Sonochemical Preparation Research Articles

The sonochemical approach improves the CuO–ZnO/TiO2 catalyst for WGS reaction

The CuO-ZnO composite was deposited onto two kinds of titania supports, which are synthetic mesoporous TiO2 and commercial TiO2 P25 (Degussa), via the ultrasound assisted precipitation and incipient wetness impregnation (IWI) methods, respectively. The catalysts were tested for WGS reaction in the temperature range of 200-400 °C, and the best catalytic performance was achieved for the sonochemically prepared catalysts supported on the commercial TiO2 P25, which contains well crystallized anatase and rutile phases. Although the synthetic mesoporous TiO2 has a higher surface area, its textural structure is not stable under the reaction conditions, leading to gradual deactivation of the CuO-ZnO/TiO2 catalyst. It is found that the sonochemical preparation offers at least two advantages: (1) generation of mesopores on the catalyst surface and (2) doping of ZnO into the CuO phase. The doping of ZnO, particularly in the case of commercial TiO2 P25, provides high activity and extra stability to the active phase of Cu(0). These new findings provide new insights into the design and development of better heterogeneous catalysts for WGS reaction.

Sonochemical preparation of carbon spheres

Spherical morphology of carbon with 150–400nm size is produced by sonication (480kHz, 2.5W) of toluene with water under ambient conditions. Medium range of frequency and weak power of ultrasound is found to be the appropriate conditions for preparing the carbon spheres. Morphological and structural analysis of the product is carried out with TEM, SEM, elemental analysis, TGA, and FT-IR spectroscopy.

A9 メソポーラスカーボンを担体とした燃料電池用白金触媒の超音波による調製(口頭発表)

A9 メソポーラスカーボンを担体とした燃料電池用白金触媒の超音波による調製(口頭発表)

Sonochemical preparation of pure t-LaVO4 nanoparticles with the aid of tris(acetylacetonato)lanthanum hydrate as a novel precursor

Herein a simple and fast method is introduced for the synthesis of lanthanum orthovanadate (LaVO4) nanoparticles under ultrasound irradiation. The effect of tris(acetylacetonato)lanthanum hydrate ([La(acac)3·3H2O]) and La(OAc)3 as two different precursors on the morphology and phase purity of LaVO4 was investigated. To optimum the particle size of the products, sonication time and the kind of surfactants have been changed. The as-synthesized products were characterized by XRD, FT-IR, SEM, TEM, and EDS. Based on the obtained results, it was found that the size and shape of the sonochemically formed LaVO4 nanoparticles were dramatically dependent on the sonication time, type of surfactant and lanthanum precursor. According to the XRD results, it was observed that pure tetragonal phase lanthanum orthovanadate (t-LaVO4) could be obtained only by using [La(acac)3·3H2O] as precursor under ultrasound irradiation for 30min. On the other hand, monoclinic phase lanthanum orthovanadate (m-LaVO4) with poor crystallinity has been produced by vigorous stirring at room temperature without sonication.

Graphite oxide-assisted sonochemical preparation of α-Bi2O3 nanosheets and their high-efficiency visible light photocatalytic activity

Novel α-Bi2O3 nanosheets have been successfully synthesized by graphite oxide (GO)-assisted sonochemical route and subsequent calcining treatment. The morphology of the final products can be controlled by tuning GO nanosheets in the synthesis process. Porous and nanosheet-covered α-Bi2O3 microrods have also been obtained, and the growth mechanism has been discussed. Scanning electron microscopy and transmission electron microscopy analyses reveal that the α-Bi2O3 nanosheets are 10–20 nm in thickness with suppressed growth along the [2 1 −4] direction. Owing to the unique structure, the α-Bi2O3 nanosheets show broader optical absorption and narrower band gap (2.25 eV) as compared to other two forms of α-Bi2O3 (~2.8 eV). Photocatalytic experiments demonstrated that the α-Bi2O3 nanosheets exhibited excellent activity much higher than the porous and nanosheet-covered α-Bi2O3 microrods in degrading organic pollutants under visible light. This study opens up a new route for the preparation of α-Bi2O3 nanosheets with superior photocatalytic performance.

