高可见光活性磁性催化剂ZnO/ZnFe_2O_4/石墨烯的制备与表征

以硝酸锌和硫酸亚铁为原料,采用水热法一步合成了ZnO/ZnFe_2O_4纳米颗粒,再通过水合肼还原氧化石墨烯合成了ZnO/ZnFe_2O_4/石墨烯磁性催化剂。采用X射线衍射(XRD),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),傅立叶变换红外光谱仪(FT-IR)等仪器对催化剂的结构进行了表征。以亚甲基蓝作为目标降解物,考察了不同石墨烯掺量的磁性催化剂在可见光照射下的光催化性能。结果表明,当石墨烯掺量为3%时,磁性催化剂的活性最优,可见光照射60min后亚甲基蓝溶液的降解率高达98%。磁性催化剂稳定性良好,且由于ZnFe_2O_4的存在,磁性催化剂可通过外部磁场进行回收。     

Synthesis of spherical NiO nanoparticles through a novel biosurfactant mediated emulsion technique

Spherical nickel oxide nanoparticles were synthesized by microemulsion technique using rhamnolipids as the surfactant along with n-heptane and water. Nickel hydroxide (Ni(OH)₂) particles were first formed which were then calcined to obtain nickel oxide (NiO) particles. Scanning Electron Microscopy (SEM) studies revealed that the synthesized nickel hydroxide particles were spherical in shape with stacked lamellar sheets. Nickel hydroxide was converted to nickel oxide by calcinations at 600 °C for 3 h and was confirmed by X-ray Diffraction (XRD) analysis. Transmission Electron Microscopy (TEM) showed that the nickel oxide particles were crystalline and of uniform size. The effect of pH on particle size was investigated and it was found that the particle size decreased from 86 ± 8 nm at pH 11.6 to 47 ± 5 nm at pH 12.5. A novel method using rhamnolipid biosurfactant for microemulsion synthesis has been demonstrated which offers an eco-friendly alternative to conventional microemulsion technique based on organic surfactants.     

Synthesis and characterization of nanosized Cu/ZnO catalyst by polyol method

Nanosized catalysts composed of metallic copper supported on zinc oxide have been synthesized by the polyol process. Average crystallite size of copper was between 10 and 45 nm. Cu/ZnO catalyst particles were characterized by various techniques, such as X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), and dynamic light scattering analysis (DLS).     

Formation of isolated carbon nanofibers with hot-wire CVD using nanosphere lithography as catalyst patterning technique

Recently the site-density control of carbon nanotubes (CNTs) has attracted much attention as this has become critical for its many applications. To obtain an ordered array of catalyst nanoparticles with good monodispersity nanosphere lithography (NSL) is used. These nanoparticles are tested as catalyst sites in hot-wire chemical vapor deposition (HWCVD) of carbon nanostructures. Aside from using NSL also nickel (Ni) nano-islands are made by thermal annealing of a thin Ni film and tested as catalyst sites. Multiwall CNTs, isolated carbon nanofibres, and other nanostructures have been deposited using HWCVD. Tungsten filaments held at ~ 2000 °C are used to decompose a mixture of ammonia, methane and hydrogen. The structures have been characterized with Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy, Raman spectroscopy and Rutherford Backscattering Spectroscopy.     

Time-dependent growth of CaO nano flowers from egg shells exhibit improved adsorption and catalytic activity

