Synthesis and optical properties of SnO(2) nanorods

Well-crystalline SnO(2) nanorods have been synthesized successfully via a lithium-assisted solution-phase method. The structural and optical properties of the SnO(2) nanorods were investigated using x-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and infrared, Raman and photoluminescence spectroscopy. The experimental results show that lithium addition plays a critical role in the formation of SnO(2) nanorods, and the correlation between the surface energy change and morphological evolution of this material is also discussed. This approach provides an economically viable route for large-scale synthesis of this nanostructured material.     

Facile sonochemical synthesis of CePO(4):Tb/LaPO(4) core/shell nanorods with highly improved photoluminescent properties

A simple, efficient and quick method has been established for the synthesis of CePO(4):Tb nanorods and CePO(4):Tb/LaPO(4) core/shell nanorods via ultrasound irradiation of inorganic salt aqueous solution under ambient conditions for 2?h. The as-prepared products were characterized by means of powder x-ray diffraction (PXRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra and lifetimes. TEM micrographs show that all of the as-prepared cerium phosphate products have rod-like shape, and have a relatively high degree of crystallinity and uniformity. HRTEM micrographs and SAED results prove that these nanorods are single crystalline in nature. The emission intensity and lifetime of the CePO(4):Tb/LaPO(4) core/shell nanorods increased significantly with respect to those of CePO(4):Tb core nanorods under the same conditions. A substantial reduction in reaction time as well as reaction temperature is observed compared with the hydrothermal process.     

High-quality single-walled carbon nanotubes synthesis by hot filament CVD on Ru nanoparticle catalyst

We investigated the single-walled carbon nanotubes (SWCNTs) growth on Ru nanoparticle catalyst via hot filament assisted chemical vapor deposition (HFCVD) with two independent W filaments for the carbon precursor (methane) and the hydrogen dissociation respectively. The Ru nanoparticles were obtained following a two-step strategy. At first the growth substrate is functionalized by silanisation, then a self assembly of a ruthenium porphyrin complex monolayer on pyridine-functionalized metal oxide substrates. We have studied the impact of the filaments power and we optimized the SWCNTs growth temperature. The as grown SWCNTs were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. It was found that the quality, density and the diameter of SWCNTs depends on the filament and growth temperature. Results of this study can be used to improve the understanding of the growth of SWCNTs by HFCVD.     

Li electroactivity of iron (II) tungstate nanorods

We herein report the first application of a divalent iron tungstate (FeWO(4)) nanostructured material, with a wolframite structure, to a Li-ion battery anode. The FeWO(4) nanospheres and nanorods were synthesized at 180?°C without any surfactants or templates via a facile hydrothermal process by simply adjusting the pH. The resulting nanopowders were characterized using x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller (BET) measurements. Furthermore, we evaluated the Li electroactivity of the FeWO(4) nanorods using cyclic voltammetry and observed that their reversible capacity was over 500 mAh g(-1) after 20 cycles, which proved much higher than that of graphite-based anodes.     

Morphological transformations induced by Co impurity in ZnO nanostructures prepared by rf-sputtering and their physical properties

Growth of uniform and vertically well aligned nanorods is a difficult process and becomes more complicated in case of ZnO nanorods on silicon (Si) substrate due to thermal instability of the Si substrate and large lattice mismatch (~?40%) between the substrate and the ZnO nanorods array. Growth of ZnO nanorods assisted by metal ion via rf-sputtering is a good technique; however, it needs many parameters to be controlled for desired growth and morphology of nanostructures. In this work, we report the morphological transformations of ZnO nanostructured thin film by simply controlling the concentration of Cobalt (Co) impurity in sputtering target. With the introduction of Co ions in ZnO matrix, the initial coalescence grain structure (pyramidal morphology) changes into columnar grains and as the concentration of Co ions increases further, a highly oriented ZnO nanorods array is obtained. The possible mechanism with the help of schematic diagram is also proposed for the morphological transformation of ZnO nanostructures. The vertically aligned nanorods show good optical properties as well as robust ferromagnetism at room temperatures. It has also been observed that with the dopant conc. increasing there was a significant decrease in the band gap energy. The structure and morphology of rf-sputtered nanostructured thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and selected area electron diffraction. Interestingly, with Co conc. increasing in ZnO matrix results in decreasing LO modes in Raman spectroscopy. It can have strong influence on the magnetic properties of the material. The good optical and strong ferromagnetic properties of the ZnO nanorods, suggest its possible applications in the fields of lasers, spintronics and medical applications.     