Hydrothermal and sonochemical preparation and photocatalytic and bactericidal activities of ZnFe2O4–SnO2 nanocomposite

ZnFe2O4–SnO2 nanocomposite has been prepared by hydrothermal and sonochemical methods. Electron microscopic images reveal the composites as nanomaterials. X-ray diffractograms show cubic ZnFe2O4 and tetragonal SnO2 as the components of the composites. The energy dispersive X-ray spectra provide the composition of hydrothermally and sonochemically prepared composites as 71% (mol.) SnO2 and 29% (mol.) ZnFe2O4 and 14.4% (mol.) SnO2 and 85.6% (mol.) ZnFe2O4, respectively. Both the composites absorb visible light. The composites are ferromagnetic and the saturation magnetization of hydrothermally prepared nanocomposite is less than that of sonochemically obtained one. Visible light-photocatalytic activity of hydrothermally prepared nanocomposite is larger than that of the other. In addition, both the nanocomposites exhibit bactericidal activity. Hydrothermally prepared ZnFe2O4–SnO2 nanocomposite is a magnetically separable antibacterial visible light-photocatalyst and is a promising nanomaterial for environmental cleanup.

Sonochemical preparation and characterization of CeO2 nanoparticles using polyethylene glycols as a neutral surfactant

Nano-sized cerium oxide (CeO2) was synthesized successfully by a simple method using ultrasonic irradiation in the presence of polyethylene glycol (PEG 2000). X-ray diffraction, scanning electron microscope, and transmission electron microscope were used to characterize the structure and morphology of the synthesized powder. The nanocrystaline CeO2 was grown in a face-centered cubic. The average particle size of synthesized CeO2 is ~15 nm as revealed by the transmission electron microscopy investigations.

Sonochemical Preparation of Nano-TiO2 and Photocatalytic Degradation of Methylene Blue

Sonochemical Preparation of Nano-TiO2 and Photocatalytic Degradation of Methylene Blue

Sonochemical preparation of copper sulfides with different phases in aqueous solutions

There is a growing interest in the synthesis of nanostructured copper sulfides due to their ability to form compounds with various stoichiometries. We report a sonochemical route for the preparation of copper sulfides with different compositions in aqueous solutions, using different, general and convenient copper sources such as copper acetate, copper hydroxide or basic copper carbonate and thiourea or thioacetamide as sulfur precursors under ambient air. Phase analysis, purity and morphology of the products were studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results revealed that nanoparticles of covellite, CuS, with crystallite sizes between 7 and 18nm can be obtained by using different precursors and complexing agents and that chalcocite, Cu2S, can also be prepared sonochemically.

Ultrasound-promoted synthesis of pyrrolidin-2-ones in aqueous medium

Pyrrolidin-2-ones have received considerable attention due to their activity in CNS as nootropic drugs . In parallel, t he search for environmentally sustainable processes have been triggered the planning of actions related to organic synthesis. In this concern, the use of ultrasound to accelerate organic reactions has proven to be an important tool for meeting the goals of minimization of waste and reduction of energy requirements. In a previously published work, we have demonstrated the synthesis of several pyrrolidin-2-ones under classical conditions. Herein, we present the results of the green sonochemical preparation of a series of 1-(aryl)-5-(3,3,3-trifluoro-2-oxopropylidene)pyrrolidin-2-ones using water as an eco-friendly solvent in shorter reaction times. The target products ( 3a-h ) were obtained after sonication of methyl 4-methoxy-6-oxo-7,7,7-trifluoro-4-heptenoate ( 1 ) and anilines in the presence of triethylamine (TEA). Purification of products was performed by crystallization from hexano/EtOH.

Rapid sonochemical preparation of shape-selective lead iodide

Lead iodide (PbI2) films/crystals with various nano/micro morphologies (e.g., Nanoflake, block and microrod) were rapidly synthesized by taking advantage of a simple sonochemical method. The PbI2 crystals with uniform nanoflake structures could be fabricated directly on lead foils with the irradiation time as short as 36s via interfacial reaction between lead foils and elemental iodine in ethanol at ambient temperature. It was found experimentally that the morphologies of the resulting thin films/crystals could be well controlled by the adjustment of several parameters including irradiation time, reaction solvents, iodine concentration, ultrasonic power, and reaction temperature. Most importantly, the resultant PbI2 films are stable enough to resist rolling under the drastic ultrasound irradiation in a liquid media. This method is believed to be the fastest way for in situ fabrication of morphology-controlled semiconductor films on various metal substrates for subsequent applications related to the other metal iodide or metal sulfide semiconductor films.

