Sonochemical synthesis of CuO nanostructures and their morphology dependent optical and visible light driven photocatalytic properties

A controlled synthesis of CuO nanostructures with various morphologies were successfully achieved by presence/absence of low frequency (42 kHz) ultrasound with two different methods. The size, shape and morphology of the CuO nanostructures were tailored by altering the ultrasound, mode of addition and solvent medium. The crystalline structure and molecular vibrational modes of the prepared nanostructures were analysed through X-ray diffraction and FTIR measurement, respectively which confirmed that the nanostructures were phase pure high-quality CuO with monoclinic crystal structure. The morphological evaluation and elemental composition analysis were done using TEM and EDS attached with SEM, respectively. Furthermore, we demonstrated that the prepared CuO nanostructures could be served as an effective photocatalyst towards the degradation of methyl orange (MO) under visible light irradiation. Among the various nanostructures, the spherical shape CuO nanostructures were found to have the better catalytic activities towards MO dye degradation. The catalytic degradation performance of MO in the presence of CuO nanostructures showed the following order: spherical\nanorod \layered oval \nanoleaf \triangular \shuttles structures. The influence of loading and reusability of catalyst revealed that the efficiency of visible light assisted degradation of MO was effectively enhanced and more than 95 % of degradation was achieved after 3 cycles

Hydrothermal synthesis and photoluminescent properties of stacked indium sulfide superstructures

Unusual hierarchical stacked superstructures of cubic beta-In2S3 were fabricated via a facile hydrothermal process in the presence of a surfactant cetyltrimethylammonium bromide CTAB; the 3D superstructures were developed by helical propagation of surface steps from microflakes of 10-20 nm thickness.

Synthesis, characterization and assembly of BiOCl nanostructure and their photocatalytic properties

In this article, a two-dimensional (2D) nanoplate and a 3D hierarchical structure of BiOCl were synthesized through a simple sonochemical route. Compared with previous preparation methods, the 2D nanoplates can be prepared at a relatively short time (about 30 min) with low energy used. Additionally, these 2D nanoplates can easily assemble into a 3D hierarchical structure with the surfactant reagents. The obtained products were well crystallized and subsequently characterized by a range of methods, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission microscopy (HRTEM), selected area electron diffraction (SAED) and Raman spectroscopy.

Spindle-like Lanthanide Orthovanadate Nanoparticles: Facile Synthesis by Ultrasonic Irradiation, Characterization, and Luminescent Properties

A general and facile ultrasonic irradiation method has been established for the synthesis of the lanthanide orthovanadate LnVO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) nanoparticles from an aqueous solution of Ln(NO3)(3) and NH4VO3 without any surfactant or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the as-prepared products. Ultrasonic irradiation has a strong effect on the morphology of the LnVO(4) nanoparticles. The SEM and TEEM images illustrate that the as-formed LnVO(4) particles have a spindle-like shape with an equatorial diameter of 30-70 nm and a length of 100-200 am, which are the aggregates of even.

Selective synthesis of mesoporous and nanorod CeVO4 without template

A simple and efficient method has been established for the selective synthesis of mesoporous and nanorod CeVO4 with different precursors by sonochemical method. CeVO4 nanorod can be simply synthesized by ultrasound irradiation of Ce(NO3)(3) and NH4VO3 in aqueous solution without any surfactant or template. While mesoporous CeVO4 with high specific surface area can be prepared with Ce(NO3)(3), V2O5 and NaOH in the same way. Mesoporous CeVO4 has a specific surface area of 122 m(2) g(-1) and an average pore size of 5.2 nm; CeVO4 nanorods have a diameter of about 5 nm, and a length of 100-150 nm. The ultrasound irradiation and ammonia in the reactive solution are two key factors in the formation of such rod-like products. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and differential thermal analyses (DTA), UV/vis absorption spectroscopy and Brunauer-Emmett-Teller (BET) were applied for characterization of the as-prepared products.

Synthesis and characterization of stable Co and Cd doped nickel hydroxide nanoparticles for electrochemical applications

The present paper describes the physical-chemical characterization and electrochemical behavior of a new nanomaterial formed by the addition of cadmium and cobalt atoms into the structure of nickel hydroxide nanoparticles, these ones synthesized by an easy sonochemical method. Particles of about 5 nm diameter were obtained and characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy. Different nickel hydroxide nanoparticles were immobilized onto transparent conducting substrates by using electrostatic layer-by-layer providing thin films at the nanoscale and the electrochemical behavior was investigated. The formation of a mixed hydroxide was corroborated by observation of very interesting properties as redox potential shifting to less positive potentials and high stability when submitted to long electrochemical cycling or high times of ultrasonic synthesis, suggesting practical applications. (C) 2008 Elsevier B.V. All rights reserved.