Vertically aligned Fe-doped ZnO nanorod arrays by ultrasonic irradiation and their photoluminescence properties

A facile sonochemical route was demonstrated for the direct fabrication of Fe-doped ZnO nanorod arrays on a Si substrate under ambient conditions. By adding Fe³⁺ ions in reaction solution, Fe is readily in situ doped into ZnO nanorod arrays via ultrasound irradiation. The morphology and structural characteristic of the Fe-doped ZnO nanorods were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). And crystal structure was characterized by X-ray diffraction (XRD) spectroscopy. Inductively-coupled plasma atomic emission spectroscopy (ICP-AES) confirmed the Fe-doping of ZnO nanorod arrays with a concentration of 0.9 wt.%. In addition, Fe-doped ZnO nanorod showed the enhancement of photoluminescence (PL) intensity in green-yellow emission.     

A simple and rapid method to graft hydroxyapatite on carbon nanotubes

Herein a simple and effective approach is introduced to functionalize single walled carbon nanotubes (SWCNTs) by in-situ grafting of hydroxyapatite (HA). The pristine SWCNTs were chemically activated through introduction of carboxylic groups on their surfaces by refluxing in the mixture of H(2)SO(4) and HNO(3). The resulting carboxylated SWCNTs were further utilized for grafting of HA. The Fourier transform infrared and Raman spectroscopic studies demonstrated the formation of HA and its grafting over SWCNTs. The phase composition of HA and existence Ca(2+) and PO(4) (3-) ions were studied using X-ray diffraction and energy dispersive X-ray analyses, respectively. The surface morphology of functionalized SWCNTs was analyzed using scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis confirmed the existence of HA on SWCNTs by exhibiting different thermogram for pure HA and functionalized SWCNTs. Overall this method produced uniform grafting of low crystalline HA on carboxylated SWCNTs with strong interfacial bonding.     

Growth of silicon carbide nanorods from the hybrid of lignin and polysiloxane using sol-gel process and polymer blend technique

We report here the formation of silicon carbide (SiC) nanorods from organic-inorganic hybrid of the commercially available lignin and sol-gel derived nanosized silica. The SiC nanorods were identified by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface morphology shows the formation of continuous nanorods of diameter in the range of 50-200 nm. The X-ray diffraction (XRD) pattern show peaks at 2θ = 35.5° and 60.2° indicate the formation of β-SiC and a sharp peak at 2θ = 22.1° suggests the presence of unreacted crystalline silica (crystoballite). The characteristic vibration of SiC at 791 cm^− 1 in Fourier transform infrared spectroscopy (FTIR) was also observed.     

原位生成法制备单分散的纳米氧化锌分散液

用ZnCl2作原料,PVP作分散剂,在160℃下采用原位生成法制得单分散、具有良好晶体结构和规则外形的ZnO纳米单晶分散液,用透射电子显微镜、X射线衍射、紫外/可见分光光度计等测试手段对其进行了表征.讨论了工艺条件对纳米ZnO尺寸和形貌的影响,并对其生长机理做了初步探讨.     

Modulation of field emission properties of znO nanorods during arc discharge

Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.     

