ZnO晶面对纳米Au催化CO氧化性能的影响

采用水热合成法制备了无择优暴露晶面的盘状ZnO（ZnO-D）和优先暴露（100）非极性面的片花状ZnO（ZnO-F）;通过沉积-沉淀法将Au纳米颗粒负载于所制备的ZnO载体表面;采用ICP、XRD、SEM、TEM、XPS和BET对合成的催化剂进行表征;最后,以CO氧化为探针反应研究载体晶面对金纳米颗粒催化性能的影响。结果表明,ZnO形貌对Au颗粒粒径影响甚微,但Au物种的电子价态表现出显著的载体形貌依赖性。以盘状和片花状ZnO为载体所获得的金催化剂的Au^δ+物种的原子分数分别为34.8%和67.4%,说明Au颗粒与片花状ZnO间具有更强的金属-载体相互作用。Au/ZnO-F催化剂的CO氧化活性明显优于Au/ZnO-D,归因于Au/ZnO-F具有较高的O₂吸附活化能力。本文通过调控载体形貌/晶面进而调变金属-载体间相互作用及Au物种的化学态的方法提高了Au催化性能。     

Au/Fe3O4纳米复合材料的制备及其催化性能

通过将金纳米粒子铆接到Fe3O4载体表面,制得了Au/Fe3O4纳米复合粒子。首先以对苯二酚为还原剂还原HAuCl4制得球形金纳米粒子;然后采用溶剂热法制备Fe3O4磁性纳米颗粒,并用巯基丙酸(MPA)对其修饰;最后通过MPA与金纳米粒子之间的相互作用,将金纳米颗粒固定到Fe3O4表面。采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)和振动样品磁强计(VSM)和紫外-可见分光光度计(UV-vis)对所制备材料进行形貌、晶型、磁性和催化性能的表征。结果表明,金纳米颗粒成功包覆在Fe3O4表面,所得到的Au/Fe3O4复合纳米材料具有单分散性和超顺磁性,并且对NaBH4还原对硝基苯酚(4-NP)制备对氨基苯酚(4-AP)的反应显示出优良的催化性能。     

基于雪花形状的金纳米结构的抗坏血酸传感器的研究

本文利用一步合成装技术在碳纸表面合成雪花片形状的金(Au)纳米结构通过控制聚乙烯亚胺和Au纳米颗粒的浓度和反应时间。利用聚乙烯亚胺上的N与Au形成N-Au纳米颗粒组装成雪花形状Au纳米结构。用扫描电镜来表征雪花形状Au纳米结构的形貌,Au纳米结构很均匀的分散在碳纸表面,并不存在大的团聚。电化学技术(循环伏安法和计时电流分析法)检测雪花形状Au纳米结构对抗坏血酸的响应情况,显示修饰电极对抗坏血酸有很好的响应,在抗坏血酸浓度1×10~(-6)~1.15×10~(-4) mol/L的范围内,氧化电流与其浓度存在线性关系(R=0.998),检测限为6×10~(-7) mol/L;另外传感器具有很好的稳定性和选择性,为小分子污染物的检测提供新方法。     

制备条件对Au/TiO_2液相氧化反应活性的影响

采用沉积-沉淀法制备纳米级Au/TiO_2催化剂,以葡萄糖液相催化氧化制葡萄糖酸为探针反应,考察了催化剂制备条件对Au/TiO_2活性的影响,并利用TEM、XRD和XPS等方法对催化剂进行了表征。结果表明,Au/TiO_2对葡萄糖液相氧化反应的催化活性与催化剂的制备条件密切相关,纳米金的颗粒尺寸不是决定催化活性的惟一因素,金在催化剂中的价态对催化活性有重要影响。     