Folic acid-functionalized human serum albumin nanocapsules for targeted drug delivery to chronically activated macrophages

Activated synovial macrophages play a key role in Rheumatoid Arthritis (RA). Recent studies have shown that folate receptor beta (FRβ) is specifically expressed by activated macrophages. Therefore a folate-based nanodevice would provide the possibility of delivering therapeutic agents to activated macrophages without affecting normal cells and tissues.This study shows for the first time the sonochemical preparation of HSA nanocapsules avoiding toxic cross linking chemicals and emulsifiers used in other methods.Production of HSA nanocapsules was optimized leading to a diameter of 443.5±9.0nm and a narrow size distribution indicated by a polydispersity index (PDI) of 0.066±0.080. Nanocapsules were surface modified with folic acid (FA) and the FA content was determined to be 0.38 and 6.42 molecules FA per molecule HSA, depending on the surplus of FA employed. Dynamic light scattering was used to determine size, PDI and zetapotential of the produced nanocapsules before and after surface modification. FA distribution on the surface of HSA nanocapsules was localized three-dimensionally after fluorescence labeling using confocal laser scanning microscopy (CLSM). Furthermore, specific binding and internalization of HSA nanocapsules by FRβ-positive and FRβ-negative macrophages, obtained from human peripheral blood mononuclear cells, was demonstrated by flow cytometry. FRβ-expressing macrophages showed an increased binding for FA-modified capsules compared with those without FA.

One-pot sonochemical preparation of fluorographene and selective tuning of its fluorine coverage

Fluorographene (FG), which inherits the properties of graphene and fluorographite (FGi), holds great promise for applications in high-performance materials and devices, including lubricants, nanocomposites, batteries, and nanoelectronics. However, challenges for realizing large-scale preparation and little knowledge concerning FG's physicochemical properties hinder its practical applications. Here, a novel and feasible method is developed to prepare FG through a simple sonochemical exfoliation process in N-methyl-2-pyrrolidone (NMP). Interestingly, FG at a high concentration in NMP displays dramatic stability without any additional stabilizer or modifier, and the C/F ratio of FG can be facilely tuned just by adjusting the sonochemical time. Furthermore, the electrochemical and thermal properties of the prepared FG have been systematically investigated and exhibited regularity with variation of fluorine coverage. On the other hand, based on the solubility of FG in various solvents, a possible dispersion mechanism is proposed to guide FG's further applications in films or polymer-based composites as a mechanical reinforcement.

Sonochemical synthesis of versatile hydrophilic magnetite nanoparticles

Hydrophilic magnetite nanoparticles in the size range 30–10nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH)2 in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7.Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too.Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character.The sonochemical preparation is easily scalable to meet industrial demand.

(Student Poster Award Winner) Sonochemical Preparation of PdCu as Oxygen Reduction NanoCatalyst for PEMFC

The sonochemical synthesis of PdCu is presented. The electrocatalyst was characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The XRD result shows evidence of the alloy nanoparticles with 8 nm in average size. SEM image shows regular spherical agglomerates between 50 and 200 nm in size. Its catalytic activity for the oxygen reduction reaction (ORR) was evaluated using cyclic voltammetry (CV) and rotating-disk electrode (RDE) in a 0.5 M H2SO4 electrolyte at 25 °C. Then the PdCu was tested as cathode in a PEMFC. The electrochemical activity and its performance in the PEM fuel cell were compared with the behavior of palladium. The bimetallic catalyst shows in both cases higher activity for the ORR than the Pd alone.

