ZnO纳米棒Al掺杂和A1,N共掺杂的制备技术与光致发光性能

采用水热法首先合成了Al掺杂ZnO(AZO)纳米棒,在此基础上通过550℃的氨气氛中退火制备了Al,N共掺杂ZnO(ANZ())纳米棒.运用X射线衍射(XRD),场发射扫描电镜(FESEM),透射电子显微镜(TEM),X射线能谱(EDS)和光致发光(PL)对样品进行了表征与分析.结果表明,制备的AZO和ANZ()纳米棒...     

A simple microwave-assisted decomposing route for synthesis of ZnO nanorods in the presence of PEG400

In the paper, a simple microwave-assisted decomposing reaction in the presence of PEG400 has been successfully developed to synthesize ZnO nanorods with 10-25 nm of diameter and 60-200 nm of length. The product was analyzed and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and HRTEM. Ultraviolet-visible (UV-vis) absorption peak of ZnO nanorods shows a distinct blue shift from that of the bulk and the Photoluminescence (PL) spectrum exhibits a strong near-band-edge emission at 385 nm. Further experiments have also been designed, and the results show that microwave radiation and surfactant PEG400 all played an important role on the formation of ZnO nanorods.     

Effect of ammonia water on the morphology of monoethanolamine-assisted sonochemicaly synthesized ZnO nanostructures

In the present work, ZnO nanostructures were synthesized by monoethanolamine (MEA)-assisted ultrasonic method at low temperature. Structural analysis was carried out by X-ray diffraction (XRD) confirmed the formation of hexagonal wurtzite structure of ZnO. The effect of ammonia water on the molecular structure of MEA, and its effect on the morphology of ZnO nanostructures were monitored by electron microscopy. Scanning electron microscopy (SEM) results suggest that ZnO nanoparticles with 100 nm in diameter were produced in case of MEA-assisted ultrasonic method. However, as ammonia water was added into the reaction system the morphology of ZnO nanoparticles changed into nanorods, flower-like nanostructures and finally microrods. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies showed that as prepared ZnO nanostructures were single crystalline in nature and grew in different directions resulted in the formation of various structures. The growth mechanism of as prepared ZnO nanostructures was discussed in detail. It was proposed that the addition of ammonia water into the reaction system resulted into the formation of ethylene diamine (EDA) which directed the growth of ZnO. The optical property was studied by photoluminescence (PL) spectroscopy showed only UV emission and no defects mediated visible emission.     

Structural,photoluminescence and picosecond nonlinear optical effect of In-doped ZnO nanowires

In-doped ZnO (IZO) nanowires were grown using the chemical vapour deposition method. The IZO nanowires have been characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and UV–Visible spectroscopy. The PL results demonstrated a larger band-gap for the IZO nanowires in comparison to the undoped ZnO. Two major emission peaks were observed for the IZO nanowires, one originated from the free exciton recombination (ultraviolet emission) and another possibly related to the deep-level emission (visible emission). Furthermore, the nonlinear optical characteristic of the nanowires was studied using picosecond Z-scan technique. The experimental results show that the two and three-photon absorption coefficient of samples were able to be observed. These studies make the promising potential applications of the samples in the development of multifunctional all-optical devices.     

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.     

Preparation and characterization of ZnO/ZnS core/shell nanocomposites through a simple chemical method

In this paper, we reported the preparation of ZnO/ZnS core/shell nanocomposites by sulfidation of ZnO nanostructures via a simple hydrothermal method. The precursors of bare ZnO nanoparticles and ZnO nanorods were synthesized by a surfactant-assisted hydrothermal growth. The structural, morphological, and element compositional analysis of bare ZnO nanostructures and ZnO/ZnS core/shell nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy techniques. The XRD results indicated that the phase of bare ZnO nanoparticles and ZnO nanorods was wurtzite structure, and the phase of coated ZnS nanoparticles on the surface of bare ZnO nanostructures was sphalerite structure with the size of about 8 nm. Photoluminescence measurement was carried out, and the PL spectra of ZnO/ZnS core/shell nanocomposites revealed an enhanced UV emission and a passivated orange emission compared to that of bare ZnO nanostructures. In addition, the growth mechanism of ZnO/ZnS core/shell nanostructures through hydrothermal method was preliminarily discussed.     

Sonochemical method for the preparation of ZnO nanorods and trigonal-shaped ultrafine particles

ZnO nanorods and trigonal-shaped ZnO ultrafine particles were synthesized by sonochemical method through the decomposition of zinc acetate dihydrate in paraffin oil. ZnO nanorods and trigonal-shaped ZnO ultrafine particles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and UV–visible spectrophotometer. One strong UV emission peak at 390 nm was observed.     

