Tungstate Nanocomposites Research Articles

HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED COMPOSITE MATERIALS FOR PHOTODEGRADATION APPLICATIONS

Metal oxide nanocomposites are a critical element in nanoscale technology. Because of their many uses, a great deal of study has involved photocatalytic materials. These photocatalytic degradation characteristics also included applications like solar-cell applications. Waste­water management was included in the photodegradation property. The following study explored the development of europium tungstate nanocomposites with titanium dioxide and how they can be used in photocatalytic applications. The synthesis was conducted using the hydrothermal method and is characterized by Fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Application experiments were conducted using four distinct dyes, namely methyl orange, methylene blue, congo red and methyl red. The photodegradation experiments were conducted using visible light emitted by a tungsten-filament lamp. Methylene blue and methyl orange degraded to 20 % and 35 % after 1 hour respectively. After 90 min, the degradation of methylene blue went down to 15 % and congo red degraded down to 9 %. With the experiment conducted, the sample showed that it had a relatively higher photodegradation property with the dyes used. The results show that the compound had better reaction with these dyes, with a degradation down to 10 %.

Nickel and cobalt-based tungstate nanocomposites as promising electrocatalysts in alkaline direct methanol fuel cells.

In this work, a non-precious group metal (non-PGM) electrocatalyst based on transition metals is introduced as a promising solution for enhancing the efficiency of direct methanol fuel cell (DMFC). Nickel-cobalt mixed tungstate was prepared using a simple co-precipitation method with different molar ratios of Ni, Co and W. The prepared materials were tested and validated using different characterization techniques. It was observed using SEM that the materials are agglomerated amorphous random circular nanocomposite structures. The electrochemical performance of the prepared electrocatalysts revealed that the best nanocomposite was the one with the Ni : Co : W ratio of 1 : 1 : 1.5 (W1.5). This composite showed a higher current density of 229 mA cm-2 towards methanol oxidation at a scan rate of 50 mV s-1 in 1 M methanol at 0.6 V, with the lowest onset potential of 0.33 V. The obtained results present a new strong non-PGM material for direct methanol electro-oxidation reactions and open new doors for economic and earth-abundant electrocatalysts as an alternative to expensive commercially available catalysts.

Bismuth tungstate nanocomposites for simultaneous detection of hydroquinone and resorcinol

Bi2WO6 nanocomposites were used as effective sensors for detecting environmental pollutants hydroquinone and resorcinol for the first time. Real-time analysis was conducted with water and ointment samples in spiked and unspiked manners.

An Aniline‐Complexed Bismuth Tungstate Nanocomposite Anchored on Carbon Black as an Electrode Material for Supercapacitor Applications

AbstractThe development of efficient electrode materials for supercapacitors has been a topic of extensive research. In this study, a novel electrode material composed of carbon black anchored bismuth‐tungstate‐aniline complex (Bi2(WO4)3/Aniline/CB) (BTACB) nanocomposite was synthesized for supercapacitor applications. The BTACB nanocomposite exhibited excellent electrochemical properties with a specific capacitance of 306 F/g at a current density of 1 A/g and excellent cycling stability. The improved electrochemical performance of the BTACB electrode material is attributed to the synergistic effects of the bismuth‐tungstate and aniline complex, and the conductive carbon black, which provides high surface area and good conductivity. These findings suggest that the carbon black anchored bismuth‐tungstate‐aniline complexed electrode material is a promising candidate for high‐performance supercapacitors.

Synthesis and characterization of quaternary GO/CoCrO3/SiO2/Ag2WO4Nanocomposite based on energy storage and photocatalytic applications

