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1.
CdSe nanostructures with urchin-like shape were successfully synthesized in water-in-oil (W/O) microemulsion. The phase structure, morphology, optical property, and specific surface area of the CdSe products were characterized. The X-ray powder diffraction pattern of the product showed that it is pure CdSe in zinc blende structure rather than thermodynamically favored wurtzite structure. It is found that numerous one-dimensional CdSe nanorods radiate from the center of the agglomerate to form urchin-like nanostructures and grow along the (111) crystal planes. The photoluminescence spectrum of the urchin-like nanostructures indicated that there is a blue-shift as compared with that of the bulk CdSe. Additionally, these interesting urchin-like nanostructures showed an increased specific surface area. 相似文献
2.
Without the assistance of any surfactant and template, urchin-like In 2S 3 microspheres constructed with nanoflakes of about 15–30 nm thickness were synthesized via the hydrothermal reaction of indium trichloride and thioacetamide in 6.25 vol.% acetic acid aqueous solution at 80 °C for 6–24 h. The as-synthesized nanostructured In 2S 3 could be completely transformed into In 2O 3 when subjected to heating in air at 600 °C for 5 h. The resultant In 2O 3 consisted of urchin-like microsphere built up by 20–30 nm thickness nanoflakes and 20–40 nm nanoparticles. X-ray diffraction, field emission scanning electronic microscope and energy dispersive X-ray spectroscopy have been used to characterize the In 2S 3 and In 2O 3 nanostructures obtained. 相似文献
3.
Novel hierarchical urchin-like hollow SnO2 nanostructures have been synthesized via a facile one-pot template-free hydrothermal approach. The size and density of the SnO2 prickles as well as the morphology of the SnO2 spheres can be modified by tuning the synthetic parameters such as temperature, time, concentration, as well as pH value. The novel hierarchical nano-sized SnO2 hollow urchins possess enriched prickles with diameters of 5-20 nm and lengths of < 70 nm and high surface area up to 116 m2 g(-1), exhibiting advanced sensing performance to the ethanol vapor due to the special hierarchical nanostructures and being promising for the potential gas sensor material. 相似文献
4.
Highly regular urchin-like NiS architectures were synthesized on a large scale by solvothermal treatment of a single-source molecular precursor of nickel diethyldithiocarbamate [Ni(DDTC) 2] at 180 °C. The urchin-like architectures, with an average diameter of ∼16 μm, were composed of single-crystalline NiS nanoneedles with a diameter of ∼100 nm and a length of up to 8 μm. It was revealed that the solvent medium can strongly affect the composition and crystal phases of the products, and a surfactant is crucial to form urchin-like patterns. Based on the experimental observations, a probable three-step growth mechanism is proposed to explain the formation of the urchin-like nanostructures. The optical properties were investigated by ultraviolet-visible (UV-vis) absorption spectroscopy. This simple and mild single-source solvothermal route may be expected to extend to fabricating other inorganic nano-/micro-superstructures with novel morphologies and complex architectures. 相似文献
5.
Different morphologies of 3D SnO 2 nanostructures, including sphere-like, net-like, and flower-like, have been successfully synthesised via a facile hydrothermal method. The products were characterized by X-ray diffraction and scanning electron microscopy. The possible growth mechanism of different SnO 2 nanostructures was discussed in detail. We found that the citric acid and PEG play significant roles in synthesizing the flower-like and net-like nanostructures. Furthermore, the gas-sensing properties of the samples were investigated towards the reducing ethanol gas. The results indicate that the flower-like and net-like SnO 2 show larger gas sensing properties than sphere-like SnO 2. 相似文献
6.
In the present work, pure ZrO2@SnO2 and Samarium (Smx) (x?=?1%, 8% and 12%)-doped ZrO2@SnO2 nanoparticles (NPs) successfully synthesized by facile low-cost co-precipitation technique. As-synthesized nanostructures (NS) were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV–visible, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) spectroscopic investigation. The tetragonal crystal phase of the as-synthesized Smx:ZrO2@SnO2 NS confirmed by XRD analysis. The observed peak shift in the XRD patterns confirmed incorporation of dopant into host lattice. The Smx:ZrO2@SnO2 NS present irregular spherical morphology and high agglomeration confirmed by FESEM microscope analysis. The presence of functional groups, chemical bonding, chemical constituents and valence state of the NS confirmed by FT-IR and XPS analysis. The Smx:ZrO2@SnO2 NS showed higher surface area and smaller optical band gap (454 cm2/g and 2.12 eV) than the pure ZrO2@SnO2 NS (189–196 cm2/g and 2.84 eV). Photoluminescence (PL) spectra of undoped ZrO2@SnO2 and Smx:ZrO2@SnO2 NS exhibited oxygen vacancies. Undoped ZrO2@SnO2 NS exhibited emission intensity at 370.6 nm (λexcitation?=?300 nm) whereas, Smx:ZrO2@SnO2 NS showed emission intensities at 453.4 nm, 476.3 nm, 601.3 nm (λexcitation?=?300 nm). Electrical property studies of Smx:ZrO2:SnO2 (1%, 8% and 12%) NS showed large variation in Hall constant (0.125?×?106 cm2/coulomb to 0.647?×?106 cm2/coulomb) with proportionately large variation in the resistivity (147.8 Ω-cm to 456.8 Ω-cm) for all the doped samples as compared with pure ZrO2@SnO2 NS. The Sm3+-doped ZrO2@SnO2 NS showed higher stability, intense PL emission and enhanced electrical properties. 相似文献
8.
