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1.
NiFe2O4 nanoparticles are modified by graphene quantum dots (GQDs) and utilized to stabilize the Cu(II) nanoparticles as a novel magnetically retrievable catalytic system (Cu(II)/GQDs/NiFe2O4) for green formation of 4H‐pyrimido[2,1‐b]benzothiazoles. The prepared catalyst can be isolated assisted by an outer magnet and recovered for five courses without significant reduction in its efficiency. The as‐prepared magnetic heterogeneous nanocomposite was characterized by UV–Vis, FT‐IR, XRD, EDS, VSM, TEM, and ICP. Performing the reactions in environmentally friendly and affordable conditions (water), the low catalyst percentage, high yield of products, short reaction times, and easy workup are the merits of this protocol.  相似文献   

2.
In order to make a microwave absorbent material with good dielectric and magnetic properties, well dispersed microwave absorbing hybrid epoxy polymer composites containing nickel doped Fe3O4 nanocrystals coated on carbon nanotubes (NiFe2O4‐MWCNTs/epoxy) were synthesized by the combined precipitation‐hydrothermal method in 1‐30 wt.% of nanoparticles. Nickel possess well interaction with microwave radiation and represents fine electromagnetic interference (EMI) shielding and by dopping it into ferrite spinel structures, does not show any tendency to oxidation. Well‐dispersed NiFe2O4–MWCNTs/epoxy nanocomposite prepared by new in‐situ polymerization method. First, NiFe2O4–MWCNT nanoparticles ultrasonicated in acetone and after mixing with epoxy resin ultrasonicated again. Finally, hardner added to the composite and tuned temperature for evaporating solvent. X‐ray diffraction (XRD) and energy dispersive spectroscopy (EDS) confirmed the synthesizing NiFe2O4 nanoparticles. Saturation magnetization value of NiFe2O4‐MWCNTs is about 29 emu/g with very low remanence and coercivity content, which revealed that the NiFe2O4‐MWCNTs is ferromagnetic nanocrystal. Transmission electron microscopy (TEM) used to characterize the distribution of NiFe2O4 nanocrystals on the surface of MWCNTs. The TEM images show that NiFe2O4 nanocrystals have a mean size of 12 nm, and completely coated on the exterior surface of MWCNTs. The obtained results of reflection loss revealed that the maximum values of reflection loss of the NiFe2O4‐MWCNTs/epoxy increase by enhancing the content of nanoparticles until 10 wt.% and decreases in 30 wt.%.  相似文献   

3.
The magnetic CuFe2O4 nanoparticles have been synthesized and characterized by various spectroscopic methods, including X‐ray diffraction (XRD), O K, Cu and Fe K ‐edge X‐ray absorption near edge structure (XANES), energy dispersive X‐ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The azide‐alkyne cycloaddition by the reaction of various phenylacetylenes with a mixture of benzyl halides and NaN3 and also three component (A3) coupling reaction of aldehyde, alkyne and amine catalyzed by CuFe2O4 nanoparticles under aerobic conditions led to the formation of the 1,4‐disubstituted‐1,2,3‐triazoles and propargylamines in excellent yields. The catalyst can be recovered by applying an external magnetic field for the subsequent cycloaddition reactions and reused without any tangible loss in catalytic efficiency.  相似文献   

4.
A magnetic photocatalyst TiO2/NiFe2O4 (TN) with typical ferromagnetic hysteresis was prepared by a sol‐gel method, which is easy to be separated from a slurry‐type photoreactor under the application of an external magnetic field, being one of promising photocatalysts for wastewater treatment. The analysis of XRD indicated that the highly dispersed NiFe2O4 nanoparticles prevented the formation of rutile phase to some extent. A transmission electron microscope (TEM) was used to characterize the structure of the photocatalyst, indicating that the NiFe2O4 nanoparticles highly dispersed among TiO2 nanoparticles. The prepared photocatalyst showed high photocatalytic activity for the degradation of methyl orange in water. The degradation results revealed that the NiFe2O4 nanoparticles played the role of recombination centre of photogenerated electrons and holes for the TN photocatalyst, which gave rise to the decrease in photocatalytic activity. Moreover, the experiment on recycled use of TN demonstrated a good repeatability of the photocatalytic activity.  相似文献   