Effects of Mg-contents and substrate parameters on structure and optical properties of Mg-doped ZnO nanorods fabricated by hydrothermal method

Mg-doped ZnO nanorods with different contents have been fabricated on various substrates by hydrothermal method. The effects of Mg-contents and different substrates on structural and optical properties are analyzed by scanning electron microscopy, X-ray diffraction, photoluminescence (PL) spectra, energy dispersive X-ray spectroscopy and Raman spectroscopy. The results reveal that the Mg-doped ZnO nanorods possess good crystalline quality and morphology when the molar ratio of Mg/Zn is 1. The PL spectra show that the UV emissions have an obvious blue shift with the increase of Mg-content. The results of investigation for the samples grown on different substrates show that the crystal quality and morphology of the samples grown on ZnO layer are perfect, and the UV emission also occurs blue shift owing to the effects of different substrates.     

室温固相法合成ZnO纳米棒及其光学特性

在氯化钠存在下,以硫酸锌和氢氧化钠为原料,采用一步室温固相法制备了纳米氧化锌.XRD、TEM分析结果表明:所得纳米氧化锌为棒状,直径约10nm左右,长度约100～160nm.利用紫外-可见分光光度计测试了光吸收性能,发现ZnO纳米棒对200～380nm波长范围的光有很强吸收性,在可见光范围内,也有较强的吸收.ZnO纳米棒在550nm左右具有较弱的荧光发光峰且ZnO纳米棒较普通氧化锌发光峰波长发生了明显的红移.     

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.     

Preparation and characterization of MgO nanorods coated with SnO2

MgO nanorods have been grown by thermal evaporation of Mg3N2 powders on Si (100) substrates coated with gold (Au) thin films. The MgO nanorods grown on Al2O3 (0001) were 0.1-0.2 microm in diameter and up to a few tens of micrometers in length. MgO/SnO2 coaxial nanorods have also been prepared by atomic layer deposition (ALD) of SnO2 onto the nanorods. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the MgO-cores and the SnO2 shells of the annealed coaxial nanorods are of a single crystalline nature with cubic and orthorhombic structures, respectively. The photoluminescence (PL) spectroscopy analysis results show that SnO2 coating slightly increases the PL emission intensity of MgO nanorods. The PL emission of the SnO2-coated MgO nanorods is found to be considerably enhanced by thermal annealing and to strongly depend on the annealing atmosphere. The PL emission intensity of the MgO/SnO2 coaxial nanorods has been significantly increased by annealing in a reducing atmosphere. The origin of the PL enhancement by annealing in a reducing atmosphere is discussed on the basis of energy-dispersive X-ray spectroscopy analyses.     

Synthesis of wurtzite ZnS nanorods by microwave assisted chemical route

ZnS nanorods were synthesized by microwave assisted chemical method. Polyvinylpyrrolidone (PVP) was used as a capping agent to stabilize the nanostructure. Synthesized ZnS nanorods were characterized by X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), UV-visible spectrophotometry (UV), photoluminescence spectroscopy (PL) and Fourier transform Infra-red spectroscopy (FTIR). The results showed that the nanorods have wurtzite phase crystal structure and exhibits near band edge luminescence in the ultra violet region. The diameter of the synthesized PVP capped ZnS nanorods is about 600 nm. The possible growth mechanism of the ZnS nanorods could be attributed to the oriented attachment effect.     

Solvothermal synthesis of hexagonal ZnO nanorods and their photoluminescence properties

Pure hexagonal ZnO nanorods were synthesized by low-temperature (90 °C) solvothermal treatment of zinc acetate in 40-80 wt.% hydrazine hydrate aqueous solutions. The products were characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), selected area electron diffraction (SAED), and room temperature photoluminescence (RTPL) spectra. They show a strong UV emission at around 380 nm upon excitation at 360 nm using a Xe lamp at room temperature. The influence on the quality of the nanorods was investigated while the content of the solvent changed. The as-synthesized ZnO nanorods are promising materials for nanoscale optoelectronic devices due to their excellent UV emission properties.     

Preparation of ZnO nanorods through wet chemical method

The different morphologies of nanorods have been obtained via a simple wet chemical method in the present of polyethylene glycol (PEG, M_w = 4000) by using zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and ammonium hydroxide (NH₃·H₂O) as the starting materials. Samples were characterized by XRD, EDS, TEM, SEM, ED and PL. XRD results prove the formation of ZnO with wurtzite structure. The ED and HRTEM reveal that single ZnO nanorod is single crystal and preferentially grows up along the [001] direction. The PL spectra showed that the ZnO nanorods have blue emission at 466 nm and green-yellow emission at 542 nm. The influence of reaction temperature, pH in system and evaporation of ammonia on the morphology has been investigated. A possible growth mechanism of ZnO with various morphologies is discussed.     

Quantum confinement effect of CdS nanoparticles dispersed within PVP/PVA nanocomposites

Nanocomposite films of CdS nanoparticles within PVP/PVA blend were prepared. The prepared films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Ultraviolet–visible spectroscopy (UV–vis), transmission electron microscopy (TEM) and photoluminescence (PL) spectra. The amount of Cd⁺ used strongly influenced the size of the CdS nanoparticles, which was confirmed by XRD, UV–vis absorption spectra, PL emission spectra and TEM images. Smaller sized CdS nanoparticles were formed in higher content of cadmium. The results of XRD indicate that CdS nanoparticles were formed with hexagonal phase in the polymeric matrix. PL and UV–vis spectra reveal that nanocomposite films shows quantum confinement effect. Optical band gap and particle size were calculated and is in agreement with the results obtained from TEM data. The direct energy band gap was increased up to 2.86 eV.     