细菌纤维素负载金纳米粒子复合膜的制备及催化性能

以细菌纤维素(BC)为基底,氯金酸(HAu Cl4)为金前驱体,通过原位还原法制备了BC负载金纳米粒子(Au NPs)复合膜。采用紫外-可见光谱仪、透射电子显微镜、X射线衍射仪、电感耦合等离子发射光谱仪和傅里叶变换红外光谱仪对复合膜的结构和性质进行了表征,并通过对硝基苯酚(4-NP)催化还原反应来评价Au NPs-BC复合催化剂的催化性能。研究结果表明:复合膜上Au NPs的粒径大小为(5.30±1.23)nm,其反应速率常数高达5.09×10-3s-1,Au NPs-BC催化剂表现出优异的催化活性及重复稳定性。     

404有机担体负载磷钨酸催化芳香醛与1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮的缩合反应

合成了形貌具有典型立方晶型结构的404有机担体负载磷钨酸,用这种新型负载型催化剂催化芳香醛与1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮的缩合反应,共合成了6种未见文献报道的吡唑啉酮衍生物,产物通过IR,1HNMR和元素分析表征。研究发现,404有机担体负载磷钨酸催化剂具有稳定的空间结构,分散性好,负载量稳定,对催化此类反应具有催化产率高、催化反应时间短、选择性高、不污染环境和催化剂能够重复利用等特点。     

金-氧化硅核-壳结构复合球的制备

采用商用金溶胶(颗粒大小约20nm．金的质量分数为0．01％)和正硅酸乙脂为先驱物，以氨水为催化剂，用H2N(CH2)3Si(OCH3)3和HSCH2CH2OH作为金的表面改性剂，制备金纳米颗粒的氧化硅包层，以获得金-氧化硅(Au—SiO2)核-壳结构的复合球。用透射电子显微镜(transmission electron microscope，TEM)研究复合颗粒的大小和形状及氧化硅对金颗粒的包敷情况。实验表明：同时使用2种表面改性剂，可制备出球心只含1个金纳米粒子的Au—SiO2核-壳结构复合球(大小约200nm)。要获得单分散的Au—SiO2核-壳结构的复合球，还需要对优化制备工艺条件进行深入研究。     

[Bmim]FeCl4中金纳米材料的合成及其催化性能

在1-丁基-3-甲基咪唑四氯化铁盐([Bmim]FeCl4)中用油胺还原AuCl3制备了2种金纳米材料,研究了产物的形貌特征,考察了所制纳米材料催化NaBH4还原对硝基苯酚制备对胺基苯酚的性能.结果表明,产物形貌主要由[Bmim]FeCl4/油胺摩尔比决定,比值从0.5增至2,金纳米材料从枝状结构转变成花状结构,长径比约为10的棒变为径向长度200nm的片层;枝状纳米颗粒比花状纳米颗粒的催化性能好.     

活性炭负载12-磷钨酸催化合成柠檬酸三丁酯

采用超声波浸渍法制备了活性炭负载12-磷钨酸催化剂,并通过红外光谱、X-射线衍射、N2吸附-脱附和SEM等方法对其进行表征。以柠檬酸三丁酯的合成为探针反应,评价该催化剂的活性。结果表明,磷钨酸负载到活性炭后保持了原有的Keggin结构;在磷钨酸负载量为25%、催化剂占酸醇总质量的7 wt%、n(柠檬酸)∶n(正丁醇)=1∶4、回流时间为4 h的条件下,酯化率可达97.6%。催化剂重复使用5次,仍具有较高的活性。     

