Microwave-assisted Solution Method Research Articles

Gas response enhancement of nanocrystalline LaFeO3 perovskite prepared using the microwave-assisted solution method

Gas response enhancement of nanocrystalline LaFeO3 perovskite prepared using the microwave-assisted solution method

STUDIES OF MAGNESIUM DOPED MnS NANOMATERIAL SYNTHESIZED BY MICROWAVE-ASSISTED SOLUTION METHOD

Manganese sulfide (MnS) is a wide band gap material which has the potential use in short wavelength optoelectronic devices, photo-catalysis, solar cells etc. To alter the various properties of MnS nanomaterial, it was decided to add magnesium (Mg) as the dopant. Mg-doped MnS nanomaterial was synthesized by microwave-assisted solution method. From XRD and HRTEM studies, the crystallite size of the sample was estimated. Optical characterization of the sample was done by recording the UV-visible-NIR spectrum. The luminescent properties of Mg-doped MnS nanomaterial was analysed. The functional groups of the sample was found by FTIR studies and thermal stability was checked by TG/DTA studies. Also, Mg-doped MnS nanomaterial was characterized by SEM, EDAX and SAED studies.

Synthesis, structural, morphological, optical and electrical studies of PANI / SnO2 nanocomposites

Tin Oxide (SnO2) nanoparticles were prepared by the microwave-assisted solution method. Aniline monomers were prepared and polymerization in the suspension of SnO2 to form nanocomposites material, in which SnO2 nanoparticle was embedded within the polyaniline chain (PANI). Structural, Optical, Morphology and AC electrical conductivity studies of the sample were carried out using power X-ray diffraction, Fourier Transform Infrared Spectroscopy, UV-Vis Spectroscopy, Scanning Electron Microscope, High-Resolution Transmission Electron Microscope and AC Impedance Spectroscopy. Powder XRD helped to confirm the formation of PANI/SnO2 composites and the crystallite size of the nanocomposite is found to be 16 nm. Structural changes of PANI due to the presence of SnO2 in PANI/SnO2 nanocomposites have been analyzed in FT-IR and UV-Vis spectrum. SEM images show the morphology of PANI/SnO2 nanocomposites. HRTEM images were observed and showed that the SnO2 was scattered and confirmed the PANI chain that formed a PANI/SnO2 nanocomposites material. AC conductivity was studied in the frequency between 10 Hz - 8 MHz. At higher angular frequencies, the nanocomposites exhibit almost the maximum value of AC electrical conductivity (σac) is found at 303K of SnO2 in PANI.

Enhanced Productivity of Parabolic Solar Still Using -Mno2 Nano Particles

Parabolic solar still of area 0.25m2 is designed using mild steel and its enhanced productive yield with -MnO2 nanoparticles had been analyzed. Microwave assisted solution method have been used to synthesis α-MnO2 nanoparticles. XRD analysis of prepared -MnO2 nanoparticles size is found to be 35 nm. FTIR revealed the chemical composition and interaction of functional groups of MnO2 nanoparticles. SEM image shows the aggregates are mostly particles with random shapes. HRTEM image confirms the average particle size was around 35 nm. From the optical study it is inferred that the energy band gap value as 2.69 eV and the conductivity of prepared nanoparticles is found to be in the order of 10-7 S cm-1. Thermal stability of synthesized MnO2 nanoparticle has been analyzed with the help of TG study. Electrical conductivity of MnO2 have is in the order of 2.35×10 -7 Scm-1 as calculated from AC impedance spectroscopy. Heat Transfer phenomena under internal and external transfer modes along with thermophysical properties such as thermal conductivity, dynamic viscosity, density and latent heat of distillate yield is calculated. Instantaneous efficiency of parabolic solar still without and with MnO2 nanoparticles are found to be in the range of 11.52% to 40.71% and 10.94% to 46.32%. Similarly, overall efficiency is found to be 30.01% and 35.27%. The distillate productivity is mainly depended on the thermal parameters such as saturated vapor pressure and latent heat is observed as 8762 J/Kg, 9510 J/Kg, 2391875 Pa and 2388435 Pa for parabolic still in two modes of study.

