Reflux Condensation Method Research Articles

Molecular manganese catalyst anchored on Bi2MoO6 with enhanced photogenerated charges separation for efficient visible-light photoreduction of CO2

Metal–organic hybrid composites are considered stable photocatalysts that exhibit effective CO2 adsorption capability and high charge separation efficiency. Here, the reflux condensation method was used to synthesize organometallic complexes of 2,2-bipyridine-4,4-bisphosphonic acid tricarbonyl manganese bromide (MnP), which were then phosphate anchored onto Bi2MoO6 via a facile self-assembly method. The resulting Bi2MoO6/MnP (150:1) composites catalysts exhibited efficient photocatalytic reduction of CO2 under visible light. The photocatalysts were systematically characterized via XRD, SEM, TEM, BET analysis, FTIR and UV–Vis. Visible light catalytic reduction products were detected qualitatively and quantitatively by ion chromatography and gas chromatography. The results demonstrate that loaded MnP reveal unique C=O, C–C characteristic peak and a peak fluorescence intensity that is less than 50% before loading. Furthermore, a remarkable CO production of turnover number TONCO = 123 and methanol yield of 95 µmol g−1 were obtained at a reaction time of 8 h under optimal conditions. The results due to the MnP in the composites not only enhanced charge carrier extraction but also improved photocatalytic reduction CO2 performance. Overall, the Bi2MoO6/MnP composites exhibit good potential in the photocatalysts fields.

Studies on the High Thermal Conduction Fluid by Incorporating CuO Nanoparticles in a Liquid Coolant

Abstract CuO nanoparticles have shown a high level of interest in the field of nanoscience and nanotechnology as these possess an ability to change material’s properties drastically when incorporated in the matrix. The present work is deemed to the synthesis of highly pure copper oxide nanoparticles (CuO) via reflux condensation method and their use as nanofluid for high thermal conduction applications. The synthesized CuO nanoparticles have been characterized by X-ray diffraction technique (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDAX) and thermogravimetric analysis (TGA). XRD technique shows the crystallite size of CuO nanoparticles of 8-17 nm, the particle size of CuO nanoparticles are 8-19 nm and the shape of nanoparticles are spherical as obtained from TEM analysis. Thermal stability of nanoparticles is analyzed by TGA, no significant loss is found in the range of 100 – 600 °C. EDAX gives the purity of the CuO nanoparticles. Since CuO nanoparticles have shown a high thermal energy rejection, it is thought to give faster heat rejection from the heat sink to the environment. The studies were conducted on the change in the thermal conduction of a liquid system to the environment with respect to the weight of nanoparticles dispersed in a fluid. The liquid and nanofluids were characterized for thermal conduction measurement by KD2 pro thermal analyzer. Satisfactory results have been obtained from the study show that the CuO nanoparticles increase the thermal conduction of a coolant by increasing its effectiveness and behave as an ideal coolant.

Synthesis and characterization of TiO2 quantum dots by sol gel reflux condensation method

Owing to their high specific surface area, titanium dioxide (TiO2) quantum dots (QDs) offer superior properties for UV radiation harvesting from solar spectrum for applications such as self-cleaning surfaces and removal of organic contaminants. In this work, a novel sol-gel reflux condensation route developed to produce TiO2 QDs is reported. The process involved using titanium tetra-isopropoxide (TTIP) as the precursor that was hydrolyzed and then subjected to reflux condensation for 24 h. Subsequent drying and annealing treatments produced QDs with a relatively high yield of 33%. TEM examination revealed spherical QD morphology with an average crystallite size of 5–7 nm. This was also confirmed from QD size calculation involving Scherrer equation for the most intense peak in the x-ray diffraction (XRD) pattern. Both XRD and Raman spectroscopy studies cofirmed the crystalline anatase phase formation. From UV/Vis data and the Tauc plot, the energy band gap value (Eg) was computed to be ~3.76 eV.

