Synthesis of copper dendrite nanostructures by a sonoelectrochemical method

Copper dendrites have been prepared by a sonoelectrochemical process from an aqueous solution of Cu(2+) in the presence of polyvinyl alcohol. A SEM image of the morpholohy of the copper formed on the electrode after one electric pulse is presented. A subsequent sonic pulse removes the copper from the electrode surface, cleaning it for the next step. The formation of the dendrites is accounted for by the "drying-mediated self-assembly of nanoparticles" theory.     

Synthesis and characterization of one-dimensional CdSe by a novel reverse micelle assisted hydrothermal method

Nanocrystalline cadmium selenide (CdSe) is a low bandgap material (E(g)=1.75 eV, at room temperature) with potential applications in photoelectronic devices. Its electronic properties are dependent on the dimensions of the crystals. In this study, one-dimensional wurtzite CdSe nanoparticles with a diameter of 43+/-6 nm and an aspect ratio of 3.7+/-0.6 were synthesized through a novel reverse micelle assisted hydrothermal method at a relatively low temperature. This method combines the advantages of the hydrothermal method's ability to achieve good crystallinity with the well-controlled growth offered by the reverse micelle method. The morphology of the nanoparticles can be controlled by the amount of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), the amount of hydrazine hydrate and the reaction temperature. It is proposed that AOT controls the length while hydrazine hydrate controls the diameter of the growing nanocrystals. The photoluminescence (PL) of individual nanorods and the longitudinal-optical phonon properties were mapped using confocal microscopy. Raman spectroscopy showed a blue-shift of both the LO and 2LO phonon peaks which may be due to a lattice contraction of the CdSe nanorods. A nucleation and growth mechanism for these nanoparticles is also proposed based on time-dependent studies.     

Preparation and characterization of a novel zeolite using hydrothermal synthesis in a stirred reactor

This paper describes the preparation of novel zeolite particles by the hydrothermal method in a stirred reactor. The variations between certain properties of the resulting zeolites, such as morphology by the scanning electron microscopy (SEM), pore properties (i.e., surface areas, pore volume, and porosity) by the surface area & porosity analyzer, crystallinity by the X-ray diffraction (XRD) and Si/Al ratio by the inductively coupled plasma-atomic absorption spectrometer (ICP-AES), and the process parameters, such as aging time, agitation speed, temperature and pressure, were studied at a specific gel composition. The optimal value of the Brunauer–Emmett–Teller (BET) surface area was found to be over 400 m²/g in the resulting microporous zeolite, indicating that the size was centered on about 0.5 nm. The XRD image was indicative of the probable formation of zeolite-P2 in the hydrothermal synthesis.     

Fabrication of hollow silica microspheres utilizing a hydrothermal approach

Hollow silica microspheres(HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor.The resulting silica hollow particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and infrared spectroscopy(IR).The surface area was determined using the BET method.SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5μm.     

Preparation and characterization of tamarind nut powder with in situ generated copper nanoparticles using one-step hydrothermal method

Tamarind nut powder (TNP) from kitchen waste of tamarind nuts was modified with in situ generated copper nanoparticles (CuNPs) using hydrothermal method. The modified TNP had spherical CuNPs with an average size of 84?nm. The thermal stability of the modified TNP was lower than that of the TNP due to the catalytic activity of the in situ generated CuNPs in lowering the thermal stability. Further, it exhibited significant antibacterial activity against both the Gram negative and Gram positive bacteria and hence can be used as low-cost filler to prepare antibacterial hybrid polymer nanocomposites for packaging and medical applications.     

The gas sensing properties of TiO_2 nanotubes synthesized by hydrothermal method

In this paper,the TiO₂ nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）. scanning electron microscope（SEM） and Brunauer-Emmett-Teller（BET）.The prepared TiO₂ nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested.Results show the prepared TiO₂ nanotube gas sensors responses to ethanol under dry condition at 450℃.This could be attributed to the fact that it had high porous morphology and a higher pore volume,which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover,the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H₂,CO,acetone.     

