聚乙烯吡咯烷酮及鞣酸对纳米金制备的影响

在经典Frens法制备金纳米粒子过程中引入聚乙烯吡咯烷酮(PVP)及鞣酸作为保护剂,制备出金纳米粒子并考察了保护剂用量、反应温度和搅拌速度对制备出的金纳米粒子的影响;在制备好的金纳米粒子表面,通过化学还原方法沉积生长银层。利用UV-Vis分光光度计,透射电子显微镜(TEM)等手段对得到的样品进行表征。结果表明:两种保护剂的存在可提高粒子的稳定性、单分散性、粒径分布均匀且在7 nm~25 nm内可控,重现性好;Au/Ag核壳结构复合粒子在适当的摩尔比范围内粒径可控且均匀稳定。     

蔗糖水解制备金纳米粒子的研究

文章报道了一种工艺简单、条件温和、环境友好的绿色制备金纳米粒子的方法。以蔗糖为还原剂,在水解条件下还原氯金酸制备金纳米粒子。采用紫外-可见吸收光谱(UV-Vis)、透射电子显微镜(TEM)、能谱仪(EDX)对合成的金纳米粒子进行表征。实验系统的考察了水解时间、氯金酸添加量、反应时间等制备条件对纳米粒子光学性能的影响。实验结果表明最佳水解时间为20 min,金纳米粒子的粒径随着氯金酸溶液添加量及反应时间的增加而增大。     

W／O微乳液制备纳米粒子的研究

介绍了微乳液的制备方法、微观结构模型和形成理论;介绍了W／O型微乳液在制备纳米粒子方面的应用,并对微乳液法制备纳米粒子的方法、原理、影响因素以及纳米粒子的表征方法进行了重点介绍。     

前沿科研成果融入物理化学实验教学——金-聚丙烯酸铵双面神纳米粒子的合成

设计了一个还原法制备金溶胶,并进一步合成具有双面神结构的金-聚丙烯酸铵纳米粒子的本科生化学实验。首先,采用溶胶法合成金纳米粒子,然后,聚丙烯酸通过异向生长与金纳米粒子形成具有双面神结构的纳米粒子。本实验可以锻炼学生制备纳米材料的能力,熟悉金纳米粒子的制备方法及其纳米尺度的特殊性质,并掌握仪器设备的使用,认识纳米尺度可操控材料的结构,得到金-聚丙烯酸铵双面神纳米粒子,使学生进一步了解科学前沿,提升科学素养。     

微生物角蛋白酶在纳米粒子制备中的应用

金纳米粒子传统制备主要采用物理或化学方法,存在着过程复杂、条件苛刻、化学试剂用量高等缺点,而生物法由于环境友好、作用条件温和等特性逐步受到关注。本研究利用角蛋白酶的还原性制备金纳米粒子,恒温反应,分别对反应过程中氯金酸浓度、酶添加量和反应时间三个因素进行优化,并通过动态光散射（DLS）、zeta电位分析、透射电镜（TEM）及红外吸收光谱（FTIR）对制备的金纳米粒子进行表征。结果表明：在1mmol/L的氯金酸溶液中加入1400U角蛋白酶,反应5h得到的金纳米胶体在550nm左右的吸收峰最显著,反应收率达到85%。红外吸收光谱分析显示3100~3500cm^-1处的酰胺N—H键的不对称伸缩振动峰和1650cm^-1处的酰胺Ⅰ带,证明角蛋白酶本身参与了金纳米粒子的合成,所得纳米金的粒径在30nm以下,zeta电位值为-13mV,粒子之间没有聚集。该方法具有良好的稳定性和可操作性,为金纳米粒子的绿色化制备提供了一种新途径。     

聚酯纳米复合材料研究的进展

利用纳米粒子对高分子材料进行改性可以使其性能更加优异。介绍了共混法、插层复合法等聚酯纳米复合材料的制备方法,讨论了纳米粒子改性聚合物的增韧机理,并对聚酯纳米复合材料的研究进展进行了评述。     

超声法金纳米粒子的制备及结构表征

文章采用超声膜扩散法以氯金酸为原料,用柠檬酸三钠(TSC)在有保护剂PVP保护的条件下还原制备了金纳米粒子。制得的金纳米粒子溶胶采用X射线衍射(XRD)及透射电子显微镜(TEM)等对得金纳米粒子进行表征。结果表明,在本实验条件下制得的金纳米粒子纯度较高,分散性好,基本呈球形,粒径平均尺寸为20nm。     

磁-金纳米粒子的制备及其生物医学应用进展

综述了近年来磁-金纳米粒子的合成及其在生物医学成像诊断和生物医学治疗上的最新应用研究进展。从磁性纳米粒子的制备方法、磁-金纳米粒子的合成方法、磁-金纳米粒子作为成像造影剂用于生物医学多模态成像及“无背景”成像、磁-金纳米粒子作为诊疗一体化探针用于医学诊疗一体化几个方面进行了概述,并对磁-金纳米粒子未来的发展及应用前景进行了展望。     