This paper embellished to present novel graphene oxide/cobalt chromium oxide/silicon dioxide/silver tungstate nanocomposite using urea as a reducing agent and tetraethylorthosilicate to enhance stability via hydrothermal approach along with modified hummer’s method, co-precipitation and sol–gel routes. The existence of oxygen, cobalt, chromium, carbon, silicon, silver, and tungsten are confirmed by the nanocomposite elemental composition whereas reduction in particle size up to 4.28 nm indicated by surface morphology. Nanocomposite material had an average crystallite size of 6.85 nm with band gap of 2.5 eV possessing zeta potential value of −16.9 mV. Peak intensity has decreased indicated by Pl spectra whereas FTIR confirms existence of functional groups. The material exhibited excellent electrochemical performance with a specific capacitance of 5124F/g and electrochemical active surface area of 0.02 cm2. The power density ranges from 2881.8 to 2117 W/kg and the energy density ranges from 117.6 to 160.1 Wh/Kg whereas charge transfer resistance value of 1.67 Ω results in electron rate constant 4.98 × 10-9 cms−1. Nanomaterial shows photocatalytic activity about 88.27% degradation efficiency achieved for methylene blue dye under direct sunlight irradiation for 180 min obtaining pseudo kinetics constant value of 1.43x10-2 min−1. Overall results suggest that the GO/CoCrO3/SiO2/Ag2WO4 nanocomposite material has promising potential as energy storage material for supercapacitors and as a photocatalytic material for environmental remediation.

Hydrothermal Synthesis of Bimetallic (Zn, Co) Co-Doped Tungstate Nanocomposite with Direct Z-Scheme for Enhanced Photodegradation of Xylenol Orange

In the present study, pristine ZnWO4, CoWO4, and mixed metal Zn0.5Co0.5WO4 were synthesized through the hydrothermal process using a Teflon-lined autoclave at 180 ℃. The synthesized nanomaterials were characterized by various spectroscopic techniques, such as TEM, FTIR, UV–vis, XRD, and SEM-EDX-mapping to confirm the formation of nanocomposite material. The synthesized materials were explored as photocatalysts for the degradation of xylenol orange (XO) under a visible light source and a comparative study was explored to check the efficiency of the bimetallic co-doped nanocomposite to the pristine metal tungstate NPs. XRD analysis proved that reinforcement of Co2+ in ZnWO4 lattice results in a reduction in interplanar distance from 0.203 nm to 0.185 nm, which is reflected in its crystallite size, which reduced from 32 nm to 24 nm. Contraction in crystallite size reflects on the optical properties as the energy bandgap of ZnWO4 reduced from 3.49 eV to 3.33 eV in Zn0.5Co0.5WO4, which is due to the formation of a Z-scheme for charge transfer and enhancement in photocatalytic efficiency. The experimental results suggested that ZnWO4, CoWO4, and Zn0.5Co0.5WO4 NPs achieved a photocatalytic efficiency of 97.89%, 98.10%, and 98.77% towards XO in 120 min of visible solar light irradiation. The kinetics of photodegradation was best explained by pseudo-first-order kinetics and the values of apparent rate const (kapp) also supported the enhanced photocatalytic efficiency of mixed metal Zn0.5Co0.5WO4 NPs towards XO degradation.

Photocatalytic removal of organic dye using green synthesized zinc oxide coupled cadmium tungstate nanocomposite under natural solar light irradiation

In this work, zinc oxide coupled cadmium tungstate (ZnO-CT) was prepared as a nano-photocatalyst through a green synthesis route using lemon leaf extract and characterized based on diverse microscopic and spectroscopic techniques. To explore the applicabilties of the prepared nanocomposite (NC), its photocatalytic activity has been investigated against Congo red (CR) dye under natural solar light irradiation conditions. ZnO- CT nano-photocatalyst showcases 97% photocatalytic degradation of the CR after 90 min of natural solar light irradiation with quantum yield of 1.16 × 10−8 molecules photon−1. The ZnO-CT NC has shown the enhanced photocatalytic degradation performance against CR when compared to its pristine forms (e.g., ZnO (70%) or CT (44%)). According to the free radical trapping and quenching experiments, the photocatalytic activity of ZnO-CT NC appears to be driven efficiently by superoxide and hydroxyl radicals. The photocatalytic degradation kinetics for CR dye was also studied using the pseudo-first-order, diffusional, and Singh models. The high photocatalytic activity of ZnO-CT NC can be accounted for by the presence of electron-withdrawing functional groups like acids (-COOH) and aldehydes (-CHO) on its surface which helped maintain the prolonged recombination of charge carriers and enhanced stability of ZnO-CT (with moderately low leaching rate of cadmium ions (∼2–5%)).

