Microwave irradiation assisted rapid synthesis of Fe-Ru bimetallic nanoparticles and their catalytic properties in water-gas shift reaction

Fe-Ru bimetallic nanoparticles were prepared by a microwave irradiation assisted glycol reduction method using poly-N-vinyl-2-pyrrolidone (PVP) as protective agent. The structure and morphology of the nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDXA) and high-resolution transmission electron microscopy (HRTEM). EDXA and XRD analysis confirmed the presence of Fe and Ru. The bimetallic nanoparticles were subsequently loaded onto an MgAl₂O₄ supporter with K₂O as promoters and used as catalyst for water-gas shift reaction. The results indicated that the FeRu bimetallic nanoparticles exhibit high catalytic activity for water-gas shift reaction due to the synergistic effect between iron and ruthenium. Potassium oxide can enhance the CO selectivity of the catalyst significantly besides increasing the catalyst activity.     

Bicomponent AgCl/PVP nanofibre fabricated by electrospinning with gel-sol method

A new series of poly(vinyl pyrrolidone) (PVP) and silver chloride nanoparticles (AgCl) composite fibres have been synthesized by electrospinning and gel-sol technology. We used sol-gel process to prepare AgCl nanoparticles in the PVP solution, and then the solutions were electrospun to obtain AgCl/PVP composite nanofibres. The final products were thoroughly characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM), which showed the formation of AgCl nanoparticles/PVP composite nanofibres.     

Synthesis,characterization, and dispersion behavior of ZnO/Ag nanocomposites

ZnO/Ag nanocomposites that are composed of quasi-spherical nanoparticles with diameters of several nanometers have been successfully generated by a two-step liquid precipitation method. The as-prepared ZnO/Ag nanocomposites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). The dispersion behaviors of the ZnO/Ag nanocomposites in isopropanol with using nonionic dispersants such as stearic acid, PVP K17, and PVP K30 were investigated by conventional sedimentation method, dynamic light scattering method (DLS) and TEM observation. Both the PVP K17 and PVP K30 could disperse the ZnO/Ag nanoparticles effectively in isopropanol. It is proposed that the nonionic dispersants could form absorbed PVP molecule layers on the surfaces of the ZnO/Ag nanoparticles, prohibiting their agglomeration and enhancing their dispersion stability in isopropanol. This work is helpful for further investigating the potential applications of ZnO/Ag nanocomposites in the fields of medical plastics and sterilization.     

Synthesis of PVP-coated ultra-small Fe3O4 nanoparticles as a MRI contrast agent

Ultra-small Fe₃O₄ nanoparticles were prepared by using the coprecipitation method, in which the polyvinylpyrrolidone (PVP) serves as a stabilizer. The nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), infra spectrum (IR), X-ray photoelectron spectroscopy (XPS) and in vivo magnetic resonance imaging (MRI) test. The results showed that the particles’ size was determined by the dripping rate and that PVP molecules played the role of preventing the aggregation and restricting the size of Fe₃O₄ nanoparticles. The Fe₃O₄ nanoparticles with diameter from 6.5 to 1.9 nm obviously exhibited negative contrast enhancement and concentrated at the target area guided by a permanent magnet.     

静电纺丝法制备金纳米粒子/PVP复合纳米纤维

采用水合肼还原一定浓度氯金酸溶液的方法,在聚乙烯吡咯烷酮(PVP)作保护剂的乙醇/水溶液中,成功制备出粒度较小,且高度分散的金溶胶,紫外吸收光谱证实了溶液中金纳米粒子的存在.采用静电纺丝技术制备了AuNs/PVP复合纳米纤维.采用扫描电镜(SEM)和X射线衍射(XRD)等分析手段对纤维的表面形貌等进行了表征.由扫描电镜...     

Synthesis and characterizations of polycrystalline walnut-like CdS nanoparticle by solvothermal method with PVP as stabilizer

A wide range of cadmium sulfide (CdS) 3D polycrystalline walnut-like nanocrystals were prepared by solvothermal method with polyvinylpyrrolidone (PVP) as stabilizer. The morphology, structure, and phase composition of the as-prepared CdS nanoparticles were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED)). The optical properties of CdS were characterized by photoluminescence (PL) spectra. The paper showed that when the proper dosage of PVP (0.12 g 50 mL⁻¹) and the temperature of reaction (120 °C) were taken, continuous polycrystalline nanoparticles with regular morphology were obtained. The mechanism for the PVP-assisted synthesis of CdS 3D nanostructures and the growth process of CdS nanoparticles via Ostwald Ripening process under different temperatures with different dosages of PVP were also investigated. A sensitive electrochemical detection device of DNA hybridization using a paste glass carbon electrode (GCE) assembled by the PVP-capped CdS nanoparticles and immobilizing DNA probe was developed as a novel application of nano-semiconductors such as CdS to achieve a notable amplification in sensor response.     