Synthesis, structural characterization and antimicrobial activities of polyindole stabilized Ag-Co3O4 nanocomposite by reflux condensation method

Polyindole stabilized silver‒cobalt oxide (Pind/Ag‒Co3O4) nanocomposites were synthesized, characterized and evaluated for their antibacterial and antifungal activities. Polyindole, cobalt oxide and Pind/Ag‒Co3O4 were prepared by chemical oxidative polymerization, co-precipitation and reflux condensation method, respectively. Colloidal nanoparticles of polyindole, cobalt oxide and nanocomposite were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction pattern (XRD), scanning electron microscope with energy dispersive X-ray diffraction study (SEM-EDAX) and high resolution transmission electron microscope with selected area diffraction (HRTEM-SAED). FTIR spectra revealed the functional group’s transformation of cobalt oxide nanoparticles. The crystalline nature of the samples was confirmed by XRD study. The SEM images revealed the various shapes and surface morphology of the nanocomposites. Further, the elemental composition was confirmed by EDAX. The HRTEM images showed shapes such as spherical, cylindrical, rectangular, rods, oval and square. The average particle size of the nanocomposites found to be ∼20 nm which is in good agreement with XRD analysis in terms of the size of the crystalline. The Pind/Ag‒Co3O4 nanocomposites exhibited improved antibacterial and antifungal activities against pathogenic bacteria and fungi. Hence, these nanocomposites could be used as a potential candidate for the biomedical applications.

Synthesis, Characterization, and Antibacterial Activity of Polyindole/Ag–Cuo Nanocomposites by Reflux Condensation Method

ABSTRACTPolyindole-based silver and copper oxide (polyindole/Ag–CuO) nanocomposites were synthesized using reflux condensation method by varying the concentrations of polyindole and silver nitrate with copper oxide in N2 atmosphere. They were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The SEM images revealed fascinating shapes of CuO nanoparticles. The FTIR and XRD confirmed the functional group transformation and crystalline natures of silver and CuO existed in the nanocomposites. The polyindole/Ag–CuO nanocomposites were examined for antibacterial activity and found to exhibit the antibacterial activity against pathogenic bacteria.

Decorating mechanism of Mn3O4 nanoparticles on reduced graphene oxide surface through reflux condensation method to improve photocatalytic performance

A simple and effective route has been developed to synthesize reduced graphene oxide/Mn3O4 (rGO/Mn3O4) nanocomposites in which Mn3O4 nanoparticles are grown on reduced graphene oxide surface. The synthesized nanocomposite materials were characterized by different techniques. X-ray diffraction (XRD) confirmed the formation of rGO/Mn3O4 nanocomposites and transmission electron microscopy (TEM) study revealed that Mn3O4 nanomaterials with average size 5–8 nm were embedded on rGO surface and with the increase of Mn3O4 content the particle size increases due to aggregation. Furthermore, Mn3O4 nanomaterials were successfully applied to degrade the organic dyes in water but compared to Mn3O4 nanomaterials the rGO/Mn3O4 nanocomposites are found to most heavily enhance the dye degradation efficiency under solar light irradiation due to large surface area of rGO surface. Moreover, the rGO/Mn3O4 nanocomposite materials exhibited good photostability, which was proved by their consistent photocatalytic performance.

Enzyme free Thiol capped CdS Quantum dots based sensing method for the detection of Malathion

This study was focused to develop a cost effective and simple sensing method for Malathion using Thioglycolic acid (TGA) capped Cadmium Sulfide (CdS) quantum dots. Quantum dots (QDs) were synthesized by reflux condensation method and capped with TGA. QDs were characterized by UV-Vis spectroscopy, Spectrofluorometer, FT-IR and HR-TEM. Size of the TGA capped QDs were found to be 2.5 nm. Interaction of Malathion and quantum dots was analyzed by Spectrofluorometer based on photoluminescence (PL) quenching. The lowest detection limit of Malathion was found to be 2 ppb which was observed from the minimum interference it could cause in the PL spectrum.

Synthesis of CdS-decorated RGO nanocomposites by reflux condensation method and its improved photocatalytic activity

The cadmium sulfide nanoparticle-reduced graphene oxide (CdS/RGO) nanocomposite with intimate nano-interfacial contact was successfully prepared via a facile condensation process in dilute dimethylformamide (DMF) aqueous solution. Numerous CdS nanoparticles featuring a size of around 10 nm were homogeneously anchored on 2D nanosheets. During the formation of CdS/RGO nanocomposite, graphene oxide (GO) was transformed into RGO simultaneously. The solar-driven degradation of Rhodamine B (RhB) was conducted to detect the activity of the as-prepared CdS/RGO nanocomposite. Significantly, the photocatalytic activity of CdS/RGO nanocomposite was almost three times higher than that of pure CdS. The charge transfer and photogenerated active hydroxyl radicals (⋅OH) were investigated to study the mechanism of excellent photocatalytic property. The synthetic method provided a valuable opportunity to fabricate large-scale novel graphene-based materials with superior catalytic activity.