High-pressure Raman scattering on Fe2(MoO4)3 microcrystals obtained by a hydrothermal method

This study reports on the effect of high hydrostatic pressure on the vibrational spectra of Fe₂(MoO₄)₃ microcrystals using Raman scattering in combination with a membrane diamond-anvil cell. The ferric molybdate was obtained by the conventional hydrothermal method, and the structural and morphological properties of the sample were characterized using additionally X-ray diffraction, scanning electron microscopy, as well as energy dispersive spectroscopy. The X-ray diffraction measurements have shown that the crystals have a monoclinic structure. At pressures higher than 4.8 GPa, the disappearance of external modes was observed, suggesting that pressure has induced a breakdown in the translational symmetry of the crystal system. The high-pressure amorphous phase is reversible and attributed to an incomplete crystal-amorphous transformation.     

水热合成一锅法制备FePO4-SBA-15及其水热稳定性能

通过两种水热处理方式,即800 oC水汽条件和100 oC沸水处理,考察了一锅法制备的FePO4–SBA-15(OP)的水热稳定性.水热处理前后样品的结构变化通过小角X射线衍射和N2物理吸附表征.研究发现,经水热条件下原位生成FePO4修饰后的OP样品具有良好的水热稳定性,并且FePO4的担载量(5%和40%)对OP样品的水热稳定性几乎没有影响.这与文献报道的金属担载量会影响介孔材料水热稳定性的结果不同.此外,还对比研究了浸渍法制备的FePO4/SBA-15(IMP)和商品SBA-15的水热稳定性.结果表明,各样品水热稳定性由强到弱的顺序是OP>IMP>>SBA-15. OP和IMP样品水热稳定性优于纯硅分子筛SBA-15的原因可能是FePO4保护层能抑制介孔材料在水热环境下的结构塌陷. OP样品水热稳定性较IMP样品好的原因可能主要是由于OP样品中存在稳定的Si–O–Fe键和较多的微孔.     

水热合成一锅法制备FePO4-SBA-15及其水热稳定性能

通过两种水热处理方式，即800 oC水汽条件和100 oC沸水处理，考察了一锅法制备的FePO4–SBA-15(OP)的水热稳定性.水热处理前后样品的结构变化通过小角X射线衍射和N2物理吸附表征.研究发现，经水热条件下原位生成FePO4修饰后的OP样品具有良好的水热稳定性，并且FePO4的担载量(5%和40%)对OP样品的水热稳定性几乎没有影响.这与文献报道的金属担载量会影响介孔材料水热稳定性的结果不同.此外，还对比研究了浸渍法制备的FePO4/SBA-15(IMP)和商品SBA-15的水热稳定性.结果表明，各样品水热稳定性由强到弱的顺序是OP>IMP>>SBA-15. OP和IMP样品水热稳定性优于纯硅分子筛SBA-15的原因可能是FePO4保护层能抑制介孔材料在水热环境下的结构塌陷. OP样品水热稳定性较IMP样品好的原因可能主要是由于OP样品中存在稳定的Si–O–Fe键和较多的微孔.     

Controlled hydrothermal synthesis and growth mechanism of various nanostructured films of copper and silver tellurides

Various nanostructured films of copper and silver tellurides were hydrothermally grown on the corresponding metal substrates through reactions between metal foils and tellurium powder in different media. Interesting morphologies including nanowires, nanorods, nanobelts, nanosheets, and hierarchical dendrites were obtained. The nanostructured films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). A growth mechanism was proposed based on the characterization results. This study provides a low-temperature, solution-phase approach to grow low-dimensional, nanostructured metal tellurides with controllable morphologies.     

Lead zirconate titanate (PZT) films deposited by a hydrothermal method

We present a hydrothermal method to deposit PZT films. It uses a single-step hydrothermal process and user-friendly precursors. Pb(Zr_0.52,Ti_0.48)O₃ polycrystalline films, 5–10 μm thick, were produced in an aqueous basic solution (4M KOH) on a titanium substrate in a closed autoclave at 180 °C. A time-depending study to see the evolution of the films' formation is described. Some actuation testing is also presented.     