Sonochemical preparation of massive CrO 2 nanowires

One-dimensional (1D) nanostructures with precise controlled morphologies have not been easily accessible, usually degrading the device performance and therefore limiting applications to various advanced nanoscale magnetism. Generally bulk chromium dioxides are prepared by solid/liquid-phase reactions at elevated pressures or the chemical vapor deposition procedure whereas a liquid synthesis at non-pressure conditions, particularly for sonochemical one, has really been a challenge. Here we report on an ultrasound fabrication of large-scale CrO 2 nanowires by using CrO 2Cl 2 and homemade Cr 2O 3 hollow nanospheres for the first time. The as-synthesized products were characterized by X-ray diffraction/photoelectron spectroscopy, scanning/transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, selected area electron diffraction, and superconducting quantum interference devices magnetometer, respectively. The results show the controlled nanowires with diameter of 100–200 nm possess a single crystal tetragonal structure and exhibit a colossal coercive field (1678 Oe) at room-temperature, which could have potential applications in spin filtering, high density magnetic recording, and nanosensors. The proposed chemical reaction mechanism is suggested in detail and such a colossal coercive field is tentatively explained.

Sonochemical Preparation of Functionalized Graphenes

A convenient sonochemical method is described for the preparation of polystyrene functionalized graphenes starting from graphite flakes and a reactive monomer, styrene. Ultrasonic irradiation of graphite in styrene results in the mechanochemical exfoliation of graphite flakes to single-layer and few-layer graphene sheets combined with functionalization of the graphene with polystyrene chains. The polystyrene chains are formed from sonochemically initiated radical polymerization of styrene and can make up to ~18 wt % of the functionalized graphene, as determined by thermal gravimetric analysis. This one-step protocol can be generally applied to the functionalization of graphenes with other vinyl monomers for graphene-based composite materials.

Sonochemical Preparation of Silica Nanorods for Gene Delivery Using Single-Walled Carbon Nanotubes as Templates

Silica nanorods were fabricated with single-walled carbon nanotubes (SWCNTs) via ultrasound. The diameter of the resulting SWCNT-silica particles ranged from 60 to 70 nm. The morphology of this composite material was investigated via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The individual SWCNTs are uniformly coated with silica and formed a unique nanocomposite material. The important role of ultrasound and the mechanism of silica layer formation on SWCNTs were explained via the hydrolysis of the silica source and the adsorption of the siloxane groups on the SWCNT surfaces under ultrasound irradiation. The amino-functionalized silica nanorods were demonstrated as non-viral vectors for gene delivery.

Sonochemical Preparation of Hierarchical ZnO Hollow Spheres for Efficient Dye‐Sensitized Solar Cells

Hierarchical ZnO hollow spheres (400-500 nm in diameter) consisting of ZnO nanoparticles with a diameter of approximately 15 nm have been successfully prepared by a facile and rapid sonochemical process. The formation of hierarchical ZnO hollow spheres is attributed to the oriented attachment and subsequent Ostwald ripening process according to time-dependent experiments. The as-prepared ZnO hollow spheres are used as a photoanode in dye-sensitized solar cells and exhibit a highly efficient power conversion efficiency of 4.33%, with a short-circuit current density of 9.56 mA cm(-2), an open-circuit voltage of 730 mV, and a fill factor of 0.62 under AM 1.5 G one sun (100 mW cm(-2)) illumination. Moreover, the photovoltaic performance (4.33%) using the hierarchical ZnO hollow spheres is 38.8% better than that of a ZnO nanoparticle photoelectrode (3.12%), which is mainly attributed to the efficient light scattering for the former.

Sono-chemical preparation of cellulose nanocrystals from lignocellulose derived materials

This study examined the production of cellulose nanocrystals from microcrystalline wood cellulose, Avicel and recycled pulp of wood pulp using sono-chemical-assisted hydrolysis. Two hydrolysis systems: deionized water and maleic acid were evaluated. In deionized water, Avicel produced cellulose nanocrystals with average diameter of 21 ± 5 nm (minimum 15 nm and maximum 32 nm). Cellulose nanocrystals from recycled pulp were not distinctively spherical and had an average diameter of 23 ± 4 nm (minimum 14 nm and maximum 32 nm). Maleic acid (50 mM) sono-chemical assisted hydrolysis of Avicel at 15 °C and 90% power output for 9 min produced cellulose nanocrystals which were cylindrical in shape and were of dimensions, length 65 ± 19 nm and width 15 nm.