油溶性金属Ni纳米微粒的制备与表征

纳米材料的制备、性能与应用已成为近年来的研究热点之一犤１犦。由于在催化、光学和电学材料中的广泛应用，超细单分散的金属微粒的制备与性质已引起人们的广泛兴趣。通常制备金属纳米微粒的方法有两种：一是把固体金属材料分裂为纳米尺寸的颗粒，如机械粉碎、电弧放电及金属原子蒸气沉积犤２犦，用这种方法制备的金属微粒粒径一般都比较大，且粒子尺寸分布宽，另一种是把金属原子制成纳米尺度的颗粒，如乳液聚合法犤３犦、热解犤４犦、γ－射线辐照犤５犦、脉冲电沉积犤６犦和化学还原犤７犦等，这种方法制备的微粒粒径通常分布窄且粒子小…     

氧化锌-银复合纳米粒子的制备：吸收光谱和荧光光谱

金属和半导体纳米粒子的制备及性质的研究是当今材料科学和物理化学的热门课题［1－6］．在利用太阳能光降解环境污染物、生物传感器以及光生物等方面这些纳米粒子都具有实际应用的可能性．对纳米粒子表面进行修饰而形成的复合纳米粒子可以有效地调整单一颗粒的表面性质甚至颗粒的稳定性．另外，复合纳米粒子的制备对研究纳米粒子的尺寸量子化效应、非线性光学性质及其它光电性质都有重要的意义．人们已成功地制备了许多复合金属－金属纳米粒子，如Cu－Ag［7］，Ag-Pd［8］及Ag－Pt［9］等．关于复合半导体－半导作纳米粒子也有报导，如C…     

介电限域效应对SnO_2纳米微粒光学特性的影响

半导体纳米微粒作为一种新兴材料，在声、光、电、磁、热及催化等方面显示出全新的异于体相材料和分子或原子的特性，在理论和实验上已引起。们极大的兴趣I‘，’］．当纳米微粒的尺寸接近或小于激于玻尔半径时，表现出明显的量子尺寸效应，其表现光学能隙变大，一些半导体粒子如CdS，Cdse等纳米微粒的量予尺寸效应已经被人们利用有效质量近似模型做了定性解释。八但是，由于纳米微粒尺寸小，具有相对大的表面积，因而粒子周围的介质可以强烈地影响它们的光学性质【’，‘1．我们采用胶体化学方法，对SnO。阶电常数为13）半导体纳米微粒…     

半导体纳米粒子的基本性质及光电化学特性

半导体纳米材料因受尺寸量子效应和介电限域效应等特性的影响，往往具有不同于块体材料和原子或分子的介观性质，在材料学，物理学，化学，催化和环保等方面具有广泛的用途，本文介绍了半导体超微粒的基本性质和光电化学特性以及在光能利用方面的应用前景。     

单分散金属介电复合粒子制备及表征研究

过去20年纳米材料科学与技术的飞速发展使人们对于这种新材料寄予极大的期望,合成、组装及设计纳米相材料取得了巨大的进步。一方面单纯的纳米线、纳米杆、纳米晶、纳米管、纳米带、纳米球及量子点材料不断的被报道;另一方面,人们也加大了寻找纳米复合材料的步伐。以二氧化硅等胶体球形粒子为基体发展起来的纳米包覆(nanocoating)技术引起人们的极大兴趣犤1犦。这种纳米包覆技术得到的产物常常被称为核壳粒子(core-shellparticles),通常包括作为核的基体球的表面性质改性与其它材料于表面包覆形成壳层。纳米包覆技术实际上也是粒子表面性质…     

液相分散法制备硬脂酸修饰铋纳米微粒

金属纳米微粒由于具有不同于普通材料的光、电、磁、热力学和化学反应等性能,在催化、信息存储、光电、微电子以及润滑等领域中有着广阔的应用前景。金属纳米微粒这些特殊的物理化学性能主要取决于制备工艺和具体的反应条件,因此研究具有特定性能的金属纳米微粒一直是纳米技术领域中的一个研究热点犤1,2犦,目前制备金属纳米微粒最常用的方法是液相法,它是通过在含有表面修饰剂的溶剂中还原相应的金属盐犤3,4犦或有机金属化合物热分解犤5,6犦来制备表面修饰的金属纳米微粒。虽然这种方法能够制备出多种具有特定性能的金属纳米微粒,但是这种方…     

