CoWO4 Nanoparticles Research Articles

Synergistic photocatalytic degradation of TC-HCl by MIL-53(Fe)/CoWO4 composite and PMS under visible light

A series of novel MIL-53(Fe)/CoWO4 composites were synthesized by combining MIL-53(Fe) and CoWO4 nanoparticles via solvothermal method. The structural characterizations showed that CoWO4 nanoparticles were uniformly distributed on the surface of hexagonal bipyramid MIL-53(Fe). Combining XPS and Mott-Schottky plots, a Z-scheme heterojunction was formed between MIL-53(Fe) and CoWO4, resulting in a significant improvement in the electron-hole pair separation efficiency. UV–vis diffused reflectance spectra indicated that the optical arrange of MIL-53(Fe)/CoWO4 composites were expanded to visible light. The photocatalytic degradation experiments under visible light irradiation showed that MIL/CWO-60 synergistically with PMS degraded 90.5 % of TC-HCl within 50 min. The XRD spectra of used and unused composites were identical, indicating good stability in four consecutive cycles. Electron paramagnetic resonance (EPR) and free radicals trapping experiment revealed that active species included O2−, SO4−, h+, OH and 1O2, and mechanism of the synergistic degradation of TC-HCl by MIL-53(Fe)/CoWO4 composites and PMS was proposed.

Unveiling the Effect of Solution Concentration on the Optical and Supercapacitive Performance of CoWO4 Nanoparticles Prepared via the Solvothermal Method

Unveiling the Effect of Solution Concentration on the Optical and Supercapacitive Performance of CoWO4 Nanoparticles Prepared via the Solvothermal Method

Reinforced photogenerated electron convergence on graphdiyne(g-CnH2n-2) “as an active site and substrate” for enhance photocatalytic hydrogen production

Graphdiyne(GDY), as a carbon-based catalyst with tunable electronic structure, has a significant impact on the advancement of sustainable photocatalytic technology. Its tunable electronic structure can effectively regulate the activity and selectivity of photocatalytic reaction. In this paper, GDY was prepared by a new method of ball milling HEB-TMS, and CoWO4 nanoparticles were uniformly loaded on the surface of GDY to construct a Type-II heterojunction. GDY provides a dispersed and effective substrate for CoWO4, forming a closer contact interface. Based on GDY's unique electronic structure and the formation of Type-II heterojunction, GDY/CoWO4 enhances the separation of photoexcited electrons and holes, thus increasing the electron cloud density on GDY. As an electron acceptor and active site for hydrogen production, GDY promotes the proton reduction reaction. In addition, the charge transfer process of GDY/CW-15 was demonstrated by in-situ XPS and UPS, and the corresponding hydrogen production mechanism was proposed. This study provides a facile and efficient method for preparing GDY and a new idea for heterojunction photocatalyst based on GDY substrate.

S-scheme heterojunction constructed by ZnCdS and CoWO4 nano-ions promotes photocatalytic hydrogen production

Low-cost and efficient photocatalyst is an important aspect of photocatalytic hydrogen production. In this study, a highly efficient and stable composite photocatalyst was synthesized by assembling ZnCdS nanoparticles and CoWO4 nanoparticles. Under the 5 W LED lamp, the hydrogen production of the composite catalyst ZCS/CW-10 is as high as 839.85 μmol in five hours, which is 5.2 times that of the pure ZnCdS photocatalyst, respectively. After four cycles, the hydrogen production still reaches 640.37 μmol, which is 76.3% of the initial activity. This is because the introduction of CoWO4 increases the absorption of visible light by ZnCdS, and effective interface contact with each other between nanoparticles can effectively accelerate the transfer of photo generated charges between semiconductors, increase the active sites of surface hydrogen production, and achieve efficient H2 production. The staggered band structure makes ZnCdS and CoWO4 follow the electron flow scheme of S-scheme heterojunction, which is proved by in-situ XPS. The S-scheme heterostructure of ZCS/CW retains high redox potential and prolongate the lifetime of electron-generated carriers, making it more conducive to proton reduction to produce H2. This work provides a novel and convenient way to construct an efficient S-scheme heterojunction scheme, which is helpful for the rapid and effective production of metal sulfide-based photocatalysts and the rapid construction of photocatalytic water splitting hydrogen production systems. It has important research value in the utilization of new energy hydrogen energy and environmental protection.