High purity and yield of ZnO nanobelts, nanocombs and nanowires have been synthesized using a simple catalyst-free vapor transport process and their growth mechanism and photoluminescence properties have been investigated. Transmission electron microscopy and selected-area electron diffraction analyses reveal that the intrinsic growth behaviors of ZnO vary with the growth temperature, leading to the formation of nanostructures with different morphologies. These ZnO nanostructures show a UV emission at about 385 nm and a broad green emission around 500 nm in their photoluminescence spectra, and the green to UV emission intensity ratio is determined by their microstructures. 相似文献
9.
TiO 2 particles, rods, flowers and sheets were prepared by hydrothermal method via adjusting the temperature, the pressure and the concentration of TiCl 4. The as-prepared TiO 2 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra and N 2 adsorption–desorption measurements. It was found that pressure is the most important factor influencing the morphology of TiO 2. The photocatalytic activity of the products was evaluated by the photodegradation of aqueous brilliant red X-3B solution under UV light. Among the as-prepared nanostructures, the flower-like TiO 2 exhibited the highest photocatalytic activity. 相似文献
10.
采用离子液体法,以离子液体(DESs)为溶剂,柠檬酸三钠为还原剂,氯金酸为晶种,硝酸银为银源,制备了Ag/AgCl纳米枝状结构。利用SEM、XRD、EDS对样品的形貌、成分、结构进行了表征分析,并测试了样品的光催化性能。结果表明,当反应温度为160℃,反应时间为24h时,可获得完整的Ag/AgCl纳米枝状结构;枝状结构的形成是基于AgCl在还原剂作用下不断向Ag转换过程的结果;产物具有较好的光催化效果,并且随着反应时间的延长,产物的光催化性能减弱。 相似文献
11.
In the present work, we report the solvothermal synthesis of transition metal-doped tungsten oxide nanostructures and their optical properties. Uniform, well-defined Co-doped tungsten oxide nanoblocks consisting of ultrathin nanowires, lenticular bundled Zn-doped tungsten oxide nanorods, and plate-shaped or flower-like Fe-doped tungsten oxide particles have been successfully prepared with the addition of different dopants. The doping of Co and Zn ions may prohibit the oriented growth of the tungsten oxide nanowires and favor their self-assembly, leading to the formation of bundled nanoblocks and nanorods. The Fe-doped tungsten oxide flowers may result from the ordered arrangement of single nanoplates. The band gaps of undoped, Fe-, Zn-, and Co-doped tungsten oxides are found to be 2.92, 2.78, 2.62, and 2.52 eV, respectively. 相似文献
12.
This paper describes a thermal evaporation method that generated large-scale novel doorframe-like ITO nanostructures by regularly switching flow rate of the carried gas. Their morphology and microstructures were determined by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy. The as-synthesized doorframe-like nanostructures are single crystal with diameters ranging from hundreds of nm to about 1 μm. The growth direction of the doorframe-like nanostructures are < 100> and < 011> and the growth process follows a self-catalytic vapor-liquid-solid mechanism. The PL spectrum of the doorframe-like nanostructures shows two emission bands around 418 and 505 nm, which is probably resulted from oxygen vacancies, oxygen-indium vacancy pairs and impurity level, respectively. 相似文献
13.
CuO nano-particles, nano-rods, nano-sheets and nano-flowers were synthesized by the hydrothermal routes with copper salts under different additions. The obtained samples were characterized by X-ray diffraction and scanning electron microscopy. We investigated the effects of precursors on the formation of CuO with different morphologies and proposed their possible formation mechanisms. In addition, the obtained CuO nano-flowers are found to show better sensing performances than the other three low-dimensional CuO nanostructures. Our results also demonstrate that gas sensing properties of nanocrystals can be significantly improved by tailoring shape and morphology of the nanocrystals. The CuO nano-flowers may hold substantial promise in low-dimensional gas-sensing applications. 相似文献
14.