Investigation of the growth parameters of hydrothermal ZnO nanowires for scale up applications

Zinc oxide nano-wires (ZnO NWs) are synthesized reproducibly with high yield via a low temperature hydrothermal technique. The influence of the growth duration time, growth temperature, zinc precursor and base concentration of Na₂CO₃ on the morphology of NWs is investigated. The growth products are characterised using scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). SEM analysis shows that the optimum growth temperature is 140 °C and finds that length and diameter of ZnO NWs have a relationship with growth duration time and base concentrations of Na₂CO₃. In addition, it is reported that a high (～90%) yield of ZnO NWs can be synthesised via using any of three different precursors: zinc chloride, zinc acetate and zinc nitrate. TEM and XRD results indicate the high purity and the single crystalline nature of the ZnO NWs. XPS confirms the absence of sodium contaminants on the surface and indicates a near flat band surface condition. PL shows a large visible band in the yellow part of the spectrum, and a small exciton emission peak, indicating a large defect concentration, which is reduced after annealing in air.     

Electropolymerized coatings of polyaniline on copper by using the galvanostatic method and their corrosion protection performance in HCl medium

The synthesis of polyaniline coatings on the copper (Cu) surface has been investigated by using the galvanostatic method. The synthesized coatings were characterized by Fourier transform infrared spectroscopy, UV–visible absorption spectrometry and scanning electron microscopy. The anticorrosion performances of polyaniline coatings were investigated in 0.5 M HCl medium by the potentiodynamic polarization technique and electrochemical impedance spectroscopy. The corrosion rate of polyaniline‐coated Cu was found to be ～27 times lower than bare Cu, and potential corrosion increased from ?0.21 V versus Ag/AgCl for uncoated Cu to ?0.19 V versus Ag/AgCl for polyaniline‐coated Cu electrodes. Electrochemical measurements indicate that polyaniline coating has good inhibiting properties with a mean efficiency of ~96% at 10 mAcm^?2 current density applied on Cu corrosion in acid media. The results of this study clearly ascertain that the polyaniline has an outstanding potential to protect Cu against corrosion in an acidic environment. Copyright © 2014 John Wiley & Sons, Ltd.     

Controlled crystal phase and particle size of loaded-TiO2 using clinoptilolite as support via hydrothermal method for degradation of crystal violet dye in aqueous solution

TiO₂-supported clinoptilolites (TiO₂/clinoptilolites) were successfully synthesized with controlled crystal phase and particle size via hydrothermal method to enhance photocatalytic performance of TiO₂. The effects of various parameters including temperature, acidity and concentration of Ti-containing solutions on the particle size, crystal phase and agglomeration of TiO₂ supported on clinoptilolite were investigated thoroughly by characterizations of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), BET isotherm, UV–visible (UV–vis) spectrophotometer and Malvern zetasizer. The results demonstrate that increasing temperature and strengthen acidity are beneficial to enhance the crystallinity and particle size of supported TiO₂. Increase in acidity also leads to more uniform distribution of TiO₂ on the surface of clinoptilolite. The TiO₂ nano-crystals deposited on the surface of clinoptilolite, exhibit rutile or anatase phase, strongly depending on the preparation procedure. The resultant TiO₂/clinoptilolites could be used as photo-catalysts for the degradation of crystal violet (CV) dye in aqueous solution, showing a higher photo-catalytic activity with 89% degradation within 100 min. The effect of operational parameters, such as pH values of reaction media, dose of used catalyst, and concentration of CV dye on the CV degradation performance were investigated, in which the kinetics of CV dye degradation was found to follow the pseudo-first order kinetic model.     

Effects of pH and temperature on photocatalytic activity of PbTiO3 synthesized by hydrothermal method

PbTiO₃ photocatalyst was synthesized successfully by facile hydrothermal method. The effects of the hydrothermal reaction temperatures and the pH values of the systems on the photocatalytic activities of PbTiO₃ were investigated in detail. The photocatalytic activities of samples were evaluated by the degradation of methyl orange (MO) aqueous solution under simulated solar irradiation. The as-obtained PbTiO₃ sample exhibits anisotropical growth along the (0 0 1) plane, and its photocatalytic activity is about 3 times higher than that of PbTiO₃ prepared by precipitation method. Moreover, the as-prepared PbTiO₃ has high stability during photocatalytic oxidation process, and does not cause secondary pollution.     

