-1, respectively, with signal-to-noise ratios of S/N=3. Finally, it shows that s-doped FeWO4 esterification process, the S-doped FeWO4 catalyst was effectively functional to create benzoic acid and convert it to ester from benzoic acid, ethanol, and H2SO4 acid for organic heterogeneous catalyst.

Construction of Bi2S3/FeWO4 Z-Scheme heterojunction for efficient photo-Fenton degradation of antibiotics: Performance and degradation mechanism

Herein, the Bi2S3/FeWO4 (BS/FWO) nanocomposite with excellent photo-Fenton activity was successfully prepared by dispersing FeWO4 nanoparticles onto the Bi2S3 nanorods using the hydrothermal method. Upon optimizing the ratio of Bi2S3 to FeWO4 in the BS/FWO photocatalyst, the degradation rate constants for tetracycline hydrochloride (TCH) and oxytetracycline (OTC) reach as high as 1.597 and 1.289 L·mg−1·min−1, respectively. These values were 5.4 and 6.1 times higher than those of pure FeWO4. The enhanced degradation performance of the BS/FWO composite could be attributed to the formed Z-scheme heterojunction, which facilitated the directional carrier transfer and inhibited the electron-hole recombination, thereby increasing the production of more reactive species. Active species capture experiments and electron paramagnetic resonance (EPR) analysis indicated that the BS/FWO heterojunction could generate superoxide radicals (·O2-) and hydroxyl radicals (·OH), which play a crucial role in the degradation of organics. Furthermore, the BS/FWO composite exhibited excellent stability across multiple reuse cycles. These findings propose a novel approach for wastewater treatment.

Synthesis of polyaniline modified FeWO4 nanoparticles for superior visible-light photocatalysis

This communication reports the development of a new high-efficiency visible-light photocatalyst by coupling p-type FeWO4 with n-type polyaniline (PANI). PANI/FeWO4 nanocomposite was synthesized through a facile composition-controllable solid liquid mixing-evaporation of solvent method. The composition and structure of the synthesized PANI/FeWO4 nanocomposite were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The photoabsorption and photogenerated charge separation and transfer performance of PANI/FeWO4 nanocomposite were compared with those of FeWO4 nanoparticles. The photocatalytic properties of PANI/FeWO4 nanocomposite and FeWO4 nanoparticles were tested in the reduction of aqueous Cr(VI) under visible-light (λ > 420 nm). The results showed that the photocatalytic activity of PANI/FeWO4 was significantly elevated compared to FeWO4. Coupling with PANI can increase the adsorption of Cr(VI), enhance the absorption of visible-light, and promote the separation and transfer of photogenerated charges of FeWO4, thus contributing to the better photocatalytic activity of PANI/FeWO4.

Effect of calcination temperatures on optical and magnetic properties of FeWO4 nanoparticles

Abstract Calcination temperature is a crucial parameter that can be easily controlled to induce a change in material properties. Herein, iron tungstate (FeWO4) was synthesized via a hydrothermal method using iron(II) sulfate heptahydrate and sodium tungstate dihydrate as precursors and calcined at the temperature between 300 oC and 700 oC. With increasing calcination temperature, the saturation magnetization of FeWO4 nanoparticles decreased from 6.6 emu/g for FeWO4 to 0.4 emu/g for FeWO4_700, whereas their band gaps increased from 1.95 eV for FeWO4 to 2.20 eV for FeWO4_700. More crystallinity and crystal defects, and morphological changes at higher calcination temperatures contributed to varying magneto-optical properties of FeWO4 nanoparticles.

