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1.
Gold nanoparticles with size 3-10nm (diameter) were prepared by the reduction of HAuCl4 in a CTAB/octane 1-butanol/H2O reverse micelle system using NaBH4 as the reducing agent.The as-formed gold nanoparticle colloid was characterized by UV/vis absorption spectrum and transmission electron microscopy(TEM).Various capping ligands,such as alkylthiols with different chain length and shape,trioctylphosphine(TOP),and pyridine are used to passivate the gold nanoparticles for the purpose of self-organization into superstructures.It is shown that the ligands have a great influence on the selforganization of gold nanoparticles into superlattices,and dodecanethiol C12H25SH is confirmed to be the best ligand for the self-organization.Self-organization of C12H25SH-capped gold nanoparticles into 1D,2D and 3D supperlattices has been observed on the carbon-coated copper grid by TEM without using any selective precipitation process. 相似文献
2.
Due to their small size (1-100 nm), nanoparticles exhibit novel materials properties that differ considerably from those of the bulk solid state. Especially in recent years, the interests in nanometer-scale magnetic particles are growing based on their potential application as high density magnetic storage media. A unique reverse micelle method has been developed to prepare gold-coated iron nanoparticles. XRD, UV/vis, TEM and magnetic measurements are used to characterize the nanocomposites. XRD only gives FCC paterns of gold for the obtained nanoparticles. There is a red shift and broadening of Au@Fe colloid relative to pure gold colloid in the absorption spectra. TEM results show that the average size of Au@Fe nanoparticle is about 10 nm. These nanoparticles self-assembled into wires in micron level under a 0.5 T magnetic field. Magnetic measurements show that the particles are superparamagnetic with a blocking temperature of 42 K. Coercivity of the obtained nanoparticles decreases with the measuring temperature, which are 730 Oe,320 Oe and 0 at 2 K, 10 K and 300 K, respectively. 相似文献
3.
Ryoji Inaba Takayuki Fukahori Masato Hamamoto Teruhisa Ohno 《Journal of molecular catalysis. A, Chemical》2006,260(1-2):247-254
Nanosized pure TiO2 particles with high crystallinity and large surface area were prepared by hydrolysis of tetrabutyl titanate in water/Triton X-100/isooctane reverse micelle solutions as reaction media followed by hydrothermal treatment to improve crystallinity. The prepared TiO2 nanoparticles were characterized by XRD, BET, TGA, FT-IR and TEM. The size of ultrafine particles was controlled by changing the water content of the reverse micelle solution. The TiO2 particles showed monodispersity, large surface area and high degrees of crystallinity and thermostability. The photocatalytic activity of the TiO2 particles was evaluated by decomposition of toluene in the gas phase. The activity of the TiO2 nanoparticles was higher than that of commercially available anatase fine particles, such as ST-01, which is one of the most active photocatalysts for degradation of organic compounds in the gas phase. 相似文献
4.
Yao Wang Guanwei Wei Fei Wen Xu Zhang Wangqing Zhang Linqi Shi 《Journal of molecular catalysis. A, Chemical》2008,280(1-2):1-6
The copolymer of poly(N-isopropylacrylamide)-co-poly(4-vinylpyridine) was synthesized by free radical copolymerization of 4-vinylpyridine and N-isopropylacrylamide. The copolymer synthesized with the feed monomer ratio of 4-vinylpyridine/N-isopropylacrylamide equal to 1/3 was associated to form thermoresponsive colloid in neutral water at room temperature, the average size and the cloud-point temperature of which were 40 nm and 32 °C, respectively. The thermoresponsive colloid was used as scaffold to load 2-nm Au nanoparticles to form the responsive catalyst of colloid-stabilizing gold nanoparticles. The catalysis in the model reduction of 4-nitrophenol with NaBH4 suggested that the catalytic reduction could be modulated due to the thermoresponsive phase-transition of the colloid-stabilizing gold nanoparticles. That was, the catalytic reduction firstly accelerated with the increase in temperature below the cloud-point temperature and then decelerated with the increase in temperature above the cloud-point temperature of the thermoresponsive colloid-stabilizing Au nanoparticles. 相似文献
5.
Mono- and di-alkylated polyethylenimines (PEI-1R, PEI-2R) were synthesized and used as both reductants, by exploiting the functionality of the polyethylenimine's (PEI) amino groups, and stabilizers able to protect nascent gold nanoparticles generated from hydrogen tetrachloroaurate (HAuCl4). From TEM images of the stained polymers, it is clear that the polymer micelles are round and well-structured when formed from PEI-2R, fused and less well-structured when formed from PEI-1R, and totally nonstructured when formed from PEI. These findings coincide with the results found by using pyrene as a probe to investigate aggregation behavior, where PEI-2R with a fluorescence intensity ratio (I1/I3) of 1.48 forms the more closely packed polymer micelles than PEI-1R (I1/I3 = 1.64) and PEI (I1/I3 = 1.72). The use of the highly alkylated polymer micelle (PEI-2R) results in the fastest reduction of HAuCl4, and gives the most effective protection to the generated gold nanoparticles. When used at higher polymer concentrations than required for micelle formation, it was found that polymer hydrophobicity was highly influential in directing the nanoparticle's morphology, i.e., the resulting polymer micelles were labeled with perfect and round necklace-like gold nanoparticles when PEI-2R was used, and imperfect and less round gold nanoparticles when PEI-1R was employed. These structures were totally absent when PEI was used. The use of alkylated PEI, being able to act simultaneously as both a reductant and as a very effective protective agent, greatly simplifies the process used for preparing gold nanoparticles. 相似文献
6.