Succulent shaped CaO 3D nano flowers have been synthesized by time growth morphological evaluation from bud-to-blossom using dumped egg shells. A comparative study between commercially available calcium oxide and synthesized CaO nano flowers for adsorptive removal of used engine oil and aldol condensation was conducted. The as-synthesized nano particles were characterized by hydrodynamic particle size analyser, surface area by (BET) Brunauer-Emmett-Teller, XRD (X-ray Diffraction) for crystal structural and SEM-EDX (Scanning Electron Microscopy - Energy Dispersive X-ray) and HR-TEM (High-Resolution-Transmission Electron Microscopy) for morphological examinations. The average size distribution calculated using W-H analysis (1.28–1.38 µm) and morphological studies (1.26–1.30 µm) were in good agreement. The CaO_nsf showed higher adsorption activity for spill oil remediation by dispersion-adsorption method with an extent of separation capacity upto 18 times its weight (18.31 gg⁻¹ of CaO_nsf) in comparison to CaO_cm (8.4 gg⁻¹). The as-synthesized nano flowers displayed excellent catalytic activity for aldol condensation between acetophenone and benzaldehyde. The nano flowers comprising of succulent petals, are formed from many irregular elongated nanospheres. Higher surface area availability leads to higher catalytic activity for production of chalcone with a yield of about 76.3%. This study paves a way for development of CaO based 3D nanostructures, possessing higher adsorption efficiency for oil and an efficient catalyst for base catalysed reactions.     

Effect of reducing agents on the structure of zinc oxideunder microwave irradiation

Zinc oxide was synthesized from zinc sulphate using different reducing agents under microwave irradiation.The influence of sodium borohydride, hydrazine
hydrate and urea on the shape and size of the products were investigated by scanning electron microscopy (SEM) and  X- ray diffraction (XRD). SEM showed the nano-sized spherical and rectangular shaped structures in case of sodium borohydride and hydrazine hydrate, whereas micro-sized hexagonal structures were formed in case of urea under the same irradiation power. The reducing agents played an important role in forming the various structures.
Thus different shapes and size of structures were produced by only varying the reducing agent, which had wide applications in various fields.     

Facile synthesis of rice shaped CuO nanostructures for battery application

The oxides of transition metals are an important class of semiconductors, which have applications in electronics, magnetic storage media, solar applications and catalysis. Among them, CuO has attracted much attention due to its widespread applications. In this paper, a facile synthesis of rice shaped CuO nanostructures have been prepared by reflux method for battery application using Copper nitrate and ammonia as precursors. Samples were prepared at three different reaction timings namely 6, 12 and 24 h. The as-prepared samples were calcinated at 400 °C to ensure the formation of copper oxide. The final products were subjected to X-ray diffraction, scanning electron microscopy, FT-IR and UV–Vis spectroscopy in order to study the effect of reaction time on the properties of the prepared copper oxide nanostructures. It is found that at controlled reaction time rice shaped CuO nanostructures are obtained. Cyclic voltammogram was recorded to understand the electrocatalytic behaviors of the rice shaped CuO sample prepared under optimized condition.     

Mixed-solvothermal synthesis of hybrid nanostructures of alkaline earth phenylphosphonates

Hybrid nanostructures such as nanoflowers, nanosheets and nanoribbons of the alkali earth phenylphosphonates were prepared via mixed-solvothermal approaches by reaction of alkali earth metal salt with phenylphosphonate in ethylene glycol. The final products have been characterized with X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FT-IR), and Thermogravimetry (TG). Effects of reaction parameters on the formation of two-dimensional nanostructure were discussed. This work may provide a simple and effective approach to control the microstructures of the metal phenylphosphonates, which will be of great importance for the controlled synthesis of hybrid nanostructures and further applications.     

The incorporation of preformed metal nanoparticles in zinc oxide thin films using aerosol assisted chemical vapour deposition

The feasibility of Aerosol Assisted Chemical Vapour Deposition (AA-CVD) has been investigated for the growth of zinc oxide (ZnO) films containing preformed metal nanoparticles. The deposition parameters were first established for ZnO thin films, by varying the heating configuration, substrate temperature and deposition time. Films were characterised using Scanning Electron Microscopy and X-Ray Diffraction. As-deposited films, grown at 250 °C, were mostly amorphous and transformed to highly crystalline Wurtzite ZnO at higher substrate temperatures (400-450 °C). A change in the preferential orientation of the films was observed upon changing (i), the substrate temperature or (ii), the heating configuration. Following this, the applicability of the AA-CVD process for the incorporation of preformed nanoparticles (platinum and gold) in ZnO thin films was investigated. It was found that surface agglomeration occurred, such that the ZnO films were capped with an inhomogeneous coverage of the metal. These layers were characterised using Transmission Electron Microscopy and Electron Diffraction. A possible mechanism for the formation of these metal surface clusters is presented.     