Development of heterogenous electro-Fenton process with immobilized FeWO4 catalyst for the degradation of tetracycline and the treatment of crude oil tank cleaning wastewater in neutral medium

The immobilization of FeWO4 nanoparticles was carried out utilizing polytetrafluoroethylene (PTFE) as adhesion agent and Na2SO4 as pore-forming agent, to develop a novel heterogenous electro-Fenton (HEF) process for the degradation of organic pollutants in neutral medium. The immobilized ferrous tungstate (FeWO4) catalyst exhibited a certain catalytic activity towards hydrogen peroxide (H2O2) activation generating active species (OH, O2– and 1O2), by which an effective tetracycline degradation was achieved under neutral condition. The low Fe-leaching amount indicated that the immobilized FeWO4 catalyst owns high chemical stability. Based on the above results, the HEF process was developed with one super-hydrophobic carbon cathode, one titanium-based oxide anode and the immobilized FeWO4 catalyst, which exhibited favorable ability for the degradation of organic pollutants attributed to the combined action of electro-Fenton oxidation and anodic oxidation. Under the optimum conditions, for the degradation of 40 mg L–1 tetracycline, the HEF process presented 100% tetracycline removal within 60 min. Furthermore, the treatment of crude oil tank cleaning wastewater by this oxidation process for 8 h presented the chemical oxygen demand (COD) removal of 85.0% and the total organic carbon (TOC) removal of 75.2%, whereas the other typical pollutants: ammonia nitrogen (NH4+-N) and volatile phenols were removed completely. After the treatment, the oil tank cleaning wastewater can be used as the recycled water or discharged into some surface waters directly. This work shows that the HEF process characterized by easy catalyst separation can not only effectively degrade organic pollutants but avoid the production of iron sludge and the inconvenience of pH adjustment.

Facile preparation of cyclized polyacrylonitrile modified FeWO4 with superior visible-light-driven photocatalysis

This paper reported the preparation of a novel high-performance visible-light-active photocatalyst (cyclized polyacrylonitrile (CPAN)/FeWO4 nanocomposite) from inexpensive and readily available polyacrylonitrile (PAN), FeSO4·7H2O, and Na2WO4·2H2O via a facile and practical approach. For the application to photocatalytic reduction of Cr(VI), the as-prepared CPAN/FeWO4 nanocomposite demonstrated not only substantially higher photocatalytic activity than FeWO4 nanoparticles, but also fairly good durability under visible-light irradiation. Besides, the as-prepared CPAN/FeWO4 also demonstrated a high efficiency in the visible-light-driven photocatalytic reduction of Cr(VI) in dilute black chromium-plating solution. The enhanced photocatalytic activity of the as-prepared CPAN/FeWO4 photocatalyst was attributed to the formation of n-p heterojunction, which facilitated the separation and transfer of photo-induced holes and electrons. Furthermore, the photocatalytic experimental conditions also heavily influenced the Cr(VI) reduction rate over the as-prepared CPAN/FeWO4 photocatalyst. This study provided useful information on the exploitation of PAN to modify semiconductor photocatalysts to create new higher efficiency visible-light-active CPAN/semiconductor composite photocatalysts.

Rapid Degradation of Methyl Orange by Heterogeneous Fenton Process Using Fewo4 Nanocatalyst Prepared by Wet Chemical Route.

To remove the hazardous organic adulterants from the wastewater, iron tungstate nanoparticles were prepared by a simple wet chemical route. These nanoparticles characterized to be polydispersed, polycrystalline with irregular spherical morphologies without any notable impurities were used as a catalyst for heterogeneous Fenton reaction, an advanced oxidation process. Their catalytic properties, degradation efficiency, and recyclability were analyzed for methyl orange degradation, a common -reactive azo dye in an acidic aqueous. The rapid fall of absorption peak exhibits the complete degradation of dye within 50 minutes of reaction with discoloration efficiency of ~97% without any additional external exposures such as light or ultrasonic waves. In addition to this, the durability of the FeWO4 nanoparticles catalyst is proved to be maintained over five catalyst reuse cycles, which strongly suggests that at this present scenario of ecological deterioration, the chosen nanomaterial is one of the apt candidates for azo dye removal by heterogeneous dark Fenton process.