Au-Fe_3O_4复合纳米粒子的制备及应用进展

院本文综述了多种形态结构的Au-Fe_3O_4复合纳米粒子的制备技术、方法,着重介绍了金磁复合纳米粒子在生物医学领域的应用,并对其今后的研究方向进行了展望。     

不同形貌金纳米粒子的合成与表征

氯金酸水溶液在聚乙烯吡咯烷酮(PVP)存在下,于100℃恒温反应制备得到了不同形貌的金纳米粒子。通过改变PVP浓度、前体氯金酸浓度及反应时间,系统考察了影响不同形貌金纳米粒子生成的各种因素。采用UV-Vis及TEM等方法对金纳米粒子的光学性质及形貌进行了表征。结果表明,降低PVP浓度,提高氯金酸浓度,可以形成"风筝"或"蝌蚪"状等非球形金纳米粒子;提高PVP浓度,降低HAuCl4浓度,可以形成各向同性的球形金纳米粒子。     

活性纳米金颗料在介孔分子筛SBA-15上的分散

Chemical modification （CM） and deposition-precipitation （DP） methods were used for the dispersion of active Au nanoparticles on mesoporous silica materials in this work. XRD, TEM, N2 adsorption isotherms and UV-Vis absorption spectra were used to characterize in detail Au-SBA-15 materials prepared by the two methods. The analysis results showed that high loading （1.7%, by mass） and uniform Au nanoparticles （approximately 3 nm） were dispersed in the channels of mesoporous SBA-15 by the CM method. While for the DP method, most of Au nanoparticles with the size of 10—15nm were aggregated outside of the channels of SBA-15 and the actual loading of Au was only 0.38% （by mass）.     

Preparation of Au/TiO2 catalysts from Au(I)–thiosulfate complex and study of their photocatalytic activity for the degradation of methyl orange

Gold loaded on TiO₂ (Au/TiO₂) catalysts were prepared using Au(I)–thiosulfate complex (Au(S₂O₃)₂³⁻) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S₂O₃)₂³⁻ as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO₂. The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO₂ catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S₂O₃)₂³⁻ precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO₂ catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO₂ and further affects the photocatalytic activity of the obtained catalysts.     

Preparation and Catalytic Activity of Gold–Copper Bimetallic Nanoparticles Stabilized by Poly (N-vinyl-2-pyrrolidone) and Immobilized onto Inorganic Supporters

This paper is devoted to preparation of gold–copper bimetallic nanoparticles deposited on inorganic supporters followed by their use in hydrogen peroxide decomposition and oxidation of ethylbenzene. The bimetallic nanoparticles of Au–Cu at molar ratio of 1:1 were synthesized by hydrothermal method in the presence of stabilizing agent—poly (N-vinyl-2-pyrrolidone) and reducing agent—glycine. The bimetallic nanoparticles were characterized by UV–Vis spectroscopy, DLS, and TEM techniques. The catalytic activity of Au–Cu bimetallic nanoparticles was evaluated with respect to decomposition of hydrogen peroxide and oxidation of ethylbenzene.     

Electrocatalytic activity of carbon-supported Pt-Au nanoparticles for methanol electro-oxidation

Pt-modified Au nanoparticles on carbon support were prepared and analyzed as electrocatalysts for methanol electro-oxidation. In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and Pt-modified Au nanoparticles, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles (∼3.5 nm diameter), Au nanoparticles were supported spontaneously on the surface of carbon black in the aqueous solution. Then a nanoscaled Pt layer was deposited on the surface of carbon-supported Au nanoparticles by the chemical reduction. The structural information and electrocatalytic activities of the Pt-modified Au nanoparticles were confirmed by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and cyclic voltammetry (CV). The results indicate that carbon-supported Au nanoparticles were modified with the reduced Pt atoms selectively. The Pt-modified Au nanoparticles showed the higher electrocatalytic activity for methanol electro-oxidation reaction than the commercial one (Johnson-Matthey). The increased electrocatalytic activity might be attributed to the effective surface structure of Pt-modified Au nanoparticles, which have a high utilization of Pt for surface reaction of methanol electro-oxidation.     

Gold supported on carbon nanotubes for the selective oxidation of glycerol

Gold nanoparticles were supported on multi-walled carbon nanotubes (MWCNTs) by different methods and tested in the selective oxidation of glycerol under basic conditions, with the main purpose of evaluating the effect of the preparation technique on the activity and selectivity. The catalytic performances largely depended on the gold crystallite size. The sol immobilization method was the most suitable technique to prepare gold supported on carbon nanotubes. The use of MWCNTs as support for Au nanoparticles resulted in the oxidation of the secondary hydroxyl group, and therefore, a remarkable high dihydroxyacetone selectivity of about 60% is obtained independently of the preparation method used. A possible explanation based on the peculiar characteristics of the support is proposed. It was also concluded that dihydroxyacetone in the final mixture can be stabilized by lowering the pH to about 3.     