Synthesis of CoWO4/g-C3N4 Z-scheme heterojunction for the efficient photodegradation of diazinon with the addition of H2O2

Pesticides are on the list of substances that are routinely monitored by agencies and organizations in various natural environments and habitats. Diazinon (DZN) is the active ingredient in more than 20 agricultural pesticides, it causes the most damage and has been prohibited in many countries around the world. The final product CoWO4/g-C3N4 Z-scheme heterojunction was successfully synthesized in this work, where CoWO4 nanoparticles were deposited on the surface of g-C3N4. CoWO4/g-C3N4 structure allowed for the efficient separation of photo-generated electron-hole pairs, with electrons at the CoWO4 CB migrating to the g-C3N4 VB and preserving the electrons at the g-C3N4 CB and holes in the CoWO4 VB. The photodegradation efficiency of DZN using CoWO4/g-C3N4 Z-scheme heterojunction was investigated, as compared with its precursors, such as CoWO4, and g-C3N4. CoWO4/g-C3N4 Z-scheme heterojunction demonstrated the highest degradation capacity for DZN removal. Based on the results, the photocatalysis of the CoWO4/g-C3N4 Z-scheme heterojunction can be recycled for the effective removal of DZN by simple washing after three runs, proving the heterojunction’s stability and suggesting CoWO4 as a promising material for the removal of DZN from contaminated water sources.

Synthesis and electrochemical performance of CoWO4 and CoWO4/MWCNT nanocomposites for highly efficient supercapacitor applications

Electrochemical supercapacitor is valid and as an innovative type of energy storage device in the recent years. In this study, we successfully produced the CoWO4 nanoparticles and CoWO4/MWCNT nanocomposites using a straightforward hydrothermal method and an annealing procedure. The created nanocomposites are evaluated using high-resolution field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Additionally, the electrical conductivity is determined using electrochemical impedance spectroscopy (EIS) further, the specific capacitance is determined using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. Higher electrochemical behavior is exhibited by the CoWO4/MWCNT composite electrode, delivers the capacitance of 543 F/g at 5 mV/ s. The CoWO4/MWCNT composite electrode demonstrates the exceptional 93 % cycle stability and 98 % coloumbic efficiency, showing better ion storage behavior in their huge electroactive areas. A possible source of electrode materials for supercapacitor applications has been found in this CoWO4/MWCNT composite due to its charge-storing capabilities.

Hydrothermal synthesis of CoWO4 nanoparticles and evaluation of their supercapacitive performance

The present report employed the hydrothermal method to synthesize the cobalt tungstate (CoWO4) nanoparticles (NPs). The Rietveld refinement, Raman, XPS and FTIR spectroscopy study suggest the pure phase formation of the wolframite-type monoclinic crystal structure of CoWO4 NPs. Surface morphological images reveal uniform nanostructured flower-like morphology. The cyclic voltammogram reveals that the CoWO4-based electrode material shows a specific capacitance (Csp) of 571 F/g, while GCD exhibits a specific capacitance (Csp) of 712 F/g. The electrode material possesses an internal resistance of 0.92 Ω. The coulombic efficiency of the CWO-based electrode is 95.50 %. Furthermore, a capacity retention of 84.2 % was retained over 5000 charge-discharge cycles.