Synthesis and characterization studies of polypyrrole/iron tungstate nanocomposites for interfacial water evaporation

PPy-FeWO4 composites were synthesized by polymerization of pyrrole in presence of varying weight percentage of FeWO4 nanoparticles using FeCl3 as both catalyst and dopant. The synthesized polymer composites were characterized by FTIR, XRD, FESEM-EDAX, TEM and TGA analysis. The XRD and FTIR analysis confirmed showing near pure samples were achieved. The FESEM-EDAX and TEM studies showed the presence of FeWO4 nanoparticles which were well dispersed in the polymer matrix. The thermal degradation studies showed similar stability of polymer matrix in the presence of nanoparticles. Interfacial solar water evaporation devices were fabricated by depositing the polymer composite on floatable PU sponges. The studies revealed that 50-50 wt% PPy-FeWO4 showed maximum solar to vapour conversion up to 86% with an evaporation rate up to 1.2 kg m−2 hr−1.

Identification of M‐NH2‐NH2 Intermediate and Rate Determining Step for Nitrogen Reduction with Bioinspired Sulfur‐Bonded FeW Catalyst

AbstractThe multimetallic sulfur‐framework catalytic site of biological nitrogenases allows the efficient conversion of dinitrogen (N2) to ammonia (NH3) under ambient conditions. Inspired by biological nitrogenases, a bimetallic sulfide material (FeWSx@FeWO4) was synthesized as a highly efficient N2 reduction (NRR) catalyst by sulfur substitution of the surface of FeWO4 nanoparticles. Thus prepared FeWSx@FeWO4 catalysts exhibit a relatively high NH3 production rate of 30.2 ug h−1 mg−1cat and a Faraday efficiency of 16.4 % at −0.45 V versus a reversible hydrogen electrode in a flow cell; these results have been confirmed via purified 15N2‐isotopic labeling experiments. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M‐NH2‐NH2) on the surface of the bimetallic sulfide catalyst is the rate‐determing step for the NRR process. Therefore, this work can provide guidance for elucidating the structure–activity relationship of NRR catalysts.

Identification of M-NH2 -NH2 Intermediate and Rate Determining Step for Nitrogen Reduction with Bioinspired Sulfur-Bonded FeW Catalyst.

The multimetallic sulfur‐framework catalytic site of biological nitrogenases allows the efficient conversion of dinitrogen (N2) to ammonia (NH3) under ambient conditions. Inspired by biological nitrogenases, a bimetallic sulfide material (FeWSx@FeWO4) was synthesized as a highly efficient N2 reduction (NRR) catalyst by sulfur substitution of the surface of FeWO4 nanoparticles. Thus prepared FeWSx@FeWO4 catalysts exhibit a relatively high NH3 production rate of 30.2 ug h−1 mg−1 cat and a Faraday efficiency of 16.4 % at −0.45 V versus a reversible hydrogen electrode in a flow cell; these results have been confirmed via purified 15N2‐isotopic labeling experiments. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M‐NH2‐NH2) on the surface of the bimetallic sulfide catalyst is the rate‐determing step for the NRR process. Therefore, this work can provide guidance for elucidating the structure–activity relationship of NRR catalysts.

FeWO4/nitrogen-doped multi-dimensional porous carbon for the highly efficient and stable oxygen reduction reaction

Non-precious metal oxygen reduction catalysts still present considerable challenges in ensuring activity and stability in acidic/alkaline media. In this paper, the tungstate with excellent stability is selected as the electrocatalyst for oxygen reduction reaction (ORR). FeWO4/nitrogen-doped multi-dimensional porous carbon (FeWO4/N-MPC) catalyst was successfully synthesized by freeze-drying and rapid calcination methods. FeWO4/N-MPC exhibited a multi-dimensional porous carbon structure with uniformly distributing FeWO4 nanoparticles. The nitrogen-doped multi-dimensional porous carbon structure composed of nanofibers and nanosheets can significantly improve the transport efficiency of charge and O2 and effectively protect the FeWO4 nanoparticles, further leading to enhance catalytic activity and stability of FeWO4/N-MPC. Thus, FeWO4/N-MPC exhibited excellent catalytic performance for ORR in acidic/alkaline media. The long-term durability of FeWO4/N-MPC was also remarkably more outstanding than that of 20 wt% Pt/C catalyst in acidic/alkaline media. The long-term durability of FeWO4/N-MPC had also made it possible to apply in metal-air batteries and fuel cells.