Low temperature reduction route to synthesise bismuth telluride (Bi2Te3) nanoparticles: structural and optical studies

Herein, we report the synthesis of highly yielded bismuth-telluride (Bi₂Te₃) nanoparticles at 50 °C by direct wet chemical route in which the bismuth and tellurium precursors have been dissolved in deionised water, ethylene glycol and hydrazine hydrate. This method is very facile, inexpensive and less hazardous and ensures almost complete yield of the precursors. The powder product was well characterised by powder X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray diffraction, transmission electron microscopy and scanning electron microscopy. It is investigated that the synthesised powder has a rhombohedral structure of Bi₂Te₃ with average diameters of the particles about 35 nm. Thus, the synthesis process has been modified to design nanostructures of thermoelectric materials with related crystal structures.     

Cu and CuO nanostructures: facile hydrothermal synthesis,characterization and photocatalytic activity using new starting reagents

The present investigation reports a simple hydrothermal process for synthesizing Cu and CuO nanostructures using new set of low-cost starting reagents including CuSO₄·5H₂O, ethylenediamine and hydrazine hydrate. The obtained nanostructures were characterized by techniques such as XRD, SEM, EDX, DRS and FTIR. Effect of hydrazine hydrate, ethylenediamine, reaction temperature and time on morphology of prepared nanostructures was well studied. Our results showed ethylenediamine and hydrazine hydrate play crucial role on particle growth, formation mechanism of nanostructures and consequently on morphology of nanostructures. Furthermore, the efficiency of CuO nanostructures as a photocatalyst for the decolorization of methylene blue using ultraviolet light irradiation was evaluated and the CuO nanoparticles compared to nanorods showed more efficient photocatalytic activity.     

In-situ fabrication of AAO template without oxide barrier layer and its applications

Porous anodic aluminum oxide (AAO) film is the most widely used template in combination with electrodeposition (ED) method to fabricate one-dimensional nanostructures such as nanowires, nanotubes and nanorods. However, the existing oxide barrier layer after the anodization blocks the application of AAO template in synthesis of nanostructures via direct electrodeposition. In this paper, AAO template without oxide barrier layer was successfully fabricated by stepwise voltage decrement; influence of two types of stepwise voltage decrement on the removal of oxide barrier layer was introduced. Field Emission Scanning Electron Microscopy (FESEM) images indicated that stepwise voltage decrement could make the oxide layer thin effectively. Meanwhile, highly ordered gold nanowire arrays were fabricated by using direct electrodeposition method based on AAO template with the second anodization process with stepwise voltage decrement of 1 V/min, FESEM image showed that as-prepared gold nanowires are uniform in diameter and the diameter is in accordance with the diameter of AAO template pores. XRD pattern revealed that gold nanowires were indexed as face-centered cubic phase.     

A novel route for the synthesis of nanotubes and fullerene-like nanostructures of molybdenum disulfide

The paper described the synthesis of nanotubes and fullerene-like nanostructures of MoS₂ through a technically simple, rapid, and energy-efficient microwave-assisted synthesis technique, which involved the use of elemental sulfur dissolved in a mixture of monoethanolamine and hydrazine hydrate as the sulfide source. The microwave induced reaction between the molybdate with sulfide ions, in the presence of hydrazine hydrate in the reaction medium, resulted in the formation of gray colored powders of amorphous MoS₂. The as-obtained powders were calcined at 600 °C for 2 h and characterized by different techniques. HRTEM analysis of the calcined samples indicated the formation of fullerene-like MoS₂ structures when the starting solution mixture was irradiated with microwave for a period of 200 s, while on 600 s of irradiation of the same revealed the formation of folded sheets like MoS₂ nanotubes. BET surface areas of the calcined samples have been measured and a plausible reaction mechanism for the formation of nanotubes and fullerene-like nanostructures of MoS₂ has been proposed.     

