Low temperature aqueous chemical synthesis of CdS sensitized ZnO nanorods

Cadmium sulfide nanoparticles (CNPs) sensitized zinc oxide nanorod arrays (ZNRs) were synthesized in the two step deposition process at relatively low temperature. The vertically aligned ZNRs were grown on the conducting glass substrates (FTO) using aqueous chemical method, followed by the deposition of CNPs at 70 °C using chemical bath deposition (CBD) technique. The samples were characterized by optical absorption, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). Further, the photoelectrochemical (PEC) performance of ZNRs with and without CNPs sensitization was tested in Na₂S-NaOH-S and Na₂SO₄ electrolyte, respectively. When the CNPs are coated on the ZNRs, the optical absorption is enhanced and band edge is shifted towards visible region (525 nm) as compared with ZNRs (375 nm). The sample sensitized with CNPs shows higher photoelectrochemical (PEC) performance with maximum short circuit current of (I_sc) 2.60 mA/cm².     

One-step solution synthesis of monodispersed ZnO nanowhiskers at low-temperature

In this paper, a one-step wet-chemical approach to synthesize monodispersed ZnO nanowhiskers is reported. Depending on the synthetic conditions used, the nanosized ZnO can be formed directly in aqueous solution at low-temperature. From the investigation of differential scanning calorimetry (DSC), thermogravimetry (TG) and X-ray diffraction (XRD), the resultant powders without high-temperature calcining were confirmed to be ZnO, and its crystal phase was hexagonal wurtzite structure, transmission electron microscope (TEM) observation revealed that ZnO nanowhiskers have diameters ranging from 30 to 50 nm and lengths up to 500 nm.     

A study of ZnO nanoparticles and ZnO-EG nanofluid

This study deals with the synthesis and characterisation of ZnO nanoparticles and suspension of ZnO-ethylene glycol (EG) nanofluid. Crystalline ZnO nanoparticles are synthesised using the chemical method. The nanofluids were synthesised by the dispersion of ZnO nanoparticles in EG solution using an ultrasonicator. The prepared ZnO nanoparticles are characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-Vis absorption spectrum. The particle size distribution and ultrasonic parameters of the synthesised nanofluid are measured with the help of acoustic particle sizer (APS-100) and ultrasonic interferometer. The observed features of ZnO nanoparticles and ZnO-EG nanofluids are discussed in correlation with known properties of other nanofluids.     

Simple method for preparation of cubic Ag nanoparticles and their self-assembled films

Thiol-derivatised cubic Ag nanoparticles were prepared by adding an AgNO₃ solution containing a trace amount of alkanethiol into a solution of NaBH₄ and sodium oleate. Their preparation and character were compared with randomly shaped Ag nanoparticles. The thiol was used purposely as orientation agent instead of protective agent. Transfer of cubic Ag nanoparticles from aqueous phase into organic phase or to the interface of aqueous/organic phase has resulted in self-assembled films on the surface of microscope slides and of many other substrates. Transmission electron microscope and UV–vis spectra were used to characterize the cubic Ag nanoparticles. The nanoparticle films were also observed using conventional optical and scanning electron microscope. The mechanisms of the nanoparticles phase-transfer and the formation of the self-assembled nanoparticle films are discussed.     

纳米ZnO晶体的制备及其荧光性能研究

采用直接沉淀法，通过改变沉淀剂（氨水、NaOH）及反应时间制备纳米ZnO粒子，并通过扫描电子显微镜、荧光显微镜对所得产物的形貌及其荧光性能进行分析表征。结果显示：不同沉淀剂制备的ZnO纳米粒子的形貌和尺寸均不相同，用Zn（NO3）2和NH3．H2O反应可制得花状的纳米粒子，而用Zn（NO3）2和NaOH反应则会生成球状的纳米粒子，其尺寸分别为500和200nm左右；反应前期，反应时间主要影响粒子的尺寸，随反应时间的增加粒子的形貌也发生变化；与以NaOH为沉淀剂制备的纳米ZnO粒子相比，以氨水为沉淀剂制备的纳米ZnO粒子具有好的荧光性能。     

导电纳米氧化锌颗粒的制备与表征

氧化锌由于氧空位等本征缺陷的存在表现出n型半导体的性质，该性质使得氧化锌纳米颗粒可以用作导电材料。为了提高纳米氧化锌颗粒的电导率，通过简单、经济、新颖的液相反应法和喷雾热解技术对纳米氧化锌进行Al掺杂，并分析了掺杂工艺、电导测试方法对纳米氧化锌导电颗粒电阻率的影响。     

Sol-gel synthesis,structural and enhanced photocatalytic performance of Al doped ZnO nanoparticles

In this research ZnO and Zn_1?x Al_xO (x = 1, 3, 5, 7% mol) nanoparticles were synthesized by sol-gel method. The effect of Al concentration on the structure, morphology, absorption spectra and photocatalytic properties investigated by using X-ray, TEM, EDS and UV–Vis spectrophotometer approaches. Hexagonal, spherical and rod-like structure was achieved as the dominant structure for undoped nanoparticles, low and high concentrations of doped Al, respectively. Photocatalytic activity of nanoparticles was measured by degradation of methyl orange as a pollutant under radiation of ultraviolet (UV). The experimental test results indicate that the best photocatalytic performance is at of 5% of Al. Furthermore, the doped ZnO nanoparticles have more activity in visible area compared with undoped nanoparticles. The absorption amount in this area increases by raising the Al concentrations. Furthermore, the band gap of the particles decreases from 3.22 eV to 2.93 eV by increasing Al percentage.     