5.
Targeted drug delivery is a promising approach to overcome the limitations of classical chemotherapy. In this respect, Imatinib‐loaded chitosan‐modified magnetic nanoparticles were prepared as a pH sensitive system for targeted delivery of drug to tumor sites by applying a magnetic field. The proposed magnetic nanoparticles were prepared through modification of magnetic Fe3O4 nanoparticles with chitosan and Imatinib. The structural, morphological and physicochemical properties of the synthesized nanoparticles were determined by different analytical techniques including energy‐dispersive X‐ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), Fourier‐transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HR‐TEM), vibrating sample magnetometry (VSM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). UV/visible spectrophotometry was used to measure the Imatinib contents. Thermal stability of the prepared particles was investigated and their efficiency of drug loading and release profile were evaluated. The results demonstrated that Fe3O4@CS acts as a pH responsive nanocarrier in releasing the loaded Imatinib molecules. Furthermore, the Fe3O4@CS/Imatinib nanoparticles displayed cytotoxic effect against MCF‐7 breast cancer cells. Results of this study can provide new insights in the development of pH responsive targeted drug delivery systems to overcome the side effects of conventional chemotherapy.  相似文献   

6.
Sulfamic acid immobilized on diethylenetriamine functionalized Fe3O4 nanoparticles (SA‐DETA‐Fe3O4) was successfully prepared and characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), vibrating sample magnetometer (VSM), thermo gravimetric analysis (TGA), X‐Ray diffraction (XRD) and scanning electron microscopy (SEM). The sulfamic acid was found as a magnetically separable and highly active catalyst for the oxidative coupling thiols, oxidation of sulfides. Furthermore, the SA‐DETA‐Fe3O4 showed the high catalytic activity in Knoevenagel condensation of aromatic aldehydes with active methylene compounds (malononitrile and ethyl cynoacetate). The nanosolid catalyst could be easily recovered by a simple magnetic separation and reused for many cycles without deterioration in catalytic activity.  相似文献   

7.
A magnetically separable NiFe2O4@GO–Pd composite (GO = graphene oxide) was successfully prepared by a facile one‐pot hydrothermal strategy. This new kind of hybrid material was fully characterized using powder X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy and vibrating sample magnetometry. Structural characterizations confirmed the formation of NiFe2O4 and Pd nanocrystals, and the close anchoring between nanoparticles and GO sheets. Additionally, the as‐prepared NiFe2O4@GO–Pd nanocomposite was effectively employed in the palladium‐catalyzed Heck reaction in an ethanol–water system as a green solvent. The catalyst was completely recoverable with the simple application of an external magnetic field and with no obvious loss of catalytic activity even after six repeated cycles. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

8.
In this article, we present a simple and efficient method to synthesize a magnetic NiFe2O4 nanocatalyst under hydrothermal conditions. Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X‐ray spectroscopy (EDX) analyses confirmed the synthesis of NiFe2O4 nanoparticles. These nanoparticles showed satisfactory catalytic activity for determination of norepinephrine (NE) in the presence of folic acid (FA) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Differential pulse voltammetry peak currents of NE increased linearly with their concentrations in the range of 1.0 × 10?7–5.0 × 10?4 M, and the detection limit for NE was 2.3 × 10?8 M, respectively. The modified electrode displayed strong function for resolving the overlapping voltammetric responses of NE and FA into two well‐defined voltammetric peaks. In the mixture containing NE and FA, the two compounds can well separate from each other with a potential difference of 510 mV between NE and FA, which was large enough to determine NE and FA individually and simultaneously. Additionally, the prepared electrochemical sensor demonstrated a practical feasibility for real sample determination.  相似文献   

9.
The carbon–carbon cross coupling reactions through transition‐metal‐catalyzed processes has been significantly developed for their important synthetic applications. In this research, we have shown that NiFe2O4@TASDA‐Pd(0) is a highly active, novel and reusable catalyst with excellent performance for the Mizoroki–Heck coupling reaction of several types of iodo, bromo, and even aryl chlorides in DMF under ultrasound irradiation. The novel palladium catalyst prepared and characterized by using FT‐IR spectrum, X‐ray diffraction (XRD), scanning electron microscopy (SEM), Energy‐dispersive X‐ray spectroscopy (EDX), thermo gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The catalyst can be recovered and recycled several times without marked loss of activity.  相似文献   