Spectroscopic investigation on photocatalytic degradation of methyl orange using Fe2O3/WO3/FeWO4 nanomaterials.

In this study, iron oxide (Fe2O3), tungsten oxide (WO3) and iron-tungstate oxide (FeWO4) nanoparticles (NPs) were synthesized by simple precipitation, acid precipitation, and hydrothermal method respectively. All the spectroscopic analysis reveals that as-synthesized NPs are crystalline with a z-average size of 342, 313 and 373 d.nm respectively. The element compositions, shape and size of the NPs were identified with the help of SEM with EDX analysis. FTIR analysis concluded that the presence of functional groups on the surface of NPs and which responsible for capping and formation of NPs. Besides, the as-synthesized NPs have been used as a photocatalyst for the degradation of Methyl Orange (MO) dye under visible irradiation. FeWO4 NPs (98%) show more effective in the degradation of MO as compared to other NPs. Moreover, the degraded MO and its by-products were used to assess their toxicity on Vigna radiata and RAW 264.7 cell line and which were confirmed that degraded by-products were non-hazardous.

Biotemplated Synthesis of Hierarchically Porous ZnAl-CLDH/FeWO4 for Effective Removal of Dyes From Water

Biotemplating method is a promising way to obtain hierarchical materials with unique morphology and property. In the current work, a novel hierarchically porous ZnAl-CLDH (calcined layered double hydroxides)/FeWO4 had been successfully synthesized by a facile biotemplated method. The obtained samples were characterized in detail via FESEM-EDX, TEM, XRD, IR, TGA, and BET techniques. The as-synthesized ZnAl-CLDH/FeWO4 hierarchical microspheres were composed of ZnAl-CLDH nanosheets and FeWO4 nanoparticles. The obtained sample exhibited both high adsorption and visible-light photocatalytic activity toward Congo Red (CR) in water. It was found that the adsorption process was well described by the pseudo-second-order kinetic model and the Langmuir isotherm model, while the photocatalytic degradation process was well fitted to the first-order kinetics model. The enhanced photocatalytic performance was mainly due to the hierarchically porous structure that could offer more exposed active sites, as well as the unique energy band structure of heterostructures, that facilitated the efficient separation and transfer of photoinduced carriers and enhanced light harvesting. In addition, the as-prepared sample had quickly magnetic response and could be easily separated from water under an external magnetic field after wastewater treatment.

Direct Z-Scheme g-C3N4/FeWO4 Nanocomposite for Enhanced and Selective Photocatalytic CO2 Reduction under Visible Light.

Photocatalytic reduction of CO2 to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO2 reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C3N4/FeWO4 composites are prepared for higher performance and selective CO2 reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO4 nanoparticles with C3N4 nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 μmol/g/h at an ambient temperature, almost 6 times higher compared to pristine C3N4 and 15 times higher than pristine FeWO4. More importantly, selectivity for CO is 100% over other carbon products from CO2 reduction and more than 90% over H2 products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO4 and C3N4 reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron-hole pair in g-C3N4/FeWO4 but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO2 reduction into solar fuels under solar light.

One-pot synthesis of 3-hydroxy-2-oxindole-pyridine hybrids via Hantzsch ester formation, oxidative aromatization and sp3 C[sbnd]H functionalization using FeWO4 nanoparticles as recyclable heterogeneous catalyst

Synthesis of poly-substituted 3-hydroxy-2-oxindole-pyridine hybrids is reported via sp3 CH bond functionalization as key steps using FeWO4 nanoparticles as reusable heterogeneous catalyst. Formation of Hantzsch ester (DHP) followed by aromatization, and sp3 CH bond functionalization was achieved using FeWO4 nanoparticles (20mol%) at 80°C. Temperature dependent reactivity was observed for mono aldol (at 80°C) and bis aldol (at 120°C) products. The catalyst was regenerated and reused up to 6cycles without losing catalytic activity. The FeWO4 nanoparticles were also used for oxidative aromatization of different DHP derivatives and for the sp3 CH functionalization of 2-methyl pyridine.