We demonstrate an aqueous solution method for the synthesis of a Ag-TiO 2-reduced graphene oxide (rGO) hybrid nanostructure (NS) in which the Ag and TiO 2 particles are well dispersed on the rGO sheet. The Ag-TiO 2-rGO NS was then used as a template to synthesize Pt-TiO 2-rGO NS. The resulting hybrid NSs were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM),
energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform
infrared (FTIR) spectroscopy, UV-vis spectroscopy, Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS),
and catalytic studies. It was found that TiO 2-rGO, Ag-TiO 2-rGO and Pt-TiO 2-rGO NSs all show catalytic activity for the reduction of p-nitrophenol to p-aminophenol by NaBH 4, and that Pt-TiO 2-rGO NS exhibits the highest catalytic activity as well as excellent stability and easy recyclability.
相似文献
15.
PbCrO4 with different morphologies have been synthesized via a facile sonochemical route from an aqueous solution of lead acetate and potassium dichromate in the presence of nitrilotriacetate acid (H3NTA). The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The pH and the concentration of complexing reagent were found to have close relation with morphology of the final product. The possible growth mechanism of PbCrO4 microcube has been proposed. UV-Vis spectra and room-temperature photoluminescence of the PbCrO4 micro/nanostructures have also been investigated. Results showed that all the samples possessed strong photoluminescence (PL) properties, suggesting that the micro/nanostructures could be used in novel optoelectronic devices. 相似文献
16.
Uniform clusters of Pt have been deposited on the surface of capping-agent-free CeO 2 nanooctahedra and nanorods using electron beam (e-beam) evaporation. The coverage of the Pt nanocluster layer can be controlled
by adjusting the e-beam evaporation time. The resulting e-beam evaporated Pt nanocluster layers on the CeO 2 surfaces have a clean surface and clean interface between Pt and CeO 2. Different growth behaviors of Pt on the two types of CeO 2 nanocrystals were observed, with epitaxial growth of Pt on CeO 2 nanooctahedra and random growth of Pt on CeO 2 nanorods. The structures of the Pt clusters on the two different types of CeO 2 nanocrystals have been studied and compared by using them as catalysts for model reactions. The results of hydrogenation
reactions clearly showed the clean and similar chemical surface of the Pt clusters in both catalysts. The support-dependent
activity of these catalysts was demonstrated by CO oxidation. The Pt/CeO 2 nanorods showed much higher activity compared with Pt/CeO 2 nanooctahedra because of the higher concentration of oxygen vacancies in the CeO 2 nanorods. The structure-dependent selectivity of dehydrogenation reactions indicates that the structures of the Pt on CeO 2 nanorods and nanooctahedra are different. Thes differences arise because the metal deposition behaviors are modulated by
the strong metal-metal oxide interactions. 相似文献
17.
Four different mediums have been developed for the synthesis of PbSe nanostructures, with different size and morphology. The particles were obtained in solid state medium with size of only 60 nm on average which are much smaller than those gained in liquid and molten state mediums. The growth mechanisms of these PbSe nanostructures were discussed. Results show that the state of medium have a direct impact on the size of PbSe nanostructures and the alkalinity of environment plays a key part in the formation of PbSe nanocubes. On the other hand, the electrochemical property of two typical nanostructures was studied. In the CV curves, there are four reaction peaks corresponding to oxidation of the PbSe and Pb(OH) 2, and the reduction of PbO 2 and Pb(OH) 2. Otherwise, nanorods with size of only 60 nm have greater structural stability than nanocubes. 相似文献
19.
Novel self-organized hierarchical SnO2 nanostructures have been successfully prepared by vapor phase transport with the assistance of a stainless-steel grid at 950 degrees C. Scanning electron microscopy shows that the synthesized product displays interesting sallow-like morphology, in which numerous secondary branches (beak-like nanowires) are grown randomly around the main stems (microwires). Transmission electron microscopy analysis indicates that the branches grow along a direction of [100] and the beak is formed with the growth direction switching to [110]. A room temperature photoluminescence spectrum of the present SnO2 nanostructures shows a strong emission at 572 and 604 nm(-1). 相似文献
20.
Bundlelike VO(2)(B) nanostructures were synthesized via a hydrothermal method, and VO(2)(M(1)/R) nanobundles were obtained after a heat-treatment process. Structural characterization shows that these nanobundles are self-assembled by VO(2) nanowires, and VO(2)(M(1)/R) nanobundles have better crystallinity. Temperature-dependent field-emission (FE) measurement indicates that FE properties of these two phases of nanobundles can both be improved by increasing the ambient temperature. Moreover, for the VO(2)(M(1)/R) nanobundles, their FE properties are also strongly dependent on the temperature-induced metal-insulator transitions process. Compared with poor FE properties found in the insulating phase, FE properties were significantly improved by increasing the temperature, and about a three-orders-of-magnitude increasing of the emission current density has been observed at a fixed field of 6 V/μm. Work function measurement and density-functional theory calculations indicated that the decrease of work function with temperature is the main reason that caused the improvement of FE properties. These characteristics make VO(2)(M(1)/R) a candidate material for application of new type of temperature-controlled field emitters, whose emission density can be adjusted by ambient temperature. 相似文献
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