Green synthesis and characterization of hexagonal shaped MgO nanoparticles using insulin plant (Costus pictus D. Don) leave extract and its antimicrobial as well as anticancer activity

Green synthesis is an ecofriendly novel technology and attractive research area for the production of metal oxide nanoparticles in bio-medical and chemical applications. The green perspective includes solvents, reductants or stabilizing agents obtained from a natural resource as they are non-toxic and ecofriendly. In this study, a sustainable green synthetic strategy to synthesize magnesium oxide nanoparticles by employing Costus pictus D. Don plant leaf extract as a reducing agent. The successful formation of magnesium oxide nanoparticles was confirmed by comprehensive characterization techniques. The presence of biomolecules and metal oxides were confirmed by Fourier transform Infrared (FT-IR) spectral data analysis. The X-ray diffraction (XRD) revealed the formation of pure cubic MgO crystalline nanoparticles. The surface morphology of MgO particles observed by Scanning electron microscope (SEM) showed the hexagonal-shaped MgO crystallites. The average size of biosynthesized MgO nanoparticles was measured to be around 50?nm by Transmission Electron Microscopy (TEM). The mechanism for the formation of MgO nanoparticles was suggested in this study. The biosynthesized magnesium oxide particles showed good antimicrobial and exhibited maximum inhibition rate for MgO nanoparticles at 200?µg showing efficient anticancer activity.     

Facile synthesis and characterization of flame retardant viscose fiber via graft copolymerization and chemical modification

A new strategy for synthesizing flame retardant viscose fiber (FR-VF) has been achieved by graft copolymerization of acrylonitrile (AN) onto viscose fiber and the subsequent chemical modification with hydrazine hydrate and zinc acetate. The structure of FR-VF was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrometry (FTIR). The surface morphology of FR-VF was analyzed using scanning electron microscope (SEM). The results show that the graft copolymerization of AN onto viscose fiber and the reaction of VF-g-PAN with hydrazine hydrate and zinc acetate have been successfully carried out. The thermal properties tested by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques show that the thermal degradation rate of FRVF is slower than that of untreated FR-VF after 300°C. As a result, the char residue increases from 5.2% to 50.4% at 800°C. Furthermore, the burned FR-VF keeps original form as evidenced by SEM analysis, indicating that the obtained FR-VF possesses excellent thermal stability and char forming capability.     

The Role of Boron Nitride in Graphite Plasma Arcs

Novel graphitic nanostructures (e.g. nanotubes, graphitic onions, polyhedral particles, hemitoroidal nanotube caps and branched nanotubes) are produced by arcing graphite electrodes, containing hexagonal-BN, in inert atmospheres. The introduction of BN or B inside the graphite anode generates long (≤ 20μm) and well graphitised carbon nanotubes exhibiting boron at their tips. High Resolution Electron Microscopy (HRTEM), Scaning Electron Microscopy (SEM), Electron Energy Loss Spectroscopy (EELS) and X-ray powder diffraction studies reveal the production of B₄C crsytals, in addition to little amounts of BC₃ nanotubes. Mass spectrometry (MS) studies over the generated soots indicate high yields of large fullerenes (e.g. C₇₀, C₇₆, and C₈₄) and thermo-Gravimetric analysis (TGA) of the nanostructures show high oxidation resistance.     