双羟基金属氢氧化物负载的金催化剂的稳定性

以3种层板组成的层状双羟基金属氢氧化物(layered double hydroxides,LDHs)为载体,制备了负载型金催化剂样品(Au/MgAl-LDHs,Au/ZnAl-LDHs和Au/MgFe-LDHs),借助X射线衍射、透射电子显微镜和光电子能谱,表征了金催化剂样品的物性,研究了催化剂样品在CO常温催化氧化反应中的活性及稳定性。结果显示,LDHs载体表面的金以金属态存在,其粒径1~5 nm,在常温下,金催化剂对CO的转化率达100%。另外,金催化剂在使用过程中失活的主要原因是载体晶体结构不稳定:晶体结构的坍塌使载体表面的纳米金颗粒被覆盖,导致表面金含量降低而失活。此外,LDHs的层状结构坍塌也削弱了载体与纳米金颗粒之间的相互作用,使得纳米金颗粒因迁移、聚集、长大而失活。催化剂的稳定性顺序由大到小依次为Au/MgAl-LDHs,Au/ZnAl-LDHs和Au/MgFe-LDHs,稳定性的差异与LDHs层板的电荷密度有关,电荷密度最大的MgAl-LDHs负载的金催化剂稳定性最高,连续使用69 h后,CO的常温转化率仍能保持100%。     

Tunability and stability of gold nanoparticles obtained from chloroauric Acid and sodium thiosulfate reaction

ABSTRACT: In the quest for producing an effective clinically relevant therapeutic agent, scalability, repeatability, and stability are paramount. In this paper, gold nanoparticles (GNPs) with precisely controlled near infrared (NIR) absorption are synthesized by a single step reaction of HAuCl4 and Na2S2O3, without assistance of additional templates, capping reagents or seeds. The anisotropy in the shape of gold nanoparticles offers high NIR absorption making it therapeutically relevant. The synthesized products consist of GNPs with different shape and size, including small spherical colloid gold particles and non-spherical gold crystals. The NIR absorption wavelengths and particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. Non-spherical gold particles can be further purified and separated by centrifugation to improve the NIR absorbing fraction of particles. In-depth studies reveal that GNPs with good structural and optical stability only form in a certain range of the HAuCl4/Na2S2O3 molar ratio, whereas higher molar ratios result in unstable GNPs, which lose their NIR absorption peak due to decomposition and reassembly via Ostwald ripening. Tuning the optical absorption of the gold nanoparticles in the NIR regime via a robust and repeatable method will improve many applications requiring large quantities of desired NIR absorbing nanoparticles.     

Synthesis of stable AuAg bimetallic nanoparticles encapsulated by diblock copolymer micelles

We present a facile method for the preparation of bimetallic AuAg nanoparticles (NPs) with controlled size and composition rendering them ideally suitable for optical and catalytic applications. In analogy to methods for the generation of monometallic Au and Ag NPs, AuAg NPs were prepared inside polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block-copolymer micelles formed in toluene, by loading the P4VP cores of the micelles first with AgNO(3) and then with HAuCl(4). In contrast to the reverse sequence of loading, homogenously bimetallic AuAg particle arrays were achieved after reduction carried out in solution with hydrazine monohydrate as the reducing agent. TEM reveals that stable and spherical NPs can be prepared well separated from one another and with a narrow size distribution with diameters of ～3 nm. The bimetallic NP composition was confirmed by energy-dispersive X-ray spectroscopy (EDX) of single NPs. The atomic ratio of Ag and Au contained in single particles is in good agreement with the relative concentrations of both metals used in the synthesis which was confirmed by atomic absorption spectroscopy. The atomic ratio Au?:?Ag was systematically varied between 3?:?1 and 1?:?3. For all ratios UV-vis spectra showed a single plasmon band. Its wavelength varied from 430 for Au?:?Ag = 1?:?3 to 515 nm for Au?:?Ag = 3?:?1, showing a linear dependence on the relative amount of gold within the range of plasmon wavelengths from monometallic gold (538 nm) to silver (415 nm).     