Enhanced photo-Fenton degradation of Rhodamine B using iodine-doped iron tungstate nanocomposite under sunlight

Enhanced photo-Fenton degradation of Rhodamine B using iodine-doped iron tungstate nanocomposite under sunlight

Corrosion-Resistant Polyaniline-Coated Zinc Tungstate Nanocomposites with Enhanced Electric Properties for Electromagnetic Shielding Applications

Corrosion-Resistant Polyaniline-Coated Zinc Tungstate Nanocomposites with Enhanced Electric Properties for Electromagnetic Shielding Applications

Electro-Oxidation of Metal Oxide-Fabricated Graphitic Carbon Nitride for Hydrogen Production via Water Splitting

Hydrogen is a great sourcez of energy due to having zero emission of carbon-based contents. It is found primarily in water, which is abundant and renewable. For electrochemical splitting of water molecules, it is necessary to use catalytic materials that minimize energy consumption. As a famous carbon material, graphitic carbon nitride, with its excellent physicochemical properties and diversified functionalities, presents great potential in electrocatalytic sensing. In the present work, graphitic carbon nitride-fabricated metal tungstate nanocomposites are synthesized by the hydrothermal method to study their applications in catalysis, electrochemical sensing, and water splitting for hydrogen production. Nanocomposites using different metals, such as cobalt, manganese, strontium, tin, and nickel, were used as a precursor are synthesized via the hydrothermal process. The synthesized materials (g-C3N4/NiWO4, g-C3N4/MnWO4, g-C3N4/CoWO4, g-C3N4/SnWO4, g-C3N4/SrWO4) were characterized using different techniques, such as FTIR and XRD. The presence of a functional groups between the metal and tungstate groups was confirmed by the FTIR spectra. All the nanocomposites show a tungstate peak at 600 cm−1, while the vibrational absorption bands for metals appear in the range of 400–600 cm−1. X-ray diffraction (XRD) shows that the characteristic peaks matched with the JCPDS in the literature, which confirmed the successful formation of all nanocomposites. The electrochemical active surface area is calculated by taking cyclic voltammograms of the potassium–ferrocyanide redox couple. Among the entire series of metal tungstate, the g-C3N4/NiWO4 has a large surface area owing to the high conductive properties towards water oxidation. In order to study the electrocatalytic activity of the as-synthesized materials, electrochemical water splitting is performed by cyclic voltammetry in alkaline medium. All the synthesized materials proved to be efficient catalysts with enhanced conductive properties towards water oxidation. Among the entire series, g-C3N4-NiWO4 is a very efficient electrocatalyst owing to its higher active surface area and conductive activity. The order of electrocatalytic sensing of the different composites is: g-C3N4-NiWO4 > g-C3N4-SrWO4 > g-C3N4-CoWO4 > g-C3N4-SnWO4 > g-C3N4-MnWO4. Studies on electrochemically synthesized electrocatalysts revealed their catalytic activity, indicating their potential as electrode materials for direct hydrogen evolution for power generation.

Fast and simple fabrication of reduced graphene oxide-zinc tungstate nanocomposite with enhanced photoresponse properties as a highly efficient indirect sunlight driven photocatalyst and antibacterial agent

In this study, we reported the fabrication of reduced graphene oxide/ZnWO4(GZW) nanocomposites via a facile coprecipitating method to enhance the electron-hole separation under indirect sunlight irradiation.The physicochemical properties ofdifferent % GZW were characterized by FT-IR, SEM, EDS, and TEM spectroscopy. The incorporation of rGO enhances the degradation efficiency of MB dye under irradiation of visible light (blue LED (λ = 450 nm) and red LED (λ = 610 nm)) for 60 min and the best results were obtained by 10GZW4 which was calcined at 250 °C.Furthermore, the higher photocurrent response intensity and small arc radius of electrochemical impedance (EIS, Nyquist plots) using GZW compared to that of ZnWO4reflected the synergistic effect of GO to enhance the visible light response of ZnWO4. On the other hand, GZW exhibited high antibacterial activity against three bacterial strains and the high activity was obtained using a 10GZW4-250 catalyst.