Preparation of platinum nanoparticle and its catalytic activity for toluene oxidation

Colloidal Pt nanoparticles are prepared using H2PtCl6 as a precursor, polyvinylpyrrolidone (PVP: molecular weight = 10,000 and 40,000) and hydrogen as a stabilizing agent and a reducing agent, respectively. The amounts of the precursor and the stabilizing agent and the molecular weight of PVP have an effect on the formation of Pt nanoparticles. Supported Pt catalyst (CSPt) is prepared from colloidal Pt nanoparticles and y-Al2O3. Another supported Pt catalyst (ISPt) is prepared by using the conventional incipient wetness impregnation method with an aqueous H2PtCl6 solution and gamma-Al2O3. The catalytic activities of CSPt and ISPt catalysts are compared for VOC (toluene) oxidation. Transmission Electron Microscopy (TEM), UV-vis, X-ray diffraction (XRD) and temperature programmed reduction (TPR) are used to characterize CSPt and ISPt catalysts. The experimental results reveal that the catalytic activity of CSPt is superior to that of ISPT.     

纳米碳包铁磁性颗粒的制备及表征

采用激光感应复合加热蒸发合成法,以CH4为碳源,制备了大量具有壳核结构的纳米碳包铁颗粒,通过透射电子显微镜(TEM)、X射线衍射分析仪(XRD)、能量弥散X射线分析(EDX)等对颗粒进行了表征,并利用动态磁滞回线测定仪测定了纳米颗粒的磁化强度等磁性能.结果表明,利用该方法制备的碳包铁纳米颗粒的平均粒径为25nm,表面碳层厚度为5nm左右,具有铁磁性能.纳米碳包铁颗粒将作为磁性载体在医学细胞分离、细胞染色、靶向用药、定向治疗、肿瘤热疗等方面具有广阔的应用前景.     

Preparation and characterization of dendritic silver nanoparticles

Dendritic silver nanoparticles have been prepared by a soft solution technique from the aqueous solution of silver nitrate and poly (vinyl pyrrolidone) (PVP) in the presence of ethanol used as a reducing agent. The resultant silver nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive analyses of X-ray (EDX), and UV-Visible absorption spectroscopy. It was found that the well-defined dendritic silver nanoparticles which had the length 0.5–1 m and the width of 100–200 nm.     

Formation process of silver nanoparticles in DTAB/SDBS/PVP aqueous solution

Silver nanoparticles were prepared from the nitrate silver solution in dodecyl trimethyl ammonium bromide (DTAB)/sodium dodecylbenzenesulfonate (SDBS)/polyvinyl pyrrolidone (PVP) complex solution with hydrazine as the reductant. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–Vis spectroscopic analysis were conducted to investigate the role of anionic–cationic surfactants on the growth process of silver particles. The results showed that, before the formation of spherical silver nanoparticles, the cube and then tetrakaidecahedrons of AgBr were initially formed. It is concluded that the selective interaction of bow-like electric double-layer structure of anionic–cationic surfactants with certain crystallographic planes of crystals dominated the morphology evolvement of the reaction products. In addition; the PVP coverage finally encouraged the formation of well-dispersed spherical silver nanoparticles.     

Synthesis and characterization of iron aluminide nanoparticles by DC thermal plasma jet

Intermetallic iron aluminide alloy nanoparticles were synthesized by non-transferred DC plasma spray torch at atmospheric pressure. These powder particles were characterized by vibrating sample magnetometer (VSM), X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), laser scattering particle size distribution analyzer, energy dispersive X-ray spectra (EDX) and thermo gravimetric-differential thermal analysis (TG/DTA) studies and the results are discussed. Commercially available iron and aluminium powders in the size range between 40 and 100 μm were ball milled with suitable ratio (Fe-85% and Al-15%) by weight to form a iron-aluminium blende; this was used as feed stock to synthesize iron aluminide nanoparticles. These nanoparticles particles were spherical in shape and black in colour, with the size range between 30 and 70 nm observed by ESEM. It is seen that the powders processed at higher power levels (15.3 kW) have more number of single spherical nanoparticles than powders processed at lower power levels (9.8 kW). The formation of iron aluminide nanoparticles is confirmed by XRD analysis and an exothermic reaction by DTA studies.     