Structural, Biological and Photocatalytic Properties of Zirconium Oxide Nanoparticles Synthesized by Microwave Assisted Solution Method

Zirconium dioxide nanoparticles have been synthesized by microwave assisted solution method. The prepared nanoparticle have been characterized by powder X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, ultraviolet- diffuse reflectance spectra, thermo gravimetric-differential thermal analysis and also evaluated for their antibacterial activity against bacterial strains. XRD pattern showed the prepared ZrO2 nanoparticles having monoclinic structure which shows the average crystalline size around 20 nm. SEM image showed the particles are spherical shape with agglomeration due to the intermolecular attraction for small particle size. From the UV-DRS,the energy band gap has found to be 4.9 eV. The results of antibacterial activity showed that the nanocrystalline zirconium dioxide had an important inhibitory activity against pseudomonas arginosa. Photocatalytic degradation of methylene blue dye in the presence of ZrO2 nanoparticle under sunlight has been investigated at various times. The 75 % of methylene blue dye has been degraded at 140 min of sunlight irradiation. The photocatalytic activity of catalyst has been high for 40 mg/50 mL sample concentration.

Synthesis and Investigation of Antimicrobial Activity of Tin Oxide Nanoparticles by Microwave Assisted Solution Method

Synthesis and Investigation of Antimicrobial Activity of Tin Oxide Nanoparticles by Microwave Assisted Solution Method

A simple route for the preparation of nanostructured GdCoO3 via the solution method, as well as its characterization and its response to certain gases

Abstract This work presents the synthesis of perovskite GdCoO3 by a microwave-assisted solution method in order to test its possible application as a gas sensor. The crystal evolution, structure, composition, texture, morphology, and particle size were analyzed by X-ray diffraction, scanning and transmission electron microscopies, and nitrogen physisorption. Our synthesis route allowed to obtain GdCoO3 at lower temperatures and shorter reaction times than conventional methods. Measurements confirmed the formation of porous GdCoO3 microbases with a thickness of 7–13 μm. The GdCoO3 microbases were constituted by nanoparticles of size 10–20 nm. Additionally, crystallites of size 85–130 nm were observed distributed on the surface of the microbases, covering a surface area of around 19 m2/g. Pellets elaborated from GdCoO3 powders were tested as sensors in carbon monoxide and propane gaseous atmospheres at different temperatures and gas concentrations. The GdCoO3 showed a good performance as a gas sensor compared to other similar oxides. The oxide was clearly sensitive to the studied gases even at concentrations as low as 5 ppm at a temperature of 100 °C. The response of the material was homogeneous and increased with both the increase in temperature and gas concentration.

Microwave-assisted solution synthesis and photocatalytic activity of Ag nanoparticles supported on ZnO nanostructure flowers

Ag nanoparticles supported on the surface of three-dimensional (3D) flower-like ZnO nanostructure were synthesized by a microwave-assisted solution method. The obtained products were characterized by X-ray diffraction analysis, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectrophotometry, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The analytical results confirmed homogeneously distributed Ag nanoparticles supported on the surface of flower-like ZnO nanostructure. The photocatalytic effect of the heterostructure Ag/ZnO nanocomposites was investigated using photodegradation under ultraviolet (UV) light of methylene blue as model dye. The heterostructure Ag/ZnO nanocomposites exhibited much higher photocatalytic activity than pure ZnO flowers. The improved photocatalytic properties are attributed to formation of a Schottky barrier at the metal–semiconductor interface of the Ag/ZnO nanocomposites.