Synthesis and Characterization of Z-Scheme Heterojunction CoWO4/RGO/g-C3N4 as a Visible Light-Driven Photocatalyst for Novel Removal of Organic Pollutant

In this study, novel Z-scheme heterojunction photocatalyst CoWO4/RGO/g-C3N4 was successfully fabricated by a facial hydrothermal. Obtained morphology and topography studies indicated that deposition of reduced graphene oxide (RGO) and CoWO4 nanoparticles did not affect the structure of g-C3N4 sheets. However, optical results showed that visible light absorption of the material was significantly improved. The synthesized heterojunction photocatalyst exhibited improved photocatalytic performance in the novel degradation of rhodamine B, even upon visible irradiation. The improved photocatalytic performance was ascribed to interfacial contact between g-C3N4 and CoWO4 in a Z-scheme heterojunction in which RGO served as electron mediator accelerating its transfer between g-C3N4 and CoWO4 to minimize recombination of photogenerated electron-hole pairs. Therefore, rhodamine B degradation by CoWO4/RGO/g-C3N4 was 1.87 times higher than pristine g-C3N4. The synthesized heterojunction was relatively stable with no distinct reduction in photocatalytic activity after three recycling runs. The fabrication of heterojunction CoWO4/RGO/g-C3N4 is an efficient strategy to develop high-performance photocatalysts for various photocatalytic applications.

Asymmetrical zinc phthalocyanine conjugated to various nanomaterials for applications in phototransformation of organic pollutants and photoinactivation of bacteria

Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.

Facile design of wolframite type CoWO4 nanoparticles: A selective and simultaneous electrochemical detection of quercetin and rutin

Facile construction of CWO/SPCE for electrochemical detection of QCT and RU. • Wolframite type CoWO 4 was synthesized by the facile one-step coprecipitation method. • CoWO 4 /SPCE showed improved performance for simultaneous detection of QCT and RU. • The proposed sensor demonstrated low LOD, high selectivity, and good stability. • Real-time analyses of QCT and RU was investigated in fruit juice sample. Flavonoids (FLs) have impressive attention in food-related items and medicinal areas because of their significant impact on the quality, function, and safety of the products. Thus, it is crucial to develop a simple and fast detection method for FLs in food and pharmaceutical samples. Consequently, we chose the rapid and cost-effective electrochemical detection method for FLs in a food sample. Herein, we report the facile design of wolframite type CoWO 4 (CWO) as an efficient electrocatalyst for simultaneous detection of quercetin (QCT) and rutin (RU). Crystallinity, structural morphology, and electrochemical investigations of CWO were characterized by using various spectrometric techniques and electroanalytical methods. The CWO modified screen-printed carbon electrode (SPCE), compared with a bare electrode demonstrated high electrochemically active surface area, better conductivity, and improved electrochemical sensing performance toward QCT and RU. Considering these advantages of CWO/SPCE, the optimized differential pulse voltammetric results showed the lowest detection limit of QCT as 0.022 µM and RU as 0.018 µM with the linear concentration of 0.2–521 µM (QCT) and 0.2–681 µM (RU). Significantly, CWO/SPCE displayed excellent selectivity for QCT and RU with effective interfering molecules, good stability (cyclic and storage), and reproducibility with five successive measurements. The practical analysis test was applied to QCT and RU in real fruit juice with the observed recoveries being acceptable.

Biomass-derived carbon (BC) modified CoWO4 nanoparticles composites for improved performance of dye-sensitized solar cells

Semiconductor-based photoanodes have sparked a lot more interest in the energy and environmental fields. A hydrothermal method was used to construct cobalt tungstate (CoWO4)/bio carbon (BC) nanocomposites. PXRD, SEM, UV–Vis DRS, and PL analyses are used to properly characterise the structural, morphological, and autoelectric properties of the synthesized samples. Because of the synergistic contact between CoWO4 and BC, this effective excition separation leads to increased photovoltaic activity. According to the XRD and TEM results, wolframite monoclinic structure with nanosized individual particles in the range of 30–40 nm was homogeneously adorned on the surface of BC nanosheets. By using dye-sensitized solar cells (DSSCs) as working electrodes, the photovoltaic properties of the cells were studied. The CoWO4/BC photoanode developed demonstrated high power conversion efficiency (7.01%), IPCE (73.21%), and long-term stability. In addition, the CoWO4/BC photoanode demonstrated high electrocatalytic activity, low resistance, and a high charge carrier process. The enhanced methodology was also thoroughly described.