Solution processing of CuSe quantum dots: Photocatalytic activity under RhB for UV and visible-light solar irradiation

Exploit of photodegradation and photocatalytic activity of large scale synthesis of (CuSe) copper selenide semiconductor quantum dots was reported. The obtained nanocrystals were characterized by X-ray diffraction (XRD), UV-visible absorption spectroscopy (UV-vis) photoluminescence (PL) and high resolution transmission electron microscopy (HRTEM). The crystalline, nearly monodisperse with uniform size were synthesized by the reflux condensation method. This method promises a range of possibilities for the preparation of CuSe materials with enhanced properties. Experimental investigation shows the nanoscale photocatalysts with high surface area, small particle size and high crystallinity is of current interest in nanophase materials. The chemical composition of the CuSe samples and the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS). We present our investigations to the shape and size of the quantum dots and are good agreement with experimental results.

Novel CuCr2O4 embedded CuO nanocomposites for efficient photodegradation of organic dyes

Novel photocatalyst based on CuO–CuCr2O4 nanocomposites was synthesized for different Cr3+ concentration by reflux condensation method, and their photocatalytic activity was evaluated by monitoring the photodegradation of methyl orange (MO) and methylene blue dyes (MB) under UV light irradiation. Phase evolution by X-ray diffraction showed monoclinic CuO and tetragonal CuCr2O4 as the components of the prepared nanocomposites. Morphological analysis by scanning electron microscope and transmission electron microscope revealed that the incorporation of Cr3+ in CuO lattice alters the morphology of CuO from microsphere to cluster shape. Photoluminescence spectra of CuO–CuCr2O4 nanocomposites exhibited reduced PL emissions compared to pure CuO, indicating the low recombination rate of photogenerated electrons and holes. As expected, the CuCr2O4 loaded CuO showed enhanced photocatalytic activity for MO and MB dyes, and the kinetic studies suggest that the degradation follows pseudo-first-order kinetics. The enhanced photocatalytic activity of CuO–CuCr2O4 nanocomposites can be attributed to the presence of CuCr2O4 as an electron acceptor, which improves the effective charge separation in CuO.

Photocatalytic activity of hierarchical CuO microspheres synthesized by facile reflux condensation method

Flower-shaped hierarchical CuO microspheres consisting of interpenetrating nanosheets were successfully synthesized by reflux condensation method without using any surfactant or templates. X-ray diffraction revealed the formation of single phase CuO exhibiting monoclinic crystal structure. Scanning electron microscopy and transmission electron microscopy confirmed the formation of hierarchical flower-shaped CuO microspheres made up of nanosheets as building blocks. UV–vis diffused reflectance spectroscopy showed a steep absorption between 700 and 950nm, and the corresponding band gap of CuO nanoparticles was found to be 1.59eV. To explore the potential capability of flower-shaped CuO microspheres for wastewater treatment, the photocatalytic activity of CuO nanostructures was evaluated by monitoring the photodegradation of methyl orange (MO) and methylene blue (MB) dyes in the presence of hydrogen peroxide under UV light irradiation. Experimental results demonstrated that CuO hierarchical architecture possesses good photocatalytic activity towards MO and MB dyes, indicating the feasibility of using CuO for the effective removal of organic contaminants from wastewater.

Effect Of Synthesis Time On Structural, Optical And Electrical Properties Of CuO Nanoparticles Synthesized By reflux Condensation Method

CuO nanopowder oxide was synthesized by reflux condensation method without any surfactants or templates, using copper nitrate in deionized water and aqueous ammonia solution. The structural, optical and electrical properties of the sample were investigated using X-ray diffraction (XRD), FT-IR, UV-visible spectroscopy and impedance spectroscopy measurements. The X-ray diffraction patterns revealed that CuO nanoparticles (NPs) was formed in pure monoclinic phase and good crystalline quality, whose NPs sizes were of the order 25 nm which an average size can be tailored by the synthesis time. FT-IR spectra of CuO NPs used to detect the possible adsorbed species on the CuO materials. In addition, the peaks at 529 and 604 cm -1

Improved photocatalytic activity of ZnO coupled CuO nanocomposites synthesized by reflux condensation method