10.
A highly porous metal‐organic framework, MIL‐101(Fe), was prepared by a solvothermal method in the presence of amino‐modified Fe3O4@SiO2 nanoparticles, in order to achieve Fe3O4/MIL‐101(Fe) nanocomposite, which was characterized by XRD, FT‐IR, SEM, TEM, BET, and VSM. This hybrid magnetic nanocomposite was employed as heterogeneous catalyst for α‐amino nitriles synthesis through three‐component condensation reaction of aldehydes (ketones), amines, and trimethylsilyl cyanide in EtOH, at room temperature. The recoverability and reusability was admitted for the heterogeneous magnetic catalyst; no significant reduction of catalytic activity was observed even after five consecutive reaction cycles.  相似文献   

11.
In the present study, Fe3O4 nanoparticles were prepared via simple and versatile procedure. Then, a novel and green catalyst was synthesized by the immobilization of Ni on Fe3O4 nanoparticles coated with adenine. The activity of this nanostructure compound was examined for the oxidation of sulfides, oxidative coupling of thiols and synthesis of polyhydroquinolines. The prepared catalyst was characterized by Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP‐OES), X‐ray Diffraction (XRD), thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM) measurements. This organometallic catalyst was recovered by the assistance of an external magnetic field from the reaction mixture and reused for seven continuous cycles without noticeable change in its catalytic activity.  相似文献   

12.
《中国化学会会志》2018,65(7):868-874
In this work, the NiFe2O4@TiO2/reduced graphene oxide (RGO) ternary nanocomposites with high saturation magnetization and catalytic efficiency have been synthesized through the following steps. First, graphene oxide was prepared using the modified Hummer's method. Second, the NiFe2O4 nanoparticles were successfully prepared using the hydrothermal method. Third, the core shell‐structured NiFe2O4@TiO2/RGO nanocomposite precursors were easily obtained through hydrolysis reaction. The morphology of NiFe2O4@TiO2/RGO nanocomposites was characterized from scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Moreover, the results of X‐ray diffraction (XRD) patterns proved that the TiO2 coating shell consisted of anatase. The vibrating sample magnetometer (VSM) measurements showed that the saturation magnetization value of NiFe2O4@TiO2/RGO ternary nanocomposites was 25 emu/g. The X‐ray photoelectron spectroscopy (XPS) analysis confirmed that only part of the graphite oxide (GO) was reduced to RGO in the ternary nanocomposite. The degradation experiments proved that NiFe2O4@TiO2/RGO nanocomposite exhibited the high catalytic efficiency and outstanding recyclable performance for rhodamine B (RhB).  相似文献   

13.
Micron‐sized monodisperse superparamagnetic polyglycidyl methacrylate (PGMA) particles with functional amino groups were prepared by a process involving: (1) preparation of parent monodisperse PGMA particles by the dispersion polymerization method, (2) chemical modification of the PGMA particles with ethylenediamine (EDA) to yield amino groups, and (3) impregnation of iron ions (Fe2+ and Fe3+) inside the particles and subsequently precipitating them with ammonium hydroxide to form magnetite (Fe3O4) nanoparticles within the polymer particles. The resultant magnetic PGMA particles with amino groups were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X‐ray diffractometry (XRD), and vibrating sample magnetometry (VSM). SEM showed that the magnetic particles had an average size of 2.6 μm and were highly monodisperse. TEM demonstrated that the magnetite nanoparticles distributed evenly within the polymer particles. The existence of amino groups in the magnetic polymer particles was confirmed by FTIR. XRD indicated that the magnetic nanoparticles within the polymer were pure Fe3O4 with a spinel structure. VSM results showed that the magnetic polymer particles were superparamagnetic, and saturation magnetization was found to be 16.3 emu/g. The Fe3O4 content of the magnetic particles was 24.3% based on total weight. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3433–3439, 2005  相似文献   

14.
Nanocellulose (NC) materials have some unique properties, which make them attractive as organic or inorganic supports for catalytic applications. Nanocatalysts with diameters of less than 100 nm are difficult to separate from the reaction mixture, therefore, magnetic nanoparticles (MNPs) were used as catalysts to overcome this problem. Fe3O4@NCs/BF0.2 as a green, bio‐based, eco‐friendly, and recyclable catalyst was synthesized and characterized using fourier‐transform infrared spectroscopy (FT‐IR), vibrating sample magnetometer (VSM), X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA) techniques. Fe3O4@NCs/BF0.2 was employed for the synthesis of 2,3‐dihydro‐1H‐perimidine derivatives via a reaction of 1,8‐diaminonaphthalene with various aldehydes at room temperature under solvent‐free conditions. The present procedure offers several advantages including a short reaction time, excellent yields, easy separation of catalyst, and environmental friendliness.  相似文献   

15.