Sol-Gel Synthesis and Characterization of Highly Selective Poly(N-methyl pyrrole) Stannous(II)Tungstate Nano Composite for Mercury (Hg(II)) Detection

The sol-gel process was used to create a new type of polypyrrole-Stannous(II)tungstate nanocomposite by poly(N-methyl pyrrole (PNMPy) sol in Stannous(II)tungstate gel, produced separately using sodium silicotungstic acid and Tn(II)chloride. Tin(II)tungstate (SnWO3) was made by changing the mixing volume ratios of SnWO3 and with a constant amount of an organic polymer. The composite was characterized by TGA, XRD, FTIR, and SEM measurements. A commercially available glassy carbon electrode (GCE) was modified with PNMPy/nano-Stannous(II)WO3 nanocomposites to create a chemical sensor for selective detection of Hg2+ ions using an effective electrochemical methodology. In the I-V technique, selectively toxic Hg2+ ion was targeted selectively, which shows a rapid reaction toward PNMPy/nano-Stannous(II)WO3/Nafion/GCE sensor. It also demonstrates long-term stability, an ultra-low detection limit, exceptional sensitivity, and excellent reproducibility and repeatability. For 0.1 mM to 1.0 nM aqueous Hg2+ ion solution, a linear calibration plot (r2: 0.9993) was achieved, with a suitable sensitivity value of 2.8241 AM−1 cm−2 and an extraordinarily low detection limit (LOD) of 3.40.1 pM (S/N = 3). As a result, the cationic sensor modified by PNMPy/nano-Stannous(II)WO3/GCE could be a promising electrode.

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.

Effect of Carbon Quantum Dots Doping on Structural, Optical and Antibacterial Properties of Barium Tungstate Nanocomposite Material

Effect of Carbon Quantum Dots Doping on Structural, Optical and Antibacterial Properties of Barium Tungstate Nanocomposite Material

Nickel-zinc tungstate nanocomposites deposited on copper surface for corrosion protection in chloride solution

Several methods such as drop-casting, electrophoretic and chemical vapour depositions have shown the successful deposition of nanomaterials such as graphene oxide, cerium oxide, etc. on metals for various applications such as energy storage, and corrosion protection due to their large surface area and barrier formation. However, these films despite their strong barrier property have been less effective in the area of corrosion protection due to porosity and poor adherence. Here we describe an environmentally benign nickel-zinc tungstate (NiWO4-ZnWO4) nanocomposite with great adhesion and reduced porosity due to improved adsorption sites and film ordering inspired by deoxyribonucleic acid (DNA). The synthesis of the newly designed mixed-metal oxide was done via a simple wet-chemical process in the presence of DNA and in-absence of DNA. Electrochemical analyses confirmed improved corrosion protection of Cu by approximately two orders of magnitude by using nickel-zinc tungstate with DNA compared to only the sample without DNA and the blank system (without any inhibitor).

Synthesis And CharacterizationOf Eu2wo6 By Hydrothermal Method

Metal oxide nanocomposites play an important role in nanoworld. Materials with photo catalytic properties are widely studied because of their numerous applications. These applications include solar cell application and other photodegradation properties too. This photodegradation property include the waste water management too. This paper reports the synthesis and characterization of europium tungstate nanocomposites and explain their photocatalytic applications. The synthesis is carried out with hydrothermal method. XRD, FTIR, SEM and PL studies have been used to study the structural and morphological and optical studies. From these characterizations the sample is studied and further studied for its future uses.

Synthesis of Polyfluorinated Azobenzene Intercalated Tantalum Tungstate Nanocomposite for Determination of Dopamine and Ascorbic Acid

A sandwich-structured C3F7-azo+-TaWO6 nanocomposite used as an electrochemical sensor for simultaneous determination of dopamine (DA) and ascorbic acid (AA) was synthesized by guest-guest exchange method. n-PrNH3 +-TaWO6 precursor was ion-exchanged with cationic polyfluorinated azo dye, trans-[2-(2,2,3,3,4,4,4-heptafluorobutylamino)ethyl]-{2-[4-(4-hexyphenylazo)-phenoxy]ethyl} dimethylammonium bromide (abbreviated as C3F7-azo+Br−). The structure and morphology were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer analysis (EDS) and Fourier transform infrared spectrometer (FTIR). Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were used to test the electrochemical properties of C3F7-azo+-TaWO6 nanocomposite. The experimental results show that C3F7-azo+-TaWO6/GCE can detect AA and DA at the same time, with the potential difference reaching 356 mV. Moreover, electrochemical sensing toward DA and AA on C3F7-azo+-TaWO6/ GCE exhibits low detection limits of 0.81 μM and 1.6 μM, respectively, each in a linear range of 0.05 to 0.31 mM.