RGO/ZnO纳米棒复合材料的合成及光催化性能

采用水热合成法制备ZnO纳米棒及RGO/ZnO纳米棒复合材料。研究不同含量的RGO对RGO/ZnO纳米棒复合材料光催化活性的影响。采用X射线衍射仪(XRD)、场发射电子显微镜(FESEM)、光电子能谱仪(XPS)及漫反射紫外-可见吸收光谱(UV-Vis)检测手段对RGO/ZnO进行表征。结果显示:RGO与ZnO纳米棒成功复合。加入GO的含量不同,获得的RGO/ZnO样品在可见光区域的吸光度值不同。以甲基橙作为模拟污染物的光催化结果表明,RGO/ZnO复合材料具有高的紫外-可见光光降解效率,加入GO与ZnO的质量比为3%时,样品紫外-可见光光催化性能最佳,120min内甲基橙基本可以完全降解;且在波长大于400nm可见光照射下,RGO/ZnO具有一定的可见光活性,180min内其降解甲基橙效率最大可达26.2%。同时,RGO/ZnO具有较好的光稳定性。     

Synthesis,characterization and growth mechanism of ZnO nanowires on NiCl<Subscript>2</Subscript>-coated Si substrates

Well-crystallized ZnO nanowires have been successfully synthesized on NiCl₂-coated Si substrates via a carbon thermal reduction deposition process. The pre-deposited Ni nanoparticles by dipping the substrates into NiCl₂ solution can promote the formation of ZnO nuclei. The as-synthesized nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectrum. The results demonstrate that the as-fabricated nanowires with about 60 nm in diameter and several tens of micrometers in length are preferentially arranged along [0001] direction with (0002) as the dominate surface. Room temperature PL spectrum illustrates that the ZnO nanowires exist a UV emission peak and a green emission peak, and the peak centers locate at 387 and 510 nm. Finally, the growth mechanism of the nanowires is briefly discussed.     

Synthesis of brush-like CdS nanorod arrays through a novel hydrothermal reaction of simultaneous solvent-oxidation-hydrolysis

Brush-like CdS arrays composed of well-arranged nanorods have been successfully synthesized for the first time through a novel chemical reaction under the low-temperature hydrothermal condition. The reaction can be described as the solvent-oxidation-hydrolysis reaction among Cd, H₂O and thiourea. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL). TEM results showed that these nanorods were about 20?nm wide with lengths varying from 1.25?µm to 3.5?µm. XRD pattern indicated that as-obtained CdS was hexagonal phase with good crystallinity. PL spectrum showed the products had novel optical property from the bulk counterpart. The formation mechanism was also explored.     

Defect induced room temperature ferromagnetism in well-aligned ZnO nanorods grown on Si (100) substrate

In this work, we report the fabrication of high quality single-crystalline ZnO nanorod arrays which were grown on the silicon (Si) substrate using a microwave assisted solution method. The as grown nanorods were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photo-luminescence (PL) and magnetization measurements. The XRD results indicated that the ZnO nanorods are well oriented with the c-axis perpendicular to the substrate and have single phase nature with the wurtzite structure. FE-SEM results showed that the length and diameter of the well aligned rods is about ~ 1 μm and ~ 100 nm respectively, having aspect ratio of 20-30. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at ~ 583 nm might be attributed to surface oxygen vacancies or defects. Magnetization measurements show that the ZnO nanorods exhibit room temperature ferromagnetism which may result due to the presence of defects in the ZnO nanorods.     

Synthesis of 1-D ZnO nanorods and polypyrrole/1-D ZnO nanocomposites for photocatalysis and gas sensor applications

1-D ZnO nanorods and PPy/1-D ZnO nanocomposites were prepared by the surfactant-assisted precipitation and in situ polymerization method, respectively. The synthesized nanorods and nanocomposites were characterized by UV–Vis spectrophotometer, Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM), which gave the evidence of 1-D ZnO nanorods, polymerization of pyrrole monomer and strong interaction between PPy and 1-D ZnO nanorods, respectively. Photocatalytic activity of 1-D ZnO nanorods was conducted by 3³ level full-factorial design to evaluate the effect of three independent process variables viz., dye concentration (crystal violet), catalyst concentration (1-D ZnO nanorods) and the reaction time on the preferred response: photodegradation efficiency (%). The PPy/1-D ZnO nanocomposites were used for the sensing of NH₃, LPG, CO₂ and H₂S gases, respectively, at room temperature. It was observed that PPy/1-D ZnO nanocomposites with different 1-D ZnO nanorod weight ratios (15 and 25%) had better selectivity and sensitivity towards NH₃ at room temperature.