一步法制备L10相FePt纳米颗粒

以乙酰丙酮铁(Fe(acac)3)和氯铂酸(H2PtCl6.6H2O)分别作Fe源和Pt源,三缩四乙二醇(TEG)作溶剂和还原剂,聚乙烯基吡咯烷酮(PVP)作表面活性剂,通过多元醇还原法制备出单分散的FePt纳米颗粒。通过X射线衍射仪(XRD)及透射电子显微镜(TEM)分析表明,所制备的FePt纳米颗粒形状近似球形,分散性较好,平均颗粒粒径约为5.5nm。通过振动样品磁强计(VSM)分析显示所制备FePt纳米颗粒矫顽力为37.64kA/m,这意味着FePt纳米颗粒部分转变为面心四方相(L10相)。     

一种铁纳米材料的制备方法

在常温常压、无任何催化剂的条件下,用电子束辐照法制备纳米铁的前驱体纳米氧化铁,然后用高纯氢还原纳米氧化铁可制得纳米铁.采用X射线衍射仪(XRD)分析试验产物的结构、大小,并用激光衍射粒度分布仪(LSPSDA)观测其粒度分布,可以验证实验效果.介绍了用电子束辐照技术结合高纯氢还原的方法制备铁纳米材料,并探讨了水溶液铁离子的辐射化学反应机理,以及影响纳米氧化铁还原的主要因素.     

聚合物保护纳米镍粉的制备与表征

采用改进的多元醇液相还原工艺,用 1,2 丙二醇作还原剂,在聚乙烯吡咯烷酮(PVP)稳定剂保护下,通过调整反应条件,在均相成核条件下,合成了粒径 25nm,具有面心立方晶体结构的纳米镍粉,运用XRD、TEM、SAED、FTIR 等微观分析手段,研究了NaOH浓度、PVP加入量等因素对制备纳米镍粉的影响。研究发现NaOH可以提高成核速率,调节颗粒生长溶质浓度,是形成粒径均匀纳米颗粒的重要条件。适量的聚合物保护剂,可以阻止成核颗粒生长,减小粒径,防止颗粒团聚,FTIR分析显示PVP分子与纳米颗粒之间存在化学作用。     

Synthesis and Properties of Magnetic Nanoparticles

The uniform mesoporous SBA-15 consisting of SiO2 with long-range channels Offers an excellent host material to synthesize or assemble the magnetic nanocomposites, such as Fe, Ni. In this paper, highly dispersed and uniform iron nanoparticles were incorporated into the pore channels of SBA-15 through a newly developed strategy in which some kinds of coupling agents were used to entrap the nanoparticles into the silica framework. The X-ray diffraction （XRD）, fourier transmission infrared spectroscopy （FTIR）, high-resolution transmission electronic microscopy （HRTEM） and energy dispersive X-ray spectroscopy （EDX） were performed to further identify the successful incorporation and grafting of iron. Compared with other ordinary non-assembled magnetic nanoparticles, the assembled Fe nanoparticles with the diameter even in the size range of 5～6 nm still have better magnetic properties.     

Formation of electrosprayed composite nanoparticles from polyvinylpyrrolidone/mangosteen pericarp extract

Mangosteen pericarp contains a lot of α-mangostin compounds which has very high antioxidant activity. Unfortunately, it has a low solubility in aqueous solution in which for drug delivery application. This paper reports the synthesis of polyvinylpyrrolidone (PVP) nanoparticles loaded with mangosteen pericarp extract (MPE) using the ES method. PVP was trusted as a hydrophilic matrix to carry MPE. The composition of the precursor solution and solution flow rate during the ES process were varied to control the formation of PVP/MPE composite nanoparticles. PVP/MPE composite particles obtained have some wrinkles on their surface and have a geometric average diameter range of 640 to 1534 nm with a geometric standard deviation of 1.35 to 1.65. Increasing the electrical conductivity of the precursor solution resulted in a decrease of nanoparticles' average diameter. Also, the greater the flow rate, the larger the particles formed. The results agreed well with the droplet scaling relations for EHDA by Chen and Pui. Peak shifts in Fourier-transform infrared spectra of PVP/MPE composite nanoparticles indicated hydrogen bond formation between PVP and MPE. It also showed that MPE was successfully encapsulated in PVP matrix. Crystalline peaks of MPE disappear in the X-ray diffraction patterns of PVP/MPE composite nanoparticles, indicating amorphization of MPE after being electrosprayed by PVP. The differential scanning calorimetry study confirmed a hygroscopicity of PVP. The thermogram shows a broad endothermic peak from around 50 to 100 °C as a result of dehydration. In this study, the use of flow rate during the electrospraying process only affected the geometric average diameter, did not change the functional groups, thermal properties, and crystallinity of PVP/MPE particles because they came from the same precursor solution. The results here demonstrate that the ES method can be used for polymeric-nanoparticle-composite production and as an innovation in the field of drug delivery application.     