Polythiophene/graphene/zinc tungstate nanocomposite: Synthesis, characterization, DC electrical conductivity and cigarette smoke sensing application

Herein, we are reporting the synthesis and characterization of polythiophene (PTh) and its novel nanocomposites with zinc tungstate (ZT) and graphene/zinc tungstate (G/ZT) hybrid for Direct current (DC) electrical conductivity based cigarette smoke sensing at room temperature. X-ray diffraction, Fourier-transform infrared, Raman, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy and thermogravimetric analysis techniques were used for the characterization of the as-prepared materials. The results showed that the DC electrical conductivity and sensing performance of PTh significantly improved by incorporation of ZT and G/ZT into it. PTh/G/ZT-3 (i.e. PTh/G/ZT nanocomposite containing 15 wt% G/ZT) was found to be the best sensor in terms of sensing response (81.5%) and reversibility (90.55%) along with the most stable semiconductor under isothermal and cyclic ageing conditions. Sensing response of PTh/G/ZT-3 was also tested in the exposure to various components of cigarette smoke (namely ammonia, carbon dioxide, ethanol, formaldehyde, acetone, benzene, toluene, phenol) and the highest sensing response was observed in the exposure to ammonia. The significant increase in conductivity of PTh/G/ZT nanocomposites was explained by the transfer of polarons from PTh to graphene, that is, creation of a hole in graphene where they achieved rapid mobility along with the extended π-conjugated system. Finally, a sensing mechanism was proposed through adsorption–desorption of cigarette smoke on the surface of PTh/G/ZT where electronic interactions between polarons of PTh and various components of cigarette smoke (mainly ammonia and ethanol) affected the change in DC electrical conductivity.

Construction of novel biochar supported copper tungstate nanocomposites: A fruitful divergent catalyst for photocatalysis and electrocatalysis

In the past few years, the occurrence of pharmaceutical wastes into the environment increases in day-to-day and poses negative risks to the living organisms. In this work, we developed novel biochar supported copper tungstate nanocomposites (Bio-CuWO4 NCs) and utilized as a visible light active photocatalyst for the degradation of ciprofloxacin (CF) drug and electrocatalyst for the oxidation of methanol. The Bio-CuWO4 NCs were synthesized by simple hydrothermal method and the successful formation was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The Brunauer-Emmett-Teller (BET) measurements revealed that the Bio-CuWO4 NCs exhibited higher active surface area when compared to pristine biochar. The UV–visible spectroscopy results portrayed that the Bio-CuWO4 NCs degrade up to 97% of CF aqueous suspension after 90 min of visible light irradiation with good repeatability and stability. In addition, the Bio-CuWO4 NCs demonstrated higher peak current in methanol oxidation reaction.

Organic solar cells of enhanced efficiency and stability using zinc oxide:zinc tungstate nanocomposite as electron extraction layer

Abstract In this work, the enhanced performance of inverted bulk heterojunction (BHJ) organic solar cells (OSCs) using zinc oxide (ZnO):polyoxometalate (POM), in particular sodium metatungstate (Na6H2W12O40), nanocomposite films as electron extraction layers (EELs) is demonstrated. The addition in the precursor solution of ZnO of sodium metatungstate results in the formation of ZnO:ZnWO4 nanocomposite as evidenced by X-ray diffraction, Fourier transform infrared and photoluminescence measurements. The formation of ZnO:ZnWO4 heterointerface reduces the work function of the nanocomposite material leading to a more favorable electron extraction/transport at the organic blend/electron transport layer interface. Additionaly, the amount of zinc interstitial defects is suppressed having a profound positive effect on device stability. As a result, simultaneously improved open-circuit voltage (Voc), short-circuit current density (Jsc) and fill factor (FF) are obtained in the devices using the ZnO :ZnWO 4 nanocomposites. Therefore, both of the inverted BHJ OSCs composed of either poly (3-hexylthiophene) (P3HT):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) or P3HT:indene-C60 bisadduct (IC60BA) photoactive blends show a significant performance enhancement when using the nanocomposite electron extraction layer, exhibiting a 27% and 23%, respectively, improvement in their power conversion efficiency (PCE) values compared to the reference devices based on pristine ZnO. In addition, the devices with the ZnO :ZnWO 4 layer exhibit a remarkable stability enhancement retaining 95% of their initial PCE value upon storage for 500 h.