NiCo2S4 nanosheet thin film counter electrodes prepared by a two-step approach for dye-sensitized solar cells

NiCo2S4 nanosheet thin films were prepared on the fluorine-doped tin oxide (FTO) conductive glass by a two-step approach. First, NiCo2O4 nanosheets were synthesized by rapid microwave-assisted solution method, and then they were converted to NiCo2S4 nanosheets by solution-based vulcanization reaction. The dye-sensitized solar cells (DSSCs) with the NiCo2S4 as the counter electrode (CE) could reach a power conversion efficiency of 5.81%, exceeding a typical efficiency of 5.02% in DSSCs based on the sputtered Pt counter electrode. The synthesis simplicity, time efficiency, low cost, and excellent electrocatalytic characteristic make the NiCo2S4 nanosheet thin film promising as CE material for DSSC applications.

Phase Separation Derived Core/Shell Structured Cu11 V6 O26 /V2 O5 Microspheres: First Synthesis and Excellent Lithium-Ion Anode Performance with Outstanding Capacity Self-Restoration.

Novel amorphous vanadium oxide coated copper vanadium oxide (Cu11 V6 O26 /V2 O5 ) microspheres with 3D hierarchical architecture have been successfully prepared via a microwave-assisted solution method and subsequent annealing induced phase separation process. Pure Cu11 V6 O26 microspheres without V2 O5 coating are also obtained by an H2 O2 solution dissolving treatment. When evaluated as an anode material for lithium-ion batteries (LIBs), the as-synthesized hybrid exhibits large reversible capacity, excellent rate capability, and outstanding capacity self-recovery. Under the condition of high current density of 1 A g-1 , the 3D hierarchical Cu11 V6 O26 /V2 O5 hybrid maintains a reversible capacity of ≈1110 mA h g-1 . Combined electrochemical analysis and high-resolution transmission electron microscopy observation during cycling reveals that the amorphous V2 O5 coating plays an important role on enhancing the electrochemical performances and capacity self-recovery, which provides an active amorphous protective layer and abundant grain interfaces for efficient inserting and extracting of Li-ion. As a result, this new copper vanadium oxide hybrid is proposed as a promising anode material for LIBs.

Cr doping assisted tuning of functional properties of ZnO nanorods prepared by fast solution route

In this work, single-crystalline Zn1−x Cr x O (0.0 ≤ x ≤ 0.05) nanorods were prepared by a facile microwave-assisted solution method, and their significant correlation between structural, optical, morphological and magnetic properties was investigated. X-ray diffraction and transmission electron microscopy (TEM) results showed that Cr-doped ZnO was comprised of single-phase nature with hexagonal wurtzite structure. Field emission scanning electron microscopy and TEM micrographs suggested that the pure nanorods with an average length of ~2 µm and a diameter in the range of 150–200 nm, respectively, were observed. Interestingly, the size of nanorods decreased with the increase in Cr concentration in ZnO. There is striking similarities between changes in the lattice volume, bandgap energy, morphology and the saturation magnetization caused by Cr doping. Unit cell volume, value of saturation magnetization and bandgap was decreased with the increase in Cr doping. Zn vacancies, together with Cr doping, played an important role in the ferromagnetic origin of Zn1−x Cr x O nanorods. Single-crystalline Zn1−x Cr x O (0.0 ≤ x ≤ 0.05) nanorods were prepared by a facile microwave-assisted solution method showing the relationship between lattice volume, bandgap energy, morphology and the saturation magnetization.

Synthesis and characterization of Cu2ZnSnS4 nanocrystals prepared by microwave irradiation method

In this study, we report a rapid and single-step synthesis of Cu2ZnSnS4 (CZTS) nanocrystals using microwave-assisted solution method. The influence of reaction temperature and reaction time on the phase purity, crystallographic structure, morphology and optical property of CZTS particles were investigated using X-ray diffraction, Raman spectroscopy, scanning electronic microscope, transmission electron microscopy and ultraviolet–visible spectrometer. Results revealed that the single kesterite CZTS particles with no secondary phase can be obtained by preparing samples at minimal temperature of 170 °C. The sphere-like particles, each of which contains many nanocrystals, decrease effectively in size when increasing the reaction temperature from 170 to 200 °C. The CZTS nanocrystals have an optical band gap around 1.5 eV, which is optimal for photovoltaic applications. In addition, minimal reaction time of 10 min is also essential for the growth of single kesterite CZTS. Our study demonstrated that appropriate reaction temperature and reaction time are crucial for the synthesis of high-quality CZTS by microwave irradiation method.