Zeolitic imidazolate framework grafted by cobalt tungstate as an efficient photocatalyst for photocatalytic oxidative desulfurization of dibenzothiophene

In this research, novel nanohybrid of zeolitic imidazolate framework supported cobalt tungstate semiconductor (ZIF-67@CoWO4) with various CoWO4 loading ratios (from 0 to 30 %wt) has been fabricated as a visible-light-driven photocatalyst for dibenzothiophene (DBT) removal from model fuel. XRD, UV-DRS, FE-SEM, EDX, BET and VSM characterizations were used to analyze the fabricated nanocomposites. At specific experimental conditions (100 mg/l DBT in model fuel, photocatalyst dosage of 2 g/l, visible light irradiation time of 2 h and H2O2/DBT mole ratio of 8:1), the ZIF-67@(1 wt%)CoWO4 sample exhibited excellent photocatalytic oxidative desulfurization (PODS) activity (96.7%) between different prepared photocatalysts, The improved reaction performance of ZIF-67@(1%wt)CoWO4 heterostructure can be attributed to the reciprocal effects of the high adsorption capacity of ZIF-67, optical properties of CoWO4 nanoparticles and the high charges separation and transfer efficiencies. Besides, the ZIF-67@CoWO4 photocatalyst possesses good stability for PODS and can be reused for five reaction cycles without a significant activity loss, indicating that it might be very useful in the deep PODS of hydrocarbon fuel.

Hydrothermal design of CoMoO4@CoWO4 core-shell heterostructure for flexible all-solid-state asymmetric supercapacitors

As electrode material, cobalt-molybdenum oxide (CoMoO4) attracts more attention for energy storage device through its various oxidation states and good electrochemical properties. However, its low conductivity and energy density still hinder its applicability. To integrate its practicability as advanced electrode material in supercapacitor, we chose CoWO4 as conductive shell material to boost the conductivity on the core surface. Herein, a kind of novel CoMoO4@CoWO4 nanorods core-shell heterostructure is designed with two-step hydrothermal strategy. The CoMoO4 nanorods fully covered by CoWO4 nanoparticles provides ultrahigh specific surface area of 331.1 m2·g−1. Benefiting from synergistic effect, CoMoO4@CoWO4 electrode results superb specific capacitance of 2070 F·g−1 at 0.5 A·g−1 and marvelous stability behavior of 92% after 10,000 cycles. The charge storage mechanism is dominated by the capacitive contribution. Meaningfully, at 0.5 Aˑg−1, all-solid-state asymmetric CoMoO4@CoWO4//activate carbon supercapcitor device delivers ultrahigh specific energy of 71.8 Wh·kg−1 at 354 W·kg−1 specific power. Interestingly, two asymmetric devices can illuminate red and green LEDs.

The effect of nitrogen-doped carbon nano-onions on the third order nonlinear optical responses of CoWO4-MnO2 nanocomposites

CoWO4, CoWO4-MnO2, and CoWO4-MnO2-NCNO nanostructures were prepared via precipitation method followed by calcination at 450 °C. The nitrogen-doped carbon nano-onions (NCNOs) were synthesized by annealing the ultra-dispersed aminated-nanodiamond solution under He gas at 1150 °C followed by calcination at 400 °C. The morphological, structural, and optoelectronic responses of the samples were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Z-scan methods. The order of the nonlinear absorption (NLA) and nonlinear refraction (NLR) of samples are 10−3 (cm/W) and 10−8 (cm2/W), respectively. In different incident intensity of laser, all synthesized samples showed positive and negative sign of NLA and NLR indices, respectively. The NLA coefficient originates from two photon absorption effect and NLR indices indicate the self-defocusing effect. The lowest nonlinear optical response belonged to CoWO4 nanoparticles. CoWO4-MnO2-NCNO nanocomposite showed the higher nonlinear optical responses than CoWO4 and CoWO4-MnO2 nanocomposites. The large ratio of the surface area of NCNO and oxygen reduction activity of NCNO due to high incident intensity are the main reasons for increasing nonlinearity. The nonlinearity results are promising candidate for using in optical and photonic devices.