Synthesis and characterization of Au/TiO2 core-shell structure nanoparticles

Au/TiO₂ core-shell structure nanoparticles were synthesized by sol-gel process, and the morphology and crystallinity of TiO₂ shell were investigated by TEM and UV-vis absorption spectrometer. Au/TiO₂ core-shell structure nanoparticles could be prepared by the hydrolysis of TOAA (titanium oxide acethylacetonate) in gold sol ethanol solution with water. The thickness of TiO₂ shell on the surface of gold particles was about 1 nm. To investigate the crystallinity of TiO, shell, UV light with 254 nm and radioactive ray of⁶⁰Co were irradiated on the TiO₂-coated gold sol ethanol solution. The surface plasmon band of gold nanoparticles appeared only when the radioactive ray was irradiated on the TiO₂-coated gold sol ethanol solution. From these results, it was found that the TiO, shell was amorphous and the MUA (mercaptoundecanoic acid) layer on the Au particle for its dispersion in ethanol did not act as an obstacle to disturb the movement of electrons onto the surface of Au particles.     

Synthesis of patterned nanogold and mesoporous CoFe2O4 nanoparticle assemblies and their application in clinical immunoassays

Herein, we describe a facile and feasible synthesis method for patterning nanogold particles onto magnetic mesoporous CoFe(2)O(4) nanostructures (Au-MMNs) by using poly(vinyl pyrrolidone) (PVP) as cross-linker. Initially, mesoporous CoFe(2)O(4) nanoparticles were initially synthesized with a thermal decomposition method by using mesoporous silica nanoparticles as templates, and then nanometre-sized gold particles were produced through the in situ reduction of the Au(III) on the PVP-functionalized CoFe(2)O(4). The as-prepared Au-MMNs were characterized by transmission electron microscopy (TEM), N(2) adsorption-desorption isotherms, UV-visible adsorption spectrometer, vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Furthermore, we also demonstrate the conjugation capacity of the synthesized Au-MMNs toward biomolecules by using quartz crystal microbalance (QCM), and the possible application in the electrochemical immunoassays. Experimental results indicated that the resulting Au-MMNs display good conjugation capability toward the biomolecules, and excellent analytical properties for determination of target molecules.     

一种金纳米粒子制备及表征研究

以氯金酸和葡萄糖为原料,柠檬酸钠为保护剂,成功制备出金纳米粒子,并应用透射电镜和紫外-可见分光光度计对该实验样品进行了表征,结果表明此类纳米粒子尺寸均匀、呈球形单分散分布。并讨论了不同因素对粒子尺寸的影响。     

One-pot synthesis of PdAu bimetallic composite nanoparticles and their catalytic activities for hydrogen peroxide generation

We report a facile one-pot aqueous-phase synthesis of PdAu bimetallic nanoparticles with different Pd/Au ratio. The synthesis was conducted by co-reduction of Pd and Au precursor using ascorbic acid as a reducing agent and in the presence of polyallylamine hydrochloride (PAH). By high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectrometry (EDS) analyses, we found that the synthesized nanoparticles had an onion-like core/shell/shell/shell structure with Au-rich core, Pd-rich shell, Au-rich shell, and Pd shell, respectively. We also investigated the catalytic performance of the synthesized PdAu nanoparticles toward hydrogen peroxide generation reaction.     

Au-Cu复合纳米粒子的制备及其电催化性质

在PEG6000/Vc/HAuCl4体系中,利用Vc还原HAuCl4制备了金纳米粒子,以制备的金纳米粒子为晶种,用水合肼还原硫酸铜制备了Au-Cu复合纳米粒子,并用紫外-可见光谱(Uv-vis)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)、选区电子衍射(SAED)对其进行表征。用循环伏安法研究Au-Cu复合纳米粒子修饰的玻碳电极对H2O2电化学氧化的催化作用,实验结果表明,Au-Cu复合纳米粒子对H2O2电化学氧化具有一定的催化活性。     

A general and efficient method for decorating graphene sheets with metal nanoparticles based on the non-covalently functionalized graphene sheets with hyperbranched polymers