Embedding Ag or Au nanoparticles within the nano-sized wall of YbPO4:Er3+ inverse opals and resulting enhanced upconversion luminescence

Metal nanoparticles preparation in the interior of nanoscale skeleton of inverse opals made up of crystallized matrix is more difficult than the preparation of pure inverse opals. In the present work, the Ag or Au nanoparticles embedded YbPO₄:Er³⁺ inverse opals were prepared by a simple approach, which involved the infiltration of opal template by using the transparent YbPO₄:Er³⁺ sol including silver nitrate or chloroauric acid and the sintering at high temperature. The 20–30?nm Au or 5–10?nm Ag nanoparticles were formed in the interior of nanoscale skeleton in the YbPO₄:Er³⁺ inverse opals, and the Ag or Au nanoparticles embedded YbPO₄:Er³⁺ inverse opals were prepared. The influence of Ag or Au nanoparticles on the upconversion photoluminescence of YbPO₄:Er³⁺ inverse opal was studied, and the upconversion luminescence enhancement induced by the Ag or Au nanoparticles was observed. The mechanisms of upconversion luminescence enhancement of YbPO₄:Er³⁺ inverse opals induced by Ag or Au nanoparticles were discussed. The enhancement of upconversion luminescence induced by Ag nanoparticles was attributed to the enhancement of the excitation field, and the enhancement of upconversion emission induced by Au nanoparticles was related to the increasing of the radiation decay rate of Er³⁺.     

From Molecular Clusters to Metal Nanoparticles

Different methods to prepare supported metal nanoparticles of uniform size are discussed. (i) Supported ruthenium particles were generated from Ru and Ru-Fe bimetallic molecular metal carbonyl cluster precursors (MCC). (ii) Gold nanoparticle formation in the supercage of Y zeolite was studied on Au/NaY, Au/HY and Au-Fe/HY system. (iii) Palladium nanoparticles were grown in liquid phase then deposited on an SiO₂ support or they were grown on the support surface in a solid-liquid interfacial layer. The particle size control was more efficient in the latter two cases than in the preparation starting from MCC.     

Electrodeposition: a versatile and inexpensive tool for the synthesis of nanoparticles,nanorods, nanowires,and nanoclusters of metals

The synthesis of various nanoscale materials, such as nanoparticles, nanowires of Au, Pt, Ni Co, Fe, Ag etc., by electrodeposition techniques have been demonstrated in this article. Both potentiostatic and galvanostatic methods were employed to carry out the electrodeposition process under different potential ranges, time durations, and current densities. The electrochemical behavior of the deposited nanoparticles on various substrates was investigated by cyclic voltammetric and chronoamperometric techniques. The synthesis of mono-dispersed gold (Au) nanoparticles on indium tin oxide (ITO) coated glass, preparation of Au nanorods on nanoporous anodic alumina oxide (AAO), formation of Au nanoclusters on polypyrrole-modified glassy carbon electrode and one-step electrodeposition of nickel nanoparticle chains embedded in TiO₂ etc. have been highlighted in this article. The potential applications of synthesized nanoparticles such as the role of maghemite (Fe₂O₃) in arsenic remediation, higher electrocatalytic activity of Ag nanoclusters for the reduction of benzyl chloride, and the role of C₆₀ nanoparticle-doped carbon film in fabrication processes are also presented in this article.     

Development of fabrication process for metal oxide with nano-structure by the liquid-phase infiltration (LPI) method

To develop a preparation method for size-controlled nanoparticles, we applied a liquid-phase infiltration (LPI) method to the reverse micelle (RM) reaction. The average sizes of the nanoparticles were 4.6 and 2.0 nm for TiO₂ and FeO, respectively. The size distribution was narrow, and particle crystallization was promoted by the nanoscale reaction field. We have also fabricated the TiO₂/Au films with a highly ordered periodic structure by the LPI method using colloidal crystals as a template. The LPI process is conducive to the preparation of advanced nanoceramics with highly ordered structures.     

A novel method for the preparation of bi-metallic (Pt–Au) nanoparticles on boron doped diamond (BDD) substrate: application to the oxygen reduction reaction

A novel method was developed to synthesize bi-metallic nanoparticles (Au–Pt) on boron-doped diamond (BDD) substrate. This method consisted of (a) deposition of a small amount of gold (equivalent to a few monolayers) by sputtering on the BDD surface, (b) heat treatment of the obtained sample at 600 °C in air, resulting in the formation of stable nanoparticles on BDD (Au/BDD electrode), (c) electrodeposition of Pt on the Au/BDD surface occurring preferentially on the Au nanoparticles, and finally (d) heat treatment at 400 °C to enhance the interaction between Au and Pt. The ratio between Au and Pt nanoparticles can be modified by modifying the amount of electrodeposited Pt and was estimated using cyclic voltammetry. These Pt-Au/BDD composite electrodes were used to study oxygen reduction using both potential sweep (cyclic voltammetry) and hydrodynamic (turbine electrochemical cell) methods.