Shape changes of Pt nanoparticles induced by deposition on mesoporous silica

Polyvinylpyrollidone (PVP)-capped platinum nanoparticles (NPs) are found to change shape from spherical to flat when deposited on mesoporous silica substrates (SBA-15). Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and extended X-ray absorption fine structure (EXAFS) analyses are used in these studies. The SAXS results indicate that, after deposition, the 2 nm NPs have an average gyration radius 22% larger than in solution, while the EXAFS measurements indicate a decrease in first neighbor co-ordination number from 9.3 to 7.4. The deformation of these small capped NPs is attributed to interactions with the surface of the SBA-15 support, as evidenced by X-ray absorption near-edge structure (XANES).     

Introducing CTAB into CdTe/PVP nanofibers enhances the photoluminescence intensity of CdTe nanoparticles

The major objective of this work is focused on the preparation and characterization of the photoluminescence (PL) property of poly(vinyl pyrrolidone) (PVP) embedding CdTe nanoparticles. The CdTe nanoparticles were generated via the reaction of Cd²⁺ with NaHTe and then stabilized by thiolglycolic acid (TGA). In the process of preparing CdTe/PVP nanofibers by electrospinning, a surfactant, cetyltrimethylammonium bromide (CTAB), was introduced to prevent CdTe nanoparticles from congregating inside the PVP nanofibers. Then the results of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) showed that the average diameter of CdTe/PVP nanofibers was 300 (± 61) nm, in which the CdTe nanoparticles were incorporated into the PVP nanofibers homogeneously. Finally, the PL spectra proved that the photoluminescence intensity of CdTe/PVP nanofibers was enhanced by the addition of CTAB.     

Synthesis and characterization of PVP-coated large core iron oxide nanoparticles as an MRI contrast agent

The purpose of this study was to synthesize biocompatible polyvinylpyrrolidone (PVP)-coated iron oxide (PVP-IO) nanoparticles and to evaluate their efficacy as a magnetic resonance imaging (MRI) contrast agent. The PVP-IO nanoparticles were synthesized by a thermal decomposition method and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and a superconducting quantum interface device (SQUID). The core size of the particles is about 8-10 nm and the overall size is around 20-30 nm. The measured r(2) (reciprocal of T(2) relaxation time) and r2? (reciprocal of T2? relaxation time) are 141.2 and 338.1 (s mM)(-1), respectively. The particles are highly soluble and stable in various buffers and in serum. The macrophage uptake of PVP-IO is comparable to that of Feridex as measured by a Prussian blue iron stain and phantom study. The signal intensity of a rabbit liver was effectively reduced after intravenous administration of PVP-IO. Therefore PVP-IO nanoparticles are potentially useful for T(2)-weighted MR imaging.     

One-pot size and shape controlled synthesis of DMSO capped iron oxide nanoparticles

We report here the capping of iron oxide nanoparticles with dimethyl sulfoxide (DMSO) to make chloroform soluble iron oxide nanoparticles. Size and shape of the capped iron oxide nanoparticles are well controlled by simply varying the reaction parameters. The synthesized nanocrystallites were characterized by thermal analysis (TG-DTA), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) for evaluating phase, structure and morphology. ¹H NMR spectra of the synthesized samples confirm DMSO, and the capping of DMSO on the ferrite samples. Shift of the S=O stretching frequency in Fourier transformed infra-red (FTIR) spectra indicates that the bonding between DMSO and ferrite is through an oxygen moiety. The magnetic measurements of all the synthesized samples were investigated with a SQUID magnetometer which shows that the magnetic properties are strongly dependent on the size as well as shape of the iron oxide.