Background

Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated.

Methods

For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples.

Results

The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature.

Conclusions

Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature.

Graphical abstract

  相似文献   

16.
《中国化学会会志》2018,65(7):875-882
Hollow Fe3O4@TiO2‐NH2/Pd as a light‐weight, magnetically heterogeneous catalyst was successfully prepared, and characterized by using different techniques including X‐ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDX), vibrating sample magnetometer (VSM) measurements, and thermogravimetric analysis (TGA). Then this heterogeneous catalyst was tested in the Suzuki cross‐coupling reaction, and the results confirmed the success of this method. The catalyst could be separated easily using an external magnet and reused at least in five runs successfully without any appreciable loss in its catalytic activity.  相似文献   

17.
Herein, for the first time, a direct Z‐scheme g‐C3N4/NiFe2O4 nanocomposite photocatalyst was prepared using facile one‐pot hydrothermal method and characterized using XRD, FT‐IR, DRS, PL, SEM, EDS, TEM, HRTEM, XPS, BET and VSM characterized techniques. The result reveals that the NiFe2O4 nanoparticles are loaded on the g‐C3N4 sheets successfully. The photocatalytic activities of the as‐prepared photocatalysts were evaluated for the degradation of methyl orange (MO) under visible light irradiation. It was shown that the photocatalytic activity of the g‐C3N4/NiFe2O4 nanocomposite is about 4.4 and 3 times higher than those of the pristine NiFe2O4 and g‐C3N4 respectively. The enhanced photocatalytic activity could be ascribed to the formation of g‐C3N4/NiFe2O4 direct Z‐scheme photocatalyst, which results in efficient space separation of photogenerated charge carriers. More importantly, the as‐prepared Z‐scheme photocatalyst can be recoverable easily from the solution by an external magnetic field and it shows almost the same activity for three consecutive cycles. Considering the simplicity of preparation method, this work will provide new insights into the design of high‐performance magnetic Z‐scheme photocatalysts for organic contaminate removal.  相似文献   

18.
Microwave-induced combustion with glycine, CTAB-assisted hydrothermal process with NaOH and NH3, EDTA assisted-hydrothermal methods have been applied to prepare NiFe2O4 nanoparticles for the first time. Structural and magnetic properties of the products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmison electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and electron spin resonance spectrometry (EPR). TEM measurements showed that morphology of the product depends on the synthesis method employed. The average cystallite size of NiFe2O4 nanoparticles was in the range of 14–59 nm as measured by XRD. The uncoated sample (Method A) had an EPR linewidth of 1973 Oe, the coated samples reached lower values. The magnetic dipolar interactions existing among the Ni ferrite nanoparticles are reduced by the coatings, which could cause the decrease in the linewidth of the EPR signals. Additionally, the linewidth increases with an increase in the size and the size distribution of nanoparticles.  相似文献   

19.
Supported palladium catalyst (Pd/Fe3O4@SiO2) was easily prepared by supporting PdCl2 on silica‐coated magnetic nanoparticles Fe3O4 in ethylene glycol. The as‐prepared sample was characterized by infrared spectroscopy (IR), X‐ray diffraction (XRD) and X‐ray photoelectron spectrometer (XPS). The formation of active specie Pd(0) was confirmed by XRD and XPS, and the Pd loading for the fresh and recovered catalyst was determined by atomic absorption spectroscopy (AAS). Pd/Fe3O4@SiO2 was employed for the synthesis of biphenyl derivatives via Suzuki reaction. In terms of the yield of biphenyl, the supported catalyst displayed nearly equal catalytic performance to that of homologous PdCl2 under microwave irradiation for 30 min but higher than that obtained by traditional heating method for 12 h. The catalytic performance of Pd/Fe3O4@SiO2 for Suzuki reactions involving various aryl halides and arylboronic acids were also examined. Impressive yield of biphenyl at 68.2% was obtained even in the presence of unreactive aryl chlorides. Pd/Fe3O4@SiO2 was recovered by a permanent magnet and directly reused in the next run, and no obvious deactivation was observed for up to 6 times. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

20.
Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named “lithium-ion” batteries. In this study, NiFe2O4 was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe2O4 nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m2/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite.  相似文献   

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