Effect of boron incorporation on the structure and electrical properties of diamond-like carbon films deposited by femtosecond and nanosecond pulsed laser ablation

The influence of the incorporation of boron in diamond-like carbon (DLC) films on the microstructure of the coatings has been investigated. The boron-containing DLC films (a-C:B) have been deposited by pulsed laser deposition (PLD) at room temperature in high vacuum conditions, by ablating graphite and boron targets either with a femtosecond pulsed laser (800 nm, 150 fs, fs-DLC) or with a nanosecond pulsed laser (248 nm, 20 ns, ns-DLC). Alternative ablation of the graphite and boron targets has been carried out to deposit the a-C:B films. The film structure and composition have been highlighted by coupling Field Emission Scanning Electron Microscopy, Electron Energy Loss Spectroscopy and High Resolution Transmission Electron Microscopy. Using the B K-edge, EELS characterization reveals the boron effect on the carbon bonding. Moreover, the plasmon energy reveals a tendency of graphitization associated to the boron doping. Pure boron particles have been characterized by HRTEM and reveal that those particles are amorphous or crystallized. The nanostructures of the boron-doped ns-DLC and the boron-doped fs-DLC are thus compared. In particular, the incorporation of boron in the DLC matrix is highlighted, depending on the laser used for deposition. Electrical measurements show that some of these films have potentialities to be used in low temperature thermometry, considering their conductivity and temperature coefficient of resistance (TCR) estimated within the temperature range 160-300 K.     

ZnO nanoparticles and porous coatings for dye-sensitized solar cell application: Photoelectrochemical characterization

Nanoscale zinc oxide (ZnO) powder with Brunauer-Emmelt-Teller surface area of 43 m² g^− 1 has been synthesized by soft chemistry at low temperature via reaction of zinc acetate dehydrate (Zn(CH₃COO)₂.2H₂O) and sodium hydroxide (NaOH). The influence of the pH value of the sol on the structure and morphology of ZnO powder have been investigated by X-Ray Diffraction, Scanning Electron Microscopy and High Resolution Transmission Electron Microcopy. Their thermal properties have been determined by simultaneous Differential Thermal Analysis and Thermogravimetry coupled to Mass Spectroscopy analysis. The nanoparticles are single crystals with (101) preferred orientation but agglomerated. Their crystallite size can be adjusted from 15 nm to 35 nm by controlling the pH value between 7 and 13. Thick porous crystalline coatings have been obtained by doctor blade coating on conducting SnO₂:F glass substrates using pastes prepared by wetting the crystalline powders with polyethylene glycol and water. After sintering at 400 °C and Ruthenium 535 dye sensitization, the coatings have been tested in a three electrode electrochemical cell containing an appropriate electrolyte in the dark and under 450 W Xenon lamp illumination. The influence of the electrolyte iodine concentration, the film thickness and the light intensity on the current density are presented and discussed. Such coatings appeared promising for the realization of dye sensitized solar cells.     

A wet chemistry method for the construction of silver nanosandwichs using laponite clays

Herein, we report a method for the construction of new silver nanostructures in aqueous solution with potential applications as nanocapacitors. A synthetic clay composed of disk-shaped particles of approximately 30 nm in diameter and 1 nm thickness, called laponite, was treated with activated Ag solution and allowed to react overnight to form silver nanodisks on each face of the clay in a sandwich assembly. The products of this reaction were analyzed by Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy.     

A one-step hydrothermal way for the synthesis of vanadium oxide nanotubes containing the phenylpropylamine as template obtained via non-alkoxide route

Vanadium oxide nanotubes (VO_x-NTs) with high crystallinity were synthesized by using the crystalline V₂O₅ as precursor for the first time with 3-phenylpropylamine as structure-directing template via one-step hydrothermal way. Structure and morphology of the nanotubes were investigated by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray powder diffraction, Thermal analysis and Infrared. The inner and the outer of the obtained nanotubes vary respectively between 15 to 25 nm and 70 to 100 nm with a length up to 4 μm.