Ultrasound promoted greener synthesis of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles

A rapid and cleaner procedure for the synthesis of a series of 2-(3,5-diaryl-45-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles under ultrasonic irradiation in ethanol is described. (C) 2010 Elsevier B.V. All rights reserved.

A novel route to the synthesis of mesoporous Titania with full anatase nanocrystalline domains

A porous, high surface area TiO2 with anatase or rutile crystalline domains is advantageous for high efficiency photonic devices. Here, we report a new route to the synthesis of mesoporous titania with full anatase crystalline domains. This route involves the preparation of anatase nanocrystalline seed suspensions as the titania precursor and a block copolymer surfactant, Pluronic P123 as the template for the hydrothermal self-assembly process. A large pore (7 - 8 nm) mesoporous titania with a high surface area of 106 - 150 m(2)/g after calcination at 400degreesC for 4 h in air is achieved. Increasing the hydrothermal temperature decreases the surface area and creates larger pores. Characteristics of the seed precursors as well as the resultant mesoporous titania powder were studied using XRD analysis, N-2-adsorption/desorption analysis, and TEM. We believe these materials will be especially useful for photoelectrochemical solar cell and photocatalysis applications.

Exploiting oriented attachment in stabilizing La3+-doped gallium oxide nano-spindles

Retaining the morphology of gallium oxide nanostructures during structural transformations or after doping with lanthanide ions is not facile. Here we report on the sonochemical synthesis of nearly monodisperse similar to 550 nm long nano-spindles of undoped and La-doped alpha-GaOOH. The transformation of as-prepared undoped and La-doped alpha-GaOOH powders into the corresponding undoped and La-doped Ga2O3 phases (alpha and beta) was achieved by carrying out controlled annealing at elevated temperatures under optimized conditions. The formation of gallium oxide nano-spindles is explained by invoking the phenomenon of oriented attachment, as amply supported by electron microscopy. Interestingly, the morphology of the gallium oxide nano-spindles remained conserved even after doping them with more than 1.4 at% of La3+ ions. Such robust structural stability could be attributed to the oriented attachment-type growth observed in the nano-spindles. The as-prepared samples and the corresponding annealed ones were thoroughly characterized by powder X-ray diffraction (PXRD), electron microscopy (SEM, TEM, and STEM-EDS) and X-ray photoelectron spectroscopy (XPS). Finally, photoluminescence from the single-crystalline undoped and La-doped beta-Ga2O3 was explored.

超声化学法合成稀土纳米材料

稀土纳米材料因其独特的光、电、磁和催化等性能，在纳米器件和功能材料等诸多领域具有重要的应用价值。大量研究表明，纳米材料的物理和化学性质与其尺寸、成分、形貌和晶型密切相关。稀土纳米材料的合成方法有许多，然而，要真正实现这类材料的简单可控合成仍然是个艰难的课题。超声化学法由于具有操作简单、合成周期短、反应温度低、成本低廉并且产物均匀、粒径分布窄和纯度高等突出优点，已经在无机纳米材料制备领域中显示出独特的魅力。因此，本论文的工作是运用超声化学法合成有广泛应用前景的稀土纳米材料，对产物的形貌和粒径进行有效的调控，研究和分析其形成机理，并进一步考察其形貌、结构与性能之间的相互关系。 在本论文中，我们研究的体系集中在稀土磷酸盐、稀土氟化物和稀土钒酸盐三类纳米材料。 采用超声化学法得到的CePO4:Tb和CePO4:Tb/LaPO4(核/壳)纳米棒结晶完好，具有CePO4体材料的六方相结构。CePO4:Tb纳米棒直径为10-30 nm，长度为200 nm，CePO4:Tb/LaPO4(核/壳)纳米棒的LaPO4壳的厚度为2-10 nm。CePO4:Tb和CePO4:Tb/LaPO4(核/壳)纳米棒均具有Ce3+ (5d - 4f)和Tb3+ 5D4-7FJ(J = 6-3)的特征发射。与CePO4:Tb纳米棒核相比，CePO4:Tb/LaPO4(核/壳)纳米棒的光谱强度及荧光寿命均有较大的提高，这是由于形成核/壳结构后发光中心镧系金属离子与表面淬灭中心的距离增大，减少了能量传递过程中非辐射复合的路径，使能量淬灭受到抑制。 采用简单、快速、无模板辅助的超声化学法合成了稀土氟化物，并对产物的形貌和粒径进行了有效的调控。通过应用不同氟源(KBF4、NaF和NH4F)选择性合成了具有不同形貌的CeF3纳米材料，如片状、棒状和颗粒状。对具有不同形貌的CeF3样品进行了UV-Vis吸收光谱和荧光光谱测试和比较。研究结果表明不同形貌的样品，它们的光学性质存在很大差异，这说明纳米材料的光学性质与其形貌、粒径、晶体结构等因素有密切的关系。得到的EuF3单晶纳米材料具有三维花状形貌。这些纳米花的外形为球状，平均直径为0.9 μm-1.0 μm，每个花瓣的厚度约为0.14 μm。在其他实验条件不变的情况下，采用搅拌法而不经过超声辐射的对比实验只能得到二维纳米片，这表明超声辐射对花状EuF3的形成起到了至关重要的作用。基于不同反应时间的实验结果，我们提出了这种三维花状EuF3纳米材料可能的形成机理。 采用超声化学法选择性地合成了介孔及棒状CeVO4和纺锤状的YVO4:Eu3+ 纳米材料。CeVO4纳米棒的平均直径为5 nm，长度为150 nm。介孔CeVO4材料的比表面积较高(122 m2•g-1)，孔径分布窄，其催化性能有望得到提高。纺锤状的YVO4:Eu3+ 纳米粒子具有四方相锆石结构，其直径为90-150 nm，长度为250-300 nm。超声辐射对样品的形貌起着关键作用，在其他反应条件不变，未采用超声辐射的情况下只能得到团聚严重的纳米颗粒。荧光测试表明，纺锤状YVO4:Eu样品表现为Eu3+ 5D0-7FJ(J = 1- 4)的特征跃迁，以5D0-7F2电偶极跃迁(614nm)为最强峰，属于红光发射。