Fabrication and photocatalytic degradation activity of core/shell ZIF-67@CoWO4@CoS heterostructure photocatalysts under visible light

In this work, high photocatalytic degradation activity towered organic pollutants (methylene blue (MB) dye) has been achieved under visible light using new core/shell ZIF-67@CoWO4@CoS heterostructures. The optical, structural and morphological properties were studied using XRD, FE-SEM, EDX, UV-DRS, VSM, and BET surface area characterization methods. Noticeably, the photocatalytic degradation efficiency of the ZIF-67@CoWO4@CoS photocatalyst was higher to that of its individual-component complements (about 100% after 10 min of irradiation time). Furthermore, ZIF-67@CoWO4@CoS photocatalyst showed higher activity than ZIF-67@CoWO4 and ZIF-67@CoS nanocomposites. This enhanced photocatalytic degradation efficiency of ZIF-67@CoWO4@CoS can be attributed to the synergistic effects of ZIF-67, CoWO4 and CoS nanoparticles, and the narrow band gap energy of the synthesized core/shell ZIF-67@CoWO4@CoS heterostructure. The photocatalytic degradation of MB followed a pseudo-first-order kinetic model (K1 = 0.105 min−1). Moreover, the recyclability study exhibited that the ZIF-67@CoWO4@CoS photocatalyst was extremely stable and can be used eight times without considerable loss in its photocatalytic degradation activity. The results of this work underline the use of effective, low-cost and easily available ZIF-67@CoWO4@CoS photocatalyst for the decomposition of wide range of organic pollutants in wastewater under visible light irradiation.

Preparation of Cobalt tungstate nanomaterials and study on sonocatalytic degradation of Safranin t

Cobalt tungstate (CoWO4) nanoparticles were prepared by method of hydrothermal synthesis and regulated via adding different doses of surfactant sodium dodecyl sulfate (SDS). Then, degradation of dye Safranin T (ST) under the ultrasound irradiation utilizing CoWO4 nanoparticles as sonocatalysts was investigated. Through a series of experiments such as ultrasonic degradation methods, the following results were got: Firstly, CoWO4 nanoparticles with different dosage of SDS had good sonocatalytic performance in decomposition of ST. And the degradation rate of ST reached the optimum value of 85.9% under the conditions of CoWO4 with dosage of 0.5 g SDS (CoWO4-0.5), 1.0 g/L CoWO4-0.5, 15 mg/L initial dye concentration and 160 W ultrasonic power in 120 min, followed by the TOC removal rate of 74.57%. Secondly, there was a significant synergistic effect between COWO4-0.5 and ultrasonic (synergy index value was 3.75 for US + COWO4-0.5). Thirdly, the degradation of ST is mainly attributed to the generating of hydroxyl radicals and other reactive oxygen species. And the catalyst decomposes nitrogen atom in the ST molecule to produce NO3– ion. Lastly, CoWO4-0.5 exhibited good stability and reusability in the process of sonocatalytic decomposition after four cycles. With these results, a new research reference might be provided for degradation of organic pollutants.

Construction of p-n heterojunctions by modifying MOF-derived α-Fe2O3 with partially covered cobalt tungstate for high-performance ethyl acetate detection