Preparation of Functionalized Fe3O4@SiO2 Magnetic Nanoparticles for Monoclonal Antibody Purification
HOU Xuemei ZHAO Changjie TIAN Yanlong DOU Shuliang ZHANG Xiang ZHAO Jiupeng 《高等学校化学研究》2016,32(6):889-894
Magnetic Fe3O4@SiO2 nanoparticles with superparamagnetic properties were prepared via a reverse mi-croemulsion method at room temperature. The as-prepared samples were characterized by transmission electron mi-croscopy(TEM), X-ray diffractometry(XRD), and vibrating sample magnetometry(VSM). The Fe3O4@SiO2 nanoparticles were modified by (3-aminopropyl)triethoxysilane(APTES) and subsequently activated by glutaraldehyde(Glu). Protein A was successfully immobilized covalently onto the Glu activated Fe3O4@SiO2 nanoparticles. The adsorption capacity of the nanoparticles was determined on an ultraviolet spectrophotometer(UV) and approximately up to 203 mg/g of protein A could be uniformly immobilized onto the modified Fe3O4@SiO2 magnetic beads. The core-shell of the Fe3O4@SiO2 magnetic beads decorated with protein A showed a good binding capacity for the chime-ric anti-EGFR monoclonal antibody(anti-EGFR mAb). The purity of the anti-EGFR mAb was analyzed by virtue of HPLC. The protein A immobilized affinity beads provided a purity of about 95.4%. 相似文献
7.
O. Margeat F. Dumestre C. Amiens B. Chaudret P. Lecante M. Respaud 《Progress in Solid State Chemistry》2005,33(2-4):71-79
Hydrogenation of bis(ditrimethylsilyl)amido iron complex, [Fe{N(SiMe3)2}2], provides iron nanoparticles (NPs) which have been stabilised either by an organic polymer matrix or mixtures of long chain acid and amine ligands leading respectively to spherical nanoparticles of 1.8 nm size or nanocubes with edges of 7.2 or 8.4 nm. The 1.8 nm size NPs are magnetically independent. Their magnetisation is shown to be identical to that of clusters of the same size prepared and measured in UHV conditions, i.e. strongly increased as compared to bulk value. These NPs have been structurally characterised and display an original structure different from the classical bcc and fcc structures encountered in bulk iron. On the reverse iron nanocubes display a bcc structure and magnetic properties similar to those of bulk iron within experimental errors, in agreement with their larger size. These cubes crystallise into 3D superstructures. 相似文献
8.
A facile approach was developed to prepare highly dispersed TiO2 nanoparticles with selected phase. The crystallization phase of the nanoparticles can be easily tuned from anatase to rutile by the dosage of hydrochloric acid in the reaction system. The crystallite size of the as-prepared anatase TiO2 nanoparticles was ca. 3.2 nm with high dispersion. A transparent TiO2 colloid was obtained by dispersing the as-prepared anatase TiO2 nanoparticles in deionized water without any organic additives added. The concentration of TiO2-H2O colloid can be as high as 1600 g/L. The optical transmittance of TiO2-H2O colloid with a low concentration was nearly 100% in the visible region. Furthermore, anatase TiO2 nanoparticles(TiO2-NPs) showed superior photocatalytic performance compared to rutile TiO2-NPs. 相似文献
9.
Kanehira K Banzai T Ogino C Shimizu N Kubota Y Sonezaki S 《Colloids and surfaces. B, Biointerfaces》2008,64(1):10-15
Titanium dioxide (TiO2)/polyacrylic acid (PAA) (TiO2/PAA) particles were formed by mixing PAA and an acidic solution of TiO2 nanoparticles in dimethylformamide (DMF) followed by heat treatment. TEM and particle analysis showed that the resulting particles had a narrow size distribution. The colloid was very stable and aggregation was not observed over a wide pH range (3–9) or at high salt concentration. The residual carboxylic acid of PAA could be modified via EDC/NHS activation to form an amide bond with a protein. An antibody was attached to the hybrid nanoparticle and specific binding to antigen was monitored by surface plasmon resonance. The results suggest that TiO2/PAA nanoparticles are candidates as the base component of a photocatalytic system with potential for substrate selectivity. 相似文献
10.
介