焙烧室温条件固相反应制备前驱物合成SnO2纳米棒的研究

室温条件下通过固相反应合成了SnO2纳米颗粒前驱物.在600～780℃对前驱物进行焙烧,在NaCl、KCl和KCl＋NaCl的熔盐介质中SnO2前驱物纳米颗粒自组装生长形成SnO2 纳米棒.利用TEM、XRD和XPS对SnO2纳米棒结构、形貌和成分进行了研究.结果表明SnO2纳米棒直径为20～80nm,长度从几百纳米到十几微米.分析了SnO2 纳米颗粒前驱体熔盐介质中的生长,利用固相转变生长可以解释SnO2纳米棒在熔盐介质中的生长机制.     

Solvothermal synthesis of α-MnSe uniform nanospheres and nanorods

α-MnSe uniform nanospheres and nanorods were prepared via a simple solvothermal reaction in ethanol amine at 180 °C for 12 h. X-ray powder diffraction (XRD), field-emission scanning electronic microscopy (FE-SEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to study the crystal structure and morphologies. The FE-SEM and TEM images showed that the α-MnSe nanospheres had a uniform diameter of about 200 nm and the size of the nanorods was about 50 nm in diameter. The optical properties of the products were also examined by means of UV–Vis absorption, excitation and photoluminescence spectroscopy.     

Template-free hydrothermal synthesis of PbS nanorod by the oriented attachment mechanism

In this work, PbS nanocubes and nanorods were fabricated via a facile hydrothermal method without using any template and surfactant. The structure and morphology of as-prepared PbS nanocrystals were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the anisotropic structure of PbS nanorods were composed of numerous assembled nanocubes, which had an uniform morphology with the mean diameters of about 100-200 nm and lengths of 0.5-7 μm. Furthermore, a possible growth mechanism was proposed to explain the formation of the nanorods on the basis of the time-dependent experimental results.     

Vapor growth and photoconductivity of single-crystal nickel-phthalocyanine nanorods

Nickel-phthalocyanines (NiPc) with planar aromatic structures are ideal building blocks for organic nanostructures. They can self-assemble into stacks through π-π interaction, exhibit high thermal and chemical stabilities, and possess outstanding electrical and optical properties. Herein, single-crystal NiPc nanorods were synthesized by a facile vapor transfer deposition method. Their nanostructures and compositions were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) in detail. The deposited NiPc nanorods were found to be the β-phase single crystals. Moreover, the NiPc nanorod-based devices were fabricated and exhibited high photocurrent upon white-light illumination. This indicates that the NiPc nanorods can be considered as a candidate material for fabricating photoelectric devices.     

A parametric study of single-wall carbon nanotube growth by laser ablation

Results of a parametric study of carbon nanotube production by the double-pulse laser oven process are presented. The effect of various operating parameters on the production of single-wall carbon nanotubes (SWCNTs) is estimated by characterizing the nanotube material using analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermo gravimetric analysis and Raman spectroscopy. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure, flow rate, inner tube diameter, as well as its material, and oven temperature. It was found that the material quality and quantity improve with deviation from normal operation parameters such as laser energy density higher than 1.5 J/cm2, pressure lower than 67 kPa, and flow rates higher than 100 sccm. Use of helium produced mainly small diameter tubes and a lower yield. The diameter of SWCNTs decreases with decreasing oven temperature and lower flow rates.     

Growth of aligned hexagonal ZnO nanorods on FTO substrate for dye-sensitized solar cells (DSSCs) application

This article reports a facile growth of well-crystalline aligned hexagonal ZnO nanorods on fluorine-doped tin-oxide (FTO) substrate via non-catalytic thermal evaporation process. The morphological investigations done by field-emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) reveal that the grown products are aligned hexagonal ZnO nanorods which are grown in a very high density over the whole substrate surface. The detailed structural properties observed by high-resolution TEM equipped with selected area electron diffraction (SAED) and X-ray diffraction (XRD) pattern confirmed that the synthesized nanorods are well-crystalline possessing wurtzite hexagonal phase and preferentially grown along the c-axis direction. A sharp and strong UV emission at 381 nm in room-temperature photoluminescence (PL) spectrum showed that the as-grown ZnO nanorods possess excellent optical properties. The as-grown nanorods were used as photo-anode for the fabrication of dye-sensitized solar cells (DSSCs) which exhibits an overall light-to-electricity conversion efficiency (ECE) of 0.7% with V(oc) of 0.571 V, J(sc) of 2.02 mA/cm2 and FF of 0.58.     