Nanostructured CuO–ZnO nanocomposites were successfully synthesized for different Zn2+ concentrations by reflux condensation method without using any surfactant, and their photocatalytic activity was evaluated using methyl orange and methylene blue dyes under UV light irradiation. XRD revealed the formation of CuO–ZnO nanocomposites, composing of monoclinic CuO and hexagonal ZnO. XPS analysis revealed that CuO–ZnO nanocomposites are made up of Cu(II), Zn(II) and O. FESEM and TEM images showed that pure CuO exhibit 3D flower-like microstructure, while the CuO–ZnO nanocomposites prepared for different Zn2+ concentrations have 3D flower-like CuO, microstructure adorned with rod-like ZnO particles. UV–Vis DRS showed absorption bands corresponding to CuO and ZnO around 960nm and 395nm, respectively. PL spectra of CuO–ZnO nanocomposites exhibited reduced PL emissions compared to pure CuO, indicating the low recombination rate of photogenerated electrons and holes. Photodegradation assay revealed that catalytic activity of CuO–ZnO nanocomposites increased with Zn2+ concentration, and also effectively degrade methyl orange and methylene blue dyes when compared to pure CuO. The enhanced photocatalytic activity of CuO–ZnO nanocomposites were mainly ascribed to the reduced recombination and efficient separation of photogenerated charge carriers. The possible mechanism for the improved photocatalytic activity of CuO–ZnO nanocomposites was proposed.

Development of NiO-Co3O4 nano-ceramic composite materials as novel photocatalysts to degrade organic contaminants present in water

Novel ceramic oxides have been increasingly focused in recent years because of their potentialapplications in environmental purification especially to treat organic contaminants present in water. In thisresearch work, a set of NiO-Co3O4 nano-ceramic composite materials were prepared by a simple refluxcondensation method using nickel acetate / cobalt acetate as precursor salts, sodium monododecyl sulphate(SDS) as a surfactant and N,N-Dimethylformamide (DMF) as solvent. The prepared nano-ceramic compositeswere calcined at different temperatures such as 200, 400, 600 and 800oC for 2 hours each to get the phase pureproduct. XRD results revealed that all the samples indexed to a cubic crystalline geometry. The presence ofmetal-oxygen bond (Ni-O and Co-O) was confirmed by FTIR spectroscopy. The presence of Ni, Co and O inthe sample was confirmed by EDAX analysis. The existence of particles in nanometer range was shown bySEM. The particle size analysis by light scattering method also confirmed the particles in nanometer range(approximately 270 nm) in all the three samples. The optical behavior of the materials was studied by UV-Visand PL spectrophotometer. Photocatalytic activity studies carried out with NiO-Co3O4 (1.0:1.0) nano-ceramiccomposites in presence of organic dyes such as, rhodamine B and methyl orange dyes under UV lightirradiation (for two hours) resulted in the degradation of 77% and 84% respectively.

Influence of growth and photocatalytic properties of copper selenide (CuSe) nanoparticles using reflux condensation method

Influence of reaction conditions on the synthesis of copper selenide (CuSe) nanoparticles and their photo degradation activity is studied. Nearly monodispersed uniform size (23–44nm) nanoparticles are synthesized by varying the reaction conditions using reflux condensation method. The obtained nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV–visible absorption spectroscopy. The X-ray diffraction analysis of the sample shows the formation of nanoparticles with hexagonal CuSe structure. The result indicates that on increasing the reaction time from 4 to 12h, the particle size decreases from 44 to 23nm, but an increase in the reaction temperature increases the particle size. The calculated band gap Eg is ranging from 2.34 to 3.05eV which is blue shifted from the bulk CuSe (2.2eV). The photocatalytic degradation efficiency of the CuSe nanoparticles on two organic dyes Methylene blue (MB) and Rhodamine-B (RhB) in aqueous solution under UV region is calculated as 76 and 87% respectively.