Synthesis of magnetic FeWO4 nanoparticles and their decoration of WS2 nanotubes surface

Owing to their unique properties such as mechanical, optical, magnetic, nanomaterials attracted a great interest over the last two decades. Inorganic nanotubes, e.g. WS2, make an important class of nanomaterials with numerous potential applications. In the current work, a new synthetic strategy is developed to decorate the surface of WS2 nanotubes with FeWO4 nanoparticles. The FeWO4 nanoparticles were produced by first depositing amorphous iron oxide film onto the WS2 nanotubes’ surface and, subsequently, high-temperature annealing (600 °C). Careful analysis by electron microscopy; X-ray diffraction and other techniques were carried out. Based on these analyses, the growth mechanism of the hybrid nanostructures was elucidated. Magnetic measurements were employed to shed light on the magnetic behavior of the hybrid nanostructures. The orientation and position of the WS2 nanotubes decorated with the FeWO4 nanoparticles could be partially affected by applying a magnetic field using non-viscous solvents, like ethanol.

Fabrication of FeWO4@ZnWO4/ZnO Heterojunction Photocatalyst: Synergistic Effect of ZnWO4/ZnO and FeWO4@ZnWO4/ZnO Heterojunction Structure on the Enhancement of Visible-Light Photocatalytic Activity

One-dimensional FeWO4@ZnWO4/ZnO heterojunction photocatalysts were prepared by a two-step hydrothermal method. The heterojunction structure was formed through the dispersing of FeWO4 nanoparticles on the surface of ZnWO4/ZnO nanorods. The FeWO4@ZnWO4/ZnO photocatalyst possessed strong visible light absorption capacity. The photocatalytic activities of the prepared photocatalysts were evaluated by degradation of rhodamine B (RhB), methylene blue (MB), and phenol under visible light irradiation. Remarkably, the FeWO4@ZnWO4/ZnO composite showed superior photocatalytic activity than that of individual FeWO4 and ZnWO4/ZnO substrate. The enhanced photocatalytic activity could be attributed to the interfacial transportation of photogenerated holes between FeWO4 and ZnWO4/ZnO substrate, leading to more effective separation and faster transfer of carriers in the heterostructures, which was confirmed by photocurrent responses and photoluminescence spectral analysis. Radical trapping experiments indicated that hydro...

Polypyrrole-encapsulated iron tungstate nanocomposites: a versatile platform for multimodal tumor imaging and photothermal therapy

A versatile nanoplatform of FeWO4@Polypyrrole (PPy) core/shell nanocomposites, which was facilely fabricated by first hydrothermal synthesis of FeWO4 nanoparticles and subsequent surface-coating of polypyrrole shell, was developed as an effective nanotheranostic agent of cancer. The as-prepared nanocomposites demonstrated excellent dispersion in saline, long-term colloidal storage, outstanding photo-stability and high photothermal efficiency in solution. In particular, FeWO4@PPy exhibited efficient performance for hyperthermia-killing of cancer cells under the irradiation of an 808 nm laser, accompanied with multimodal contrast capabilities for magnetic resonance imaging, X-ray computed tomography and infrared thermal imaging in vitro and in vivo. Furthermore, the nanocomposites presented impactful tumor growth inhibition and good biocompability in animal experiments. Blood circulation and biodistribution of the nanocomposites were also investigated to understand their in vivo behaviours. Our results verified the platform of FeWO4@PPy nanocomposites as a promising photothermal agent for imaging-guided cancer theranostics.

Synthesis and Characterization of Ferrous Tungstate Nanoparticles

Highly crystalline FeWO4 nanoparticles (NPs) were synthesized via the hydrothermal synthesis method while amorphous FeWO4 NPs were prepared by the room temperature precipitation method. It was found that a dissolution-recrystallization process appeared due to the Ostwald ripening when room temperature precipitates undergo the hydrothermal process. Photocatalytic performance toward the degradation of methylene blue showed that crystalline FeWO4 NPs displayed a higher activity than amorphous samples, mainly ascribing to the substantial elimination of defects after crystallization because the defects promoted the recombination of electron-hole pairs.