Mercury selenide nanorods: Synthesis and characterization via a simple hydrothermal method

HgSe nanorods have been synthesized through a simple hydrothermal reduction approach. The nanorods formed were ≈45 nm average diameter and ≈3 μm nm in length. X-ray diffraction characterization suggested that the product consists of cubic phase pure HgSe. The as-prepared products were also characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). An X-ray energy dispersive spectroscopy (EDX) study further confirmed the composition and purity of the product. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. The results showed that the capping agent CTAB (cetyltrimethylammoniumbromide) plays a crucial role in the process. Other factors, such as the reaction time, temperature, different capping agent and the reductant type also have an influence on the morphology of the final products to some extent.     

Preparation and properties of low-cost cotton nanocomposite fabrics with in situ-generated copper nanoparticles by simple hydrothermal method

In this work, copper nanoparticles were in situ generated in cotton fabrics by simple hydrothermal method. These low-cost nanocomposite fabrics were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetric analysis, and antibacterial tests. The presence of spherical nanoparticles was visualized by SEM analysis. FTIR spectra did not show any differences between the peak positions of cotton fabrics and their nanocomposites. The crystallinity of cotton nanocomposites was enhanced by the copper nanoparticles. The cotton nanocomposite fabrics exhibited good antibacterial activity against Escherichia coli bacteria and hence can be considered for medical applications such as wound dressing, surgical aprons, hospital bed materials, etc.     

Preparation and characterization of gadolinium hydroxide single-crystalline nanorods by a hydrothermal process

The Gd(OH)3 nanorods with diameters of ca.40-60 nm and lengths of more than 400-550 nm have been prepared by a novelhydrothermal technique.The structural features and chemical composition of the nanorods were investigated by X-ray diffraction(XRD),transmission electron microscopy(TEM),and field emission scanning electron microscope(FESEM),selected areaelectron diffraction(SAED),and high resolution transmission electron microscopy(HRTEM).The possible mechanism for theformation of Gd(OH)3 nanorods was proposed.     

Synthesis of α-SnWO4 thin-film electrodes by hydrothermal conversion from crystalline WO3

Thin film electrodes of the orthorhombic form of tin tungstate (α-SnWO4) were prepared using a hydrothermal method to convert thin films of WO3 in aqueous SnCl2. The pH dependence of the growth mechanism was identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD patterns show complete conversion of WO3(s) to SnWO4(s) at pH 1, 4, and 7. SEM images reveal a morphology change from sponge-like platelets to sharp nanowires as the pH increases from 1 to 7. The α-SnWO4 thin films were reddish brown in color, and display an indirect band gap of 1.9 eV by diffuse reflectance UV-vis spectroscopy. α-SnWO4 is therefore solar-responsive, and a chopped light linear sweep voltammogram recorded under 100 mW/cm2 AM1.5 simulated solar illumination in a pH 5 0.1 mol/L KPi buffer show a visible light response for photoelectrochemical water oxidation, producing 32 mA/cm2 at 1.23 V vs. RHE.     

电重法测定混合铜矿中自由氧化铜的方法研究

本方法用于混合铜矿石中自由氧化铜的测定。试样用含0.6%（m/v）亚硫酸钠的10%(v/v)硫酸溶液浸取两小时,选择性溶解铜氧化物,过滤并煮沸滤液,用去离子水稀释后电解。溶液中的铜离子电积至阴极铂网上。用火焰原子吸收分光光度法检测残余于电解后液中的铜离子;同时用1 1硝酸溶解铂网上的铜,并用火焰原子吸收分光光度法检测与阴极铜共电积的杂质元素含量,用铂阴极差重加上电积后液残余铜含量并减去共电积的杂质元素含量可计算出氧化铜矿中酸溶铜含量。此方法相比国标碘量法,用肉眼观察颜色变化确定终点,人为误差小,结果稳定、准确。通过对加拿大氧化铜矿标准物质AMIS0050进行测定(n=12),方法准确度可靠。并选取十五批次的氧化铜矿检测,与经典碘量法比对,结果令人满意。