Multipyrene terminated hyperbranched polyglycidol (mPHP) has been synthesized and used to non-covalently functionalize pristine graphene sheets (GSs) through π-π stacking interactions. Mediated by the mPHP layer, a variety of metal nanoparticles (Au, Ag and Pt) were in situ generated and deposited onto the surface-modified GS, yielding versatile GS/mPHP/metal nanohybrids. As typical examples, by simply controlling the concentration of HAuCl(4) used, Au nanostructures ranging from isolated spheres to a continuous film were created and coated onto the surface-modified GS. The studies on the fluorescence properties of resulting GS/mPHP/Au hybrid nanostructures reveal that the GS and controllable content of Au components in the hybrids can effectively quench the fluorescence emission of mPHP in a controlled manner. Further investigation indicates that GS/mPHP/Au hybrids are promising surface enhanced Raman scattering (SERS) substrates. The SERS activities of these hybrids depend on the contents and form of the Au. The GS/mPHP/Au hybrid containing continuous Au films exhibits the strongest SERS activity. GS/mPHP/Au hybrids are also used as efficient heterogeneous catalysts for the reduction of 4-NP, and demonstrate excellent catalytic performance. The detailed reaction kinetics and the reusability of such catalysts have also been investigated.     

Growth and branching of gold nanoparticles through mesoporous silica thin films

Composite materials made of mesoporous oxide thin films containing metallic nanoparticles are of high interest in various fields, including catalysis, biosensing and non-linear optics. We demonstrate in this work the fabrication of such composite materials containing a sub-monolayer of gold nanoparticles (GNPs) of various shapes covered with mesoporous silica thin films. Additionally, the shape of the GNPs (and thus their optical properties) can be modified in situ through seeded growth and branching. Such growth proceeds upon wetting with HAuCl(4) solution, a surfactant (cetyltrimethylammonium bromide, CTAB) and a mild reducing agent (ascorbic acid, AA). The effect of varying several reaction parameters (time and CTAB and AA concentrations) was evaluated, showing that more anisotropic particles are obtained at longer reaction times, lower CTAB concentration and higher AA concentration. The final shape of the GNPs was also found to depend on their initial shape and size, as well as the pore size of the mesoporous film covering them. Because the growth proceeds through the pores of the film, it may lead to shapes that are not easily obtained in solution, such as particles with branches on one side only. Finally, we have confirmed that no damage was induced to the mesoporous silica structure during the growth process and thus the final particles remain well covered by the thin film, which can eventually be used as a filter between the GNPs and the outer medium.     

Rapid microwave-assisted synthesis of gold loaded hydroxyapatite collagen nano-bio materials for drug delivery and tissue engineering application

A rapid microwave assisted facile synthetic technique was adopted to load gold nanoparticles (Au) on hydroxyapatite (HAp) surface. HAp nanoparticles were primarily synthesized by wet precipitation technique and further used for gold loading and successive collagen coating for biomedical applications. The microwave-assisted controlled synthesis technique with three heating cycles allows the very fast growing of Au seeds over HAp facets. Different sophisticated analytical techniques and spectroscopic characterization were employed to confirm the structural, chemical, and morphological features. The synthesized different concentration “Au” loaded hetero nanostructures coated with collagen (Au–HAp–Col) optimized for drug (Doxorubicin: DOX) loading and releasing purposes for biomedical applications. The maximum drug-loading efficiency of ~58.22% and a pH responsive releasing of ~53% (at pH 4.5) was obtained for 0.1?wt% Au–HAp–Col nanoparticles. To study the cytotoxic effects from the hetero nanostructures, MG-63 osteoblast-like cells were exposed to different concentration ranges on Au–HAp, Au–HAp–Col, and DOX loaded Au–HAp–Col nanoparticles. The non-toxic and bioactive properties of the synthesized nanoparticle-fabricated scaffold promotes cellular attachment, growth, and proliferation. These results indicated that optimized Au–HAp–Col nanoparticles may be promising drug delivery and scaffold materials for multifunctional biomedical applications.