Morphological control and luminescent properties of CeF3 nanocrystals

The nanocrystals of CeF3 with the hexagonal structure and different morphologies such as the disk, the rod, and the dot have been successfully synthesized via a mild ultrasound assisted route from an aqueous solution of cerium nitrate and different fluorine sources (KBF4, NaF, NH4F). The use of different fluorine sources has a remarkable effect on the morphology of the final product. The luminescence and UV-vis absorption properties of CeF3 nanocrystals with different morphologies have been investigated. Compared with other shape nanocrystals, the luminescence intensity of the disklike nanocrystals is obviously enhanced. It is suggested that the function-improved materials could be obtained by tailoring the shape of the CeF3 nanocrystals.

Processamento sonoquímico de materiais mesoestruturados de óxido de zinco dopados com terras-raras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sonochemical Acceleration of Conversion of 2-Alkoxytetrahydrofurans to y-Butyrolactones Synthesis of (±)-Quercus Lactone-A

Effect of sonochemical irradiation on the conversion of 2-alkoxytetrahydrofurans to γ-butyro-1actores by Jones reagent, and its extension to the highly stereoselective synthesis of quercus lactone a, is reported.

Synthesis of highly efficient and recyclable visible-light responsive mesoporous g-C3N4 photocatalyst via facile template-free sonochemical route

Herein we demonstrate a facile template-free sonochemical strategy to synthesize mesoporous g-C3N4 with a high surface area and enhanced photocatalytic activity. The TEM and nitrogen adsorption–desorption studies confirm mesoporous structure in g-C3N4 body. The photocatalytic activity of mesoporous g-C3N4 is almost 5.5 times higher than that of bulk g-C3N4 under visible-light irradiation. The high photocatalytic performance of the mesoporous g-C3N4 was attributed to the much higher specific surface area, efficient adsorption ability and the unique interfacial mesoporous structure which can favour the absorption of light and separation of photoinduced electron–hole pairs more effectively. A possible photocatalytic mechanism was discussed by the radicals and holes trapping experiments. Interestingly, the synthesized mesoporous g-C3N4 possesses high reusability. Hence the mesoporous g-C3N4 can be a promising photocatalytic material for practical applications in water splitting as well as environmental remediation.

Synthesis and photoluminescent properties of silica-coated LaCeF3 : Tb nanocrystals

La0.45Ce0.45F3:Tb (10 mol% Tb) nanoparticles was synthesized via sonochemical method and then coated with silica (SiO2) shells through a microemulsion process, resulting in the formation of core/shell structured LaCeF3:Tb/SiO2 nanoparticles. The obtained core/shell LaCeF3:Tb/SiO2 nanoparticles are spherical and uniform in size (average size about 60 nm), strongly fluorescent, and long fluorescence lifetime (1.87 ms). This kind of nanoparticles was water-soluble, which could be applied in biological labeling and other fields.