ZnO nanorods with low intrinsic defects and high optical performance grown by facile microwave-assisted solution method.

Vertically aligned ZnO nanorods were grown at 90 °C by both microwave synthesis and traditional heated water bath method on Si (100) substrate with a precoated ZnO nanoparticle seed layer. A detailed comparison in the morphology, defects, and optical properties of the ZnO nanorods grown by the two methods across the pH range of 10.07-10.9 for microwave synthesis and conventional heated water bath method was performed using scanning electron microscopy, photoluminescence, and X-ray photoelectron spectroscopy. The results show that the microwave route leads to more uniformly distributed nanorods with a lower density of native defects of oxygen interstitials and zinc vacancies. The microwave synthesis presents a promising new approach of fabricating metal oxide nanostructures and devices toward green applications.

Rapid synthesis of Cu2ZnSnS4 nanocrystalline thin films directly on transparent conductive glass substrates by microwave irradiation

In this letter, a rapid and single-step microwave-assisted solution method was proposed to grow Cu2ZnSnS4 (CZTS) thin films directly on transparent conductive fluorine-doped tin oxide (FTO) substrates. The CZTS thin films synthesized in one pot without any post-treatment are characterized by X-ray diffraction, Raman spectroscopy, scanning electronic microscope, transmission electron microscopy, X-ray photoelectron spectrometer and UV–vis spectrophotometer. The CZTS thin films were single kesterite structure and composed of uniform sphere-like nanocrystalline particles with an average diameter of about 250nm. The optical band gap is found to be 1.58eV, which is suitable for photovoltaic applications.

Can microwave assisted in situ reduction of supported Pt nanoparticles challenge the chemical method in controlling the dispersion profile-catalytic performance relationship?

In this comparative study of dispersion profile-catalytic performance relationships, Pt (of 0.3, 0.6 and 0.9 wt%) was supported on mesoporous silica surface via microwave assisted solution method or rotary chemical evaporation method in the in situ reduction step.

One-step microwave-assisted synthesis of Ag/ZnO/graphene nanocomposites with enhanced photocatalytic activity

Abstract Ag/ZnO/graphene (Ag/ZnO/G) nanocomposites were successfully synthesized by a facile low-temperature microwave-assisted solution method. The morphology and phase structure of the prepared samples were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The photocatalytic performance of the obtained products were evaluated by analyzing the degradation of methyl orange (MO) solution under UV irradiation. The Ag/ZnO/graphene nanocomposites showed higher photocatalytic efficiency than ZnO or Ag/ZnO. Photocatalytic activity of Ag/ZnO/graphene nanocomposites with different graphene content was studied. Firstly the photocatalytic efficiency of the Ag/ZnO/graphene nanocomposites increased with the increase of graphene oxide (GO) content from 0 to 1%, then the photocatalytic efficiency decreased while the percent of GO addition reached 2%. The photostability testing of the Ag/ZnO/graphene nanocomposites with 1% GO content showed that the catalyst has excellent photocatalytic activity and photostability for the degradation of MO. It is believed that this facile, rapid microwave-assisted strategy is scalable and can be applied to synthesize other metal/semiconductor oxide/graphene nanocomposites for different applications in different fields.

Doping dependent properties of Cr-doped ZnO nanostructures prepared by microwave irradiation.