纳米银的电化学合成

纳米颗粒因具有量子尺寸效应、表面效应和宏观量子隧道效应等不同于晶态体材料和单个分子的固有特性 ,显示出体材料不具备的导电特性、光电特性、光催化能力及随粒径变化的吸收或发射光谱 ,已被用于各种发光与显示装置[1] .其制备的化学方法主要有溶胶 -凝胶法、微乳法、化学沉淀法和醇解法等 [2 ] .近年来 ,新发展出一种电化学合成纳米粒子的方法 ,如 Braun等 [3]利用 DNA模板电化学合成了银纳米线 ,Yu等[4 ] 用电化学合成了金纳米棒 ,Zhu等[5] 利用超声电化学合成了半导体 Pb Se纳米粒子 ,Amigo等 [6 ]用电化学方法合成了 Fe-Sr氧化…     

光电流谱、光致发光光谱和紫外可见吸收光谱在纳米半导体光电器件研究中的联用

在纳米半导体中由于纳米效应(如量子尺寸效应),其电子结构与块体半导体有所不同。进一步地,当纳米半导体与基底和其他组分结合制成器件后,其性质又受到基底或其他组分的影响,这两点导致了基于纳米半导体的光电器件的性能以及相应表征方法也大不相同。将光电流谱、光致发光光谱和紫外可见吸收光谱三种技术有机地结合起来,可以更好地表征纳米半导体的电子性质和光电性能。本文根据纳米半导体材料与电极的电子性质特点及其测量,结合本课题组前期工作,举例介绍三种谱学方法相结合应用于探究光伏电池和电致发光器件的纳米半导体材料的性能,以及纳米半导体材料表面态的表征。     

氧化铁超微粒的光电化学特性

近十年来,。J、粒1（smalParticle）或超微粒f（ultrafinParticle）研究在化学、物理、材料学科等领域中兴起［‘一‘］．超微粒子是指粒径在Inm～几十n－m范围的物质山．快体（如金属、半导体）的性质并不是单个原子或分子本身的性质,而是由许多原子或分子在晶体中的周期排列造成的．当晶体的尺寸在纳米级范围内连续减小时,存在一个从金属或半导体的性质到分子或原子的性质的逐渐过渡．在这个变化范围内,半导体的光学性质有很大变化,金属的电化学行为也发生了变化．这被称为“尺寸量子化效应’．同时当半导体的尺寸在纳米范围时,其…     

乙醇溶液中ZnO纳米粒子的形成机理研究

半导体纳米粒子的研究是当今材料科学及物理化学的热门课题[1－3]．由于纳米粒子具有极大的比表面、尺寸量子化效应及增强的氧化和还原能力等不同于扶林的特殊性质，它被广泛地用于光催化，光电材料的制备及非线性光学材料的研究等[4－6]．ZnO作为一种重要的半导体材料，其纳米粒子的制备近年来也有报导[7－14]．由于ZnO在水中的生成自由能较正，所以一般都在醇溶液中制备，但其具体的成核机理至今并不十分清楚．本工作通过仔细的研究，阐明了ZnO纳米粒子形成过程中的成核和生长机理．1实验部分醋酸锌，氢氧化钠和乙醇均为分析纯试剂．制…     

A Novel Copper Oxide Nanoparticle Conjugated by Thiosemicarbazone Promote Apoptosis in Human Breast Cancer Cell Line