单分散纳米TiO2的合成及表征

以钛酸四丁酯为原料和三乙醇胺为形态控制剂,采用溶胶-凝胶-水热法可以简单快速地合成单分散的TiO2纳米粒子.研究了反应物料配比、凝胶形成温度、水热处理温度等反应条件对粒子粒径及分散性的影响.采用XRD和TEM等手段对粒子的结构与形貌进行了表征.结果表明,三乙醇胺与钛酸四丁酯物质的量配比为2:1,凝胶形成温度为100℃,水热处理温度为140℃时,所合成的TiO2粒子分散性最好.     

One-step high-yield aqueous synthesis of size-tunable multispiked gold nanoparticles

Multispiked gold nanoparticles are required in large quantities for many fundamental studies and applications like (bio)sensing, but their preparation in high yield by the bottom-up chemical synthetic method is challenging. A water-based, non-'seed-mediated', straightforward method for the synthesis of gold nanoparticles with well-developed surface spikes is reported here. The yield of multispiked gold particles is very high (>90%). The method allows the tuning of the number and size of the spikes and the overall size of the particles, and hence the localized surface plasmon resonances of the particles over the broad spectral range in the visible and near-infrared. A mechanism for the evolution of twinned, sharp-tipped surface protrusions has been proposed based on systematic spectrophotometric and transmission electron microscopic studies, which were employed to elucidate the morphological features, structure, chemical composition, and optical properties of the multispiked gold nanoparticles.     

Fabrication of ZnO nanorods using metal nanoparticles as growth nuclei

ZnO nanorods were produced by pulsed laser deposition (PLD). Drops of nanoparticle colloid (gold or silver) were placed on silica substrates to form growth nuclei. All nanoparticles were monocrystalline, with well-defined crystal surfaces and a negative electrical charge. The ZnO nanorods were produced in an off-axis PLD configuration at oxygen pressure of 5 Pa. The growth of the nanorods started from the nanoparticles in different directions, as one nanoparticle could become a nucleus for more than one nanorod. The low substrate temperature used indicates the absence of a catalyst during the growth of the nanorods. The diameters of the fabricated 1-D ZnO nanostructures were in the range of 50-120 nm and their length was determined by the deposition time.     

Potato extract as reducing agent and stabiliser in a facile green one-step synthesis of ZnO nanoparticles

A facile green recipe was developed to synthesise highly pure, safe and durable zinc oxide nanoparticles (ZnO Nps) using homemade starch-rich potato extract. The ZnO Nps were synthesised using zinc nitrate and potato extract, and the whole reaction is carried out for 30 min at 80 °C. In the synthesis, starch-rich potato extract acted as the reducing agent and as a stabilising layer on freshly formed ZnO Nps. Hexagonal (wurtzite) shaped ZnO Nps with size about 20 ± 1.2 nm were synthesised and characterised using X-ray diffraction, transition electron microscope and scanning microscopy analyses. Fourier transform infrared spectral analysis indicated that highly pure ZnO nanopowders were obtained at higher temperatures. The use of environmentally benign and renewable material as the respective reducing and protecting agents, starch-rich potato extract, as well as a gentle solvent medium (H₂O), offered a simple and quite efficient procedure for the synthesis of ZnO Nps in neutral medium with promising potential for biological and biomedical applications.     

Synthesis of ZnO nanoparticles and study of their antibacterial and antifungal properties

In this paper, ZnO nanoparticles have been synthesized with and without the use of surfactants under different reaction conditions. The size of the ZnO nanoparticles varied in diameter (2 nm-28 nm) according to the reaction conditions employed. Promising particle size dependent antibacterial and antifungal activities of the ZnO nanoparticles have been observed. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (FTIR) techniques were used to characterize the particle size and morphology.     

溶液生长ZnO一维纳米阵列及其复合纳米结构的研究进展

对溶液生长ZnO一维纳米阵列的研究进展进行了评述,分析了晶种制备和溶液生长过程中各工艺因素对阵列微观形貌的影响,并介绍了在溶液中通过控制定点成核并利用有机基团调控ZnO晶体生长习性的合成路线用于构筑ZnO复合纳米结构的最新研究,指出了溶液生长ZnO一维纳米阵列和构筑复合结构中存在的问题及今后的研究方向.     