Metal organic framework (MOF)-derived porous metal oxide nanostructures have become a kind of promising material for gas-sensitive detection. A facile solvothermal method was adopted to construct CoWO4/α-Fe2O3 nanocomposites, in which MIL-53(Fe) was used as the precursor of α-Fe2O3. The prepared α-Fe2O3 has a unique three-dimensional nanostructure, resulting in good dispersion of CoWO4 nanoparticles on the surface and a distinct structure of partially CoWO4-modified α-Fe2O3 (PC-Fe2O3). XPS characterization indicates that this PC-Fe2O3 heterostructure exposes the high density of active centers, leading to an increase in the amount of adsorbed oxygen on the material surface. The sensor based on the prepared CoWO4/α-Fe2O3 composite exhibits higher response, faster response/recovery, and better selectivity to ethyl acetate than the pristine α-Fe2O3 octahedra. It is believed that the enhanced sensing performance can be attributed to the resistance modulation effect of the heterojunction, the properties of MOFs-derived material, and the formation of the unique PC-Fe2O3 structure.

Toxicity evaluation and preparation of CoWO4 nanoparticles towards microalga Dunaliella salina.

The increasing use of nanoparticles and their many applications increases the likelihood of their presence in the environment. This possibility of presence necessitates the study of the effect of these substances on aquatic species. In this research, CoWO4 nanoparticles were synthesized by the ultrasonic method. Various conditions in the synthesis process were investigated to obtain the appropriate size of the nanoparticles. After selecting the optimum particles, these nanoparticles were used to investigate their effect on the growth of Dunaliella salina. For this purpose, the algal cells were subjected to three different concentrations of nanoparticles (15, 30, and 60 mg/L). The study results on algae growth parameters showed that these parameters depend on the value of nanoparticles. At 15 and 30 mg/L concentrations of the nanoparticles, numbers of cells, specific growth, biomass, and pigments showed a significant boost compared to the mentioned parameters of the control treatment. Measurement of malondialdehyde (MDA) showed that this parameter was directly related to the increase in the concentration of nanoparticles. At 60 mg/L of the nanoparticles, the MDA level was higher than the control and other treatments. This increase reflects the destructive effect of the nanoparticles on algal cells. Finally, the results showed that algae could be useful for studying the environmental effects of nanoparticles and their safety.

Mn0.2Cd0.8S nanorods assembled with 0D CoWO4 nanoparticles formed p-n heterojunction for efficient photocatalytic hydrogen evolution

In this work, p-type semiconductor CoWO4 nanoparticles was successfully anchored on the surface of n-type Mn0.2Cd0.8S nanorods, and p-n type heterostructure photocatalysts with low cost and high efficiency were synthesized. By optimizing the loading of CoWO4 nanoparticles, the hydrogen evolution rate of the compound can reach a maximum, the peak is 408 μmol/5 h. Under visible light irradiation, it is equivalent to 3.61 times pure Mn0.2Cd0.8S. In addition, the composite catalyst has favorable durability and structural stability. In terms of morphology, the combination of nanorods (SBET = 24 m2g-1) and nanoparticles (SBET = 12 m2g-1) increased the specific surface area of the composite catalyst (SBET = 31 m2g-1), thus the composite exposed more active sites. In terms of heterojunction, the conduction bands of two semiconductors were determined by UV–vis diffuse reflection and Mott-Schottky, and the construction of p-n heterojunction was verified. The results of photochemical experiment further indicate that the built-in electric field in the p-n type heterostructure not only accelerates the electron-hole pair transfer, but vastly enhances the carrier average lifetime. In this paper, the morphology of the photocatalyst was modified and p-n heterojunction was constructed. The result is that the performance of Mn0.2Cd0.8S MCS was improved and the possible mechanism of photocatalytic hydrogen evolution was proposed.

CTAB assisted sol-gel synthesis and characterization of FeWO4 and CoWO4 nanoparticles

Designing sol-gel synthesis of stable oxide nanostructures are one among the few key steps in simplifying the synthesis strategies for mass scale production of such nanomaterials. Herein, low temperature, CTAB based sol-gel technique has been adopted for the development of iron and cobalt tungstate nanostructures as they are one among the potential oxide nanostructures. As synthesized nanoparticles possess fine particle size in polycrystalline nature with good thermal stability and magnetic properties. The procedure adopted produced near-pure materials with no noticeable binary oxide formation and other impurities. These results may lead to promising applications