The current study highlights the apoptotic activity of copper oxide (CuO) nanoparticles functionalized by Glutamic acid and conjugated by thiosemicarbazone (TSC) toward human breast cancer (MCF-7) and normal (HEK293) cell lines. To this aim, the co-precipitation method was used for preparation the CuO nanoparticles. Afterward, the CuO nanoparticles functionalized by glutamic acid. After that the functionalized copper oxide nanoparticles (CuO@Glu) conjugated to thiosemicarbazone. In next step, the final nanoparticle product (CuO@Glu/TSC) was characterized by physico-chemical techniques including Fourier transform infrared (FT-IR) spectroscopy, Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), zeta potential analysis and dynamic light scattering (DLS). The effects of in vitro cell viability in CuO@Glu/TSC nanoparticles showed the anti-proliferative properties with a dose-dependent manner (IC₅₀?=?133.97 µg/ml). The IC₅₀ of CuO@Glu/TSC on normal cell line was 230.2 µg/ml. This IC₅₀ deference shows high cytotoxicity of CuO@Glu/TSC nanoparticles on tumor cells and low cytotoxicity on non-tumorigenic cells (HEK293) and is considered as an important aspect for this nanoparticles. Also, CuO@Glu/TSC nanoparticles had efficient effects in inhibiting the growth of breast cancer cell line (MCF-7). In addition, the CuO@Glu/TSC nanoparticle induced apoptosis symptoms which were assessed by Caspase-3 activation assay, Annexin V/ propidium iodide flow cytometry, and Hoechst 33258 staining. Further, Bax and Bcl-2 genes expression was estimated by real time PCR. The expression of Bax increased 1.69 fold, while the expression of Bcl-2 decreased 0.6 fold. The results of the current study propose that CuO@Glu/TSC nanoparticles reveal effective anti-cancer activity against breast cancer cell line.

     

Green synthesis of silver nanoparticles by pepper extracts reduction and its electocatalytic and antibacterial activity

Stable silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, green pepper extract. The aqueous pepper extract was used for reducing silver nitrate. The synthesized silver nanoparticles were analyzed with transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). TEM image shows the formation of silver nanoparticles with average particle size of 20 nm which agrees well with the XRD data. The main advantage of using pepper extract as a stabilizing agent is that it provides long-term stability for nanoparticles by preventing particles agglomeration. To investigate the electrocatalytic efficiency of silver nanoparticles, silver nanoparticles modified carbon-paste electrode (AgNPs–CPE) displayed excellent electrochemical catalytic activities towards hydrogen peroxide (H₂O₂) and hydrogen evolution reaction (HER). The reduction overpotential of H₂O₂ was decreased significantly compared with those obtained at the bare CPE. An abrupt increase of the cathodic current for HER was observed at modified electrode. Also, the antibacterial activity of silver nanoparticle was performed using Escherichia coli and Salmonellae. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.     

Biosynthesis and characterization of lead selenide semiconductor nanoparticles (PbSe NPs) and its antioxidant and photocatalytic activity

The current study fabricated novel lead selenide nanoparticles (PbSe NPs) by a simple biological benign process with Trichoderma sp. WL-Go. Ultraviolet–visible spectroscopy (UV–vis), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transfer infra-red (FTIR) spectroscopic analysis, Raman spectroscopy and Photoluminescence (PL) were used to characterize the physicochemical properties of the fabricated NPs. Synthesis at pH 8 with 0.5 g biomass of strain WL-Go and (1:1) mM of SeO₂: Pb(NO₃)₂ were the optimal synthesis conditions to achieving 10–30 nm cubic faced centered NPs. The PbSe NPs served as catalyst for investigating the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and photodegradation ability of rhodamine B dye (10 mg/L). The results indicated that the NPs could eliminate up to 88.60% of free radicals after adding 600 g/mL NPs and could photodegrade 82% of rhodamine B in 30 min. Thus, this study provides new knowledge and strategies for the future use of an environmentally benign bio- catalytic PbSe NPs to efficiently eliminate free radicals and in treatment of persistent organic pollutants in wastewaters.     

Synthesis of Silver Selenide Bicomponent Nanoparticles by a Novel Technique: Laser–Solid–Liquid Ablation

A novel laser–solid–liquid ablation technique has been developed to synthesize Ag₂Se nanoparticles from silver nitrate and selenium powder in a mixed solvent of 2-propanol and ethylenediamine. The products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The XRD indicated that the products were the single phase of silver selenide. The TEM images revealed that the as-prepared Ag₂Se grains were homogeneous and spherical, and their average size was about 30 nm. This novel technique can be extended to prepare other nanoparticles of various compositions.     