离子液体中微波辅助制备ZnO纳米棒及光学性能研究

在离子液体1-丁基-3甲基咪唑六氟磷酸盐[BMIM][PF6]水溶液中通过微波加热10min制备出ZnO纳米棒。用X射线衍射仪、场发射扫描电镜、紫外分光光度计和荧光分光光度计对其形貌、结构和性能进行了表征。研究表明,产物结晶性良好,产率高,大小均匀,平均直径为20nm,长度为400～500nm。通过对ZnO纳米棒形成机理和实验条件进行系统探讨,提出了三步反应机理,同时发现离子液体对产物的形貌起着关键作用。该方法简便、快速、环保,可推广运用于其它一维纳米功能材料的制备。     

合成工艺对水相合成金纳米颗粒的影响

分别采用柠檬酸三钠和硼氢化钠为还原剂在水相中还原氯金酸制备了稳定的金纳米溶胶。通过透射电子显微镜、激光粒度分析仪、紫外-可见分光光度计对所制备的金纳米颗粒的形貌、结构、粒度分布以及光学特性进行表征,研究了还原剂用量、加热反应时间、反应温度、pH值对水相制备金纳米颗粒的影响。结果表明通过调节合成工艺,可以实现金纳米颗粒的可控生长,制备出平均粒径在5～70nm粒度分布均匀的球形金纳米颗粒。     

Synthesis of ZnO nanorods from aqueous solution

In the present work, crystalline one-dimensional ZnO nanorods were synthesized by a PVP (polyvinylpyrrolidone)-assisted hydrothermal process with zinc acetate as the precursor. The major advantage of this technique is the use of water as the solvent: cheaper and more environmentally friendly than alcohol. The as-synthesized ZnO nanorods have diameters of 50-200 nm and lengths up to 5 μm. X-ray powder diffractometry (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), Fourier transmission infrared spectroscopy (FTIR) were used to characterize the structural and the chemical features of the ZnO nanorods.     

Rapid growth of thick particulate film of crystalline ZnO in an aqueous solution

Thick particulate films of crystalline ZnO were developed in an aqueous solution. ZnO crystallized in the solution of zinc nitrate hexahydrate and ethylenediamine at 60 °C. ZnO crystalline particles were then gradually deposited on a glass substrate to form thick particulate films. The thick films were constructed of multi-needle ZnO particles having an ultrafine surface relief structure, and thus had high specific surface area. The thick films can be applied to dye-sensitized solar cells supported by low-heat-resistant polymer films.     

Facile synthesis of ZnO hollow fibres

In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic materials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of cotton fibres was explored. The wall porosity of the ZnO hollow fibres was controlled by changing the concentration of zinc acetate aqueous solution.     

Surfactant assisted solvothermal synthesis of ZnO nanoparticles and study of their antimicrobial and antioxidant properties

This study demonstrated a solvothermal method of growth of three different morphologies of zinc oxide nanoparticles(ZnO NPs): i) flower-like nanorod and nanoflakes, ii) assembled hierarchical structure,and iii) nano granule. Oleic acid(C_(18)H_(34)O_2), gluconic acid(C_6H_(12)O_7) and tween 80(C_(64)H_(124)O_(26)) were used as surfactant/capping/reducing agent for the formation of different morphologies of nanoparticles.The as-synthesized ZnO NPs were characterized by different physicochemical techniques such as UV–vis(UV–vis) spectroscopy, X-ray diffraction(XRD), fourier transform infrared spectroscopy(FTIR), field emission scanning electron microscopy(FE-SEM), energy dispersive X-ray(EDX) analysis and dynamic light scattering(DLS) studies. Further, the antioxidant and antimicrobial activity of these nanostructures was evaluated. The antioxidant activity of these nanostructures was assessed via 2,2-diphenyl,1-1 picrylhydrazyl(DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS) and H_2O_2 free radical scavenging activity. The in vitro antimicrobial activity of the obtained nanostructures was demonstrated against both gram negative(Escherichia coli) and gram positive(Staphylococcus aureus) bacterial genera.This study revealed antioxidant and antimicrobial properties of different structures of ZnO NPs suggesting their biomedical and industrial applications.     

Rapid synthesis of pure and narrowly distributed Eu doped ZnO nanoparticles by solution combustion method

Pure ZnO:Eu³⁺ nanoparticles (~ 50 nm) were prepared by a solution combustion method. ZnO and Eu₂O₃ were used as starting materials and dissolved in nitric acid. Citric acid was used as a fuel. The reaction mixture was heated at 350 °C resulting into a rapid exothermic reaction yielding pure nanopowders. The atomic weight concentration of Eu³⁺ doped in ZnO was 20%. Transmission electron microscopy (TEM) was used to study the particle size and morphology. The nanopowders were characterized for phase composition using X-ray diffractrometry (XRD). Particle size distribution (PSD) analysis of ZnO: Eu³⁺ showed particle sizes ranging from 30 to 80 nm.The photoluminescence emission spectra of ZnO:Eu³⁺ nanostructures showed a strong band emission around 618 nm when excited with 515 nm wavelength.