Flower-shaped CuO Nanostructures: Synthesis, Characterization and Antimicrobial Activity

In the present work, flower-like CuO nanostructures were synthesized by reflux condensation method without using any surfactants or templates. Structural analysis by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman studies revealed the formation of highly crystalline single phase CuO, exhibiting monoclinic structure. Morphological analysis by field emission scanning electron microscopy (FESEM) showed flower-shaped CuO hierarchical architecture made up of interpenetrating self-assembled nanosheets. Optical analysis by UV–Vis diffused reflectance spectra (DRS) exhibited considerable blue-shift in the optical band gap due to quantum confinement effect. Photoluminescence (PL) spectrum showed both UV as well as visible emissions. The antibacterial activity of flower-shaped CuO nanostructures were tested against gram-positive (Bacillus subtilis, Bacillus thuringiensis) and gram-negative (Salmonella paratyphi, Salmonella paratyphi-a, Salmonella paratyphi-b, Escherichia coli and Pseudomonas aeruginosa) bacteria. Also, the antifungal activity of CuO was investigated against Aspergillus niger, Rhizopus oryzae, Aspergillus flavus, Cladosporium carrionii, Mucor, Penicillium notatum and Alternaria alternata. Results demonstrate that the flower-shaped CuO nanostructures act as an effective antimicrobial agent against pathogenic bacteria and fungi.

Synthesis, morphology, optical and photocatalytic performance of nanostructured β-Ga2O3

Fine powders of β-Ga2O3 nanostructures were prepared via low temperature reflux condensation method by varying the pH value without using any surfactant. The pH value of reaction mixture had great influence on the morphology of final products. High crystalline single phase β-Ga2O3 nanostructures were obtained by thermal treatment at 900°C which was confirmed by X-ray diffraction and Raman spectroscopy. The morphological analysis revealed rod like nanostructures at lower and higher pH values of 6 and 10, while spindle like structures were obtained at pH=8. The phase purity and presence of vibrational bands were identified using Fourier transform infrared spectroscopy. The optical absorbance spectrum showed intense absorption features in the UV spectral region. A broad blue emission peak centered at 441nm due to donor–acceptor gallium–oxygen vacancy pair recombination appeared. The photocatalytic activity toward Rhodamine B under visible light irradiation was higher for nanorods at pH 10.

Improved sensing performance from methionine capped CdTe and CdTe/ZnS quantum dots for the detection of trace amounts of explosive chemicals in liquid media

Water soluble methionine functionalized CdTe quantum dots (QDs) and CdTe/ZnS core–shell QD samples have been prepared by a reflux condensation method and have been used to detect explosive chemicals, such as dinitrotoluene (DNT), nitrotoluene (NT) and nitrobenzene (NB) in liquid media. Meisenheimer complex formation between the QD surface attached methionine and aromatic explosive molecules has helped to detect them selectively via a fluorescent quenching process. Fluorescence quenching occurred because of the transfer of excited electrons from QD to the explosive molecules. Depending upon the number of nitro groups present on the explosive molecule, the quenching efficiency of different analytes varied. Due to surface passivation and inductive effects, the methionine capped CdTe/ZnS core–shell quantum dot sample resulted in the maximum quenching constant.

Effect of Surfactants in the Synthesis of NiO Nanoparticles by Colloidal Thermal Assisted Reflux Condensation Method

Nickel oxide (NiO) nanoparticles were prepared by colloidal thermal assisted reflux condensation method using nickel acetate (precursor salt) and N, N - Dimethylformamide - DMF (solvent) with or without the addition of surfactants such as cetyl trimethyl ammonium bromide (CTAB), polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and sodium monododecyl sulphate (SDS) respectively. Finally, the prepared samples products were calcined at different temperatures systematically such as at (...)

Enhanced photocatalytic performance of novel self-assembled floral β-Ga2O3 nanorods

Self-assembled monoclinic phase of novel floral β-Ga2O3 nanorods were prepared using reflux condensation method by controlled precipitation of metal cations with urea. The structural and morphological properties were investigated by X-ray powder diffraction, Raman spectroscopy and Scanning electron microscope. Single-crystalline nanorods with size 100 nm involved in the self-assembly process to form flowery pattern have diameter ∼1 μm with surface area 40.8 m2/g confirmed from transmission electron microscope and Brunauer–Emmett–Teller analysis. The band gap energy of 4.59 eV was evaluated from the UV–vis diffuse reflectance spectrum and the photoluminescence spectrum displayed the characteristic luminescence and blue-light emission peaks. Further, the photocatalytic activity of novel β-Ga2O3 floral nanorods towards the photodegradation of Rhodamine B in aqueous solution under ultra violet light irradiation showed better photocatalytic activity than the commercial photocatalyst Degussa P25 TiO2.