Synthesis and characterization of CdS nanoparticles prepared by precipitation in the presence of span 20 as surfactant

Cadmium sulfide nanoparticles with average size of ≈16 nm have been synthesized using chemical precipitation reaction of CdCl₂ and Na₂S in the presence of nonionic surfactant stabilized reverse emulsions. Sorbian monolaurate (Span 20) is used for the stabilization of emulsions. The influence of Span 20 on controlling the size and properties of CdS nanoparticles were studied. The obtained CdS nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-dispersive x-ray (EDX), and X-ray diffraction (XRD). The optical properties of CdS nanoparticles are investigated systematically by UV-visible absorption spectroscopy. The blue shift in the absorption region and increase in the bandgap to the larger value (2.77 eV) are attributed to the nanosize of the obtained particles.     

SiO2/ZnO复合纳米粒子的制备及表征

采用双注控制沉积法(Controlled Double-Jet Precipitation,CDJP)将反应物添加到含有SiO₂的溶液中,通过直接的表面反应来制备单分散的SiO₂/ZnO复合纳米粒子,并对其进行了表征。透射电镜(TEM)观察表明,SiO₂表面有一层ZnO纳米颗粒或薄层。对复合纳米粒子SiO₂/ZnO进行X射线衍射(XRD)分析,复合颗粒的衍射峰与单独的氧化锌的衍射峰完全一致。能量弥散X射线法(EDX)分析表明,复合颗粒中含有Zn、Si、O元素。荧光光谱表明有ZnO的吸收峰。     

Preparation of Cd-doped SnO<Subscript>2</Subscript> nanoparticles by sol–gel route and their optical properties

Nanocrystalline cadmium doped tin oxide (SnO₂) powders of about 2.5–4.5 nm in size have been synthesized by using different solvents via sol–gel method. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Transmission electron spectroscopy (TEM), UV-Vis absorption and Photoluminescence (PL) spectroscopy. The PL emission spectra revealed that the band centered at 452 nm might be related with oxygen vacancies. A spherical, small rod and slice like morphologies of the prepared Cd-SnO₂ nanoparticles were observed in the SEM and TEM studies. The presence of Cd modifies the structural, morphological and optical properties of the tin oxide nanoparticles.     

Synthesis and structural characterization of sol–gel derived titania/poly (vinyl pyrrolidone) nanocomposites

Non hydrolytic sol–gel method was employed to synthesize pure anatase TiO₂ nanocrystals using tetra isopropyl orthotitanate and poly vinylpyrrolidone as precursors. The structural analyses of the prepared samples were carried out using Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The capping of PVP around TiO₂ nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carbonyl (C=O) and the nanoparticle surface. The XRD, Raman and TEM results indicate that the prepared samples had a pure anatase nano-TiO₂ structure. The particle size analysed by TEM ranged between 7 and 12 nm. The size of the nanocrystals evaluated from the XRD spectra and TEM micrograph is well in agreement. The spacing for the crystal planes was also determined using the ImageJ program applied to the TEM micrographs.     

Characterization of NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles synthesized by various methods

Microwave-induced combustion with glycine, CTAB-assisted hydrothermal process with NaOH and NH3, EDTA assisted-hydrothermal methods have been applied to prepare NiFe₂O₄ nanoparticles for the first time. Structural and magnetic properties of the products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmison electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and electron spin resonance spectrometry (EPR). TEM measurements showed that morphology of the product depends on the synthesis method employed. The average cystallite size of NiFe₂O₄ nanoparticles was in the range of 14–59 nm as measured by XRD. The uncoated sample (Method A) had an EPR linewidth of 1973 Oe, the coated samples reached lower values. The magnetic dipolar interactions existing among the Ni ferrite nanoparticles are reduced by the coatings, which could cause the decrease in the linewidth of the EPR signals. Additionally, the linewidth increases with an increase in the size and the size distribution of nanoparticles.