ZnO单晶堆垒纳米棒的制备与表征

在Au点阵模板上磁控溅射ZnO薄膜,然后在O2气氛下1000℃退火制备了ZnO单晶堆垒纳米棒。采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)和傅立叶变换红外(FTIR)光谱对样品进行分析。结果表明,ZnO纳米棒是由诸多单晶堆垒而成,每个单晶均为六方纤锌矿结构,纳米棒直径在100nm左右。初步探讨了ZnO单晶堆垒纳米棒可能的生长机理。     

Carbon Nanotubes Coated Acoustic and Optical VOCs Sensors: Towards the Tailoring of the Sensing Performances

This work is focused on the room temperature sensitivities and response times analysis against aromatic volatile organic compounds of both silica optical fiber and quartz crystal microbalance sensors, coated by single-walled carbon nanotubes (SWCNTs) Langmuir-Blodgett multilayers as highly sensitive nanomaterials. The fabricated samples have been characterized by means of X-ray diffraction, high-resolution transmission electron microscopy and scanning electron microscopy, silica optical fiber, and quartz crystal microbalance transducers have been simultaneously exposed at room temperature to toluene and xylene individual vapors in the ppm range. For each transducer type, a time division multiplexing approach has been exploited, enabling the simultaneous interrogation of up to 8 optical and 6 acoustic probes, respectively. The results obtained indicate that both optical and acoustic sensors provide very high reproducibility and sensitivity either towards toluene or xylene, with a resolution of few hundreds of ppb. Furthermore, sensitivities and response times turned out to be dependent on the particular analytes used for the vapors testing. Both transducer types demonstrate a similar response time, while with regard the recovery time, the optical detection seems to be significantly faster than the electrical counterpart. The effect of the SWCNTs monolayers number on sensors sensitivity and response time has also been investigated, demonstrating the possibility to enhance the performances of the proposed transducers by tailoring the geometric properties of the sensitive nanomaterial.     

Preparation and gas sensing properties of p-type La-Bi-Fe-O nanorods

La-Bi-Fe-O nanorods were prepared for the first time via a facile hydrothermal method without any surfactant. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the structure and morphology of the material. The semiconductive La-Bi-Fe-O nanorods are mainly composed of orthorhombic Bi₂Fe₄O₉ and a small amount of orthorhombic La_1.08Bi_0.92O_3.03. The gas sensing properties of the sensor based on La-Bi-Fe-O nanorods were studied and the nanorods exhibited a p-type behavior. Both the sensitivity and selectivity of the sensor towards formaldehyde were very high, and the sensor could be used to detect formaldehyde as low concentration as 5 ppm. More importantly, the operation temperature of the La-Bi-Fe-O sensor was low. This would be very significant in applications, such as detecting and preventing indoor formaldehyde pollution.     

Synthesis and characterizations of Pt nanorods on electrospun polyamide-6 nanofibers templates

We report on the synthesis of platinum (Pt) nanorods by using ultrafine polyamide-6 nanofibers templates produced via electrospinning technique. These ultrafine polyamide-6 nanofibers can be utilized as the templates for growing Pt nanorods after modifying them optimally by plasma passivations. The morphological, structural, optical and electrical properties of the template assisted Pt nanorods were studied by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), photoluminescence (PL) and current–voltage (I–V) characteristics. The ability to fabricate the ultrafine size controlled Pt nanorods on polyamide-6 templates with optimized growth parameters in real time can be utilized for the variety of technological applications. Therefore, it is possible to obtain high quality with size control Pt nanorods. Once obtaining the high quality metal nanorods on polymer templates, the same can be adapted for the electronic device fabrication.