In this work, undoped and Cr-doped single-crystalline ZnO nanorods were prepared by a facile microwave assisted solution method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that Cr-doped ZnO was comprised of single phase nature with hexagonal wurtzite structure up to 5% Cr doping, however, secondary phase ZnCr2O4 appeared upon further increasing the Cr dopant concentration. Field emission scanning electron microscopy (FESEM) and TEM micrographs suggested that the undoped nanorods with an average length of -~2 μm and a diameter in the range of 150-200 nm, respectively were observed. Interestingly, the size of nanorods decreased with the increase of Cr concentration in ZnO. Optical studies depicted that the energy bandgap was decreased with the increase of Cr concentration. Raman scattering spectra of Cr-doped ZnO revealed the lower frequency shift of E2(high) phonon mode with the increase in concentration of Cr dopant, suggested the successful doping of Cr into Zn site in ZnO. Magnetic studies showed that Cr-doped ZnO exhibited room temperature ferromagnetism (RTFM) and the value of magnetization was continuously decreased with the increase in Cr doping.

Doughnut-shaped hierarchical Cu2ZnSnS4 microparticles synthesized by cyclic microwave irradiation

For the first time, hierarchical doughnut-shaped Cu2ZnSnS4 (CZTS) microparticles were synthesized by microwave-assisted solution method. N,N-dimethylformamide and polyvinylpyrrolidone (PVP) were used as solvent and stabilizing agent respectively, and the results showed that PVP played an important role in the formation of hierarchical nanostructures. Structural analysis by X-ray diffraction and Raman studies confirmed the formation of single phase kesterite CZTS. Morphological analysis by scanning electron microscope showed doughnut-shaped CZTS microparticles composed of large number of interpenetrating nanoplates. Optical analysis by UV–Vis diffused reflectance spectra showed strong absorption in the visible region with an optical band gap of 1.54eV. Asymmetric broad emission bands around 1.55eV and 1.30eV were observed in the photoluminescence spectrum. A possible formation mechanism for doughnut-shaped CZTS microparticles was put forward and discussed briefly.

Facile growth of ZnO nanorod arrays by a microwave-assisted solution method for oxygen gas sensing

This work reports the growth of vertically aligned and single-crystalline zinc oxide (ZnO) nanorod arrays on the silicon (Si) substrate using a microwave-assisted solution method. The x-ray diffraction and selected area electron diffraction patterns indicated that the ZnO nanorods were grown preferentially oriented in the (001) direction and have single phase nature with a wurtzite structure. Field emission scanning electron microscopy and transmission electron microscopy results showed that the length and diameter of the well aligned rods were about ~500nm and ~80nm, respectively. Raman scattering spectra of ZnO nanorod arrays revealed the characteristic E2high mode that is related to the vibration of oxygen atoms in the wurtzite ZnO. The gas-sensing properties of the ZnO nanorod arrays for oxygen with different concentration were measured at room temperature. It was found that the value of resistance increased with the increase of oxygen gas concentration in the chamber. The ZnO nanorod arrays exhibited high sensitivity and rapid response–recovery characteristics to oxygen gas and can detect low concentration as 5, 10, 15 and 20 parts per million.

Microwave-assisted synthesis of SnO2 nanorods for oxygen gas sensing at room temperature

High-quality single-crystalline SnO2 nanorods were synthesized using a microwave-assisted solution method. The nanorods were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible and Raman spectroscopy, Brunauer–Emmett–Teller (BET), and electrical resistance measurements. The XRD pattern indicated the formation of single-phase SnO2 nanorods with rutile structure. FE-SEM and TEM images revealed tetragonal nanorods of about 450–500 nm in length and 60–80 nm in diameter. The nanorods showed a higher BET surface area of 288 m2/g, much higher than that of previously reported work. The Raman scattering spectra indicated a typical rutile phase of the SnO2. The absorption spectrum showed an absorption peak centered at 340 nm, and the band-gap value was found to be 3.64 eV. The gas-sensing properties of the SnO2 nanorods for oxygen gas with different concentrations were measured at room temperature. It was found that the value of resistance increased with the increase in oxygen gas concentration in the test chamber. The SnO2 nanorods exhibited high sensitivity and rapid response-recovery characteristics to oxygen gas, and could detect oxygen concentration as low as 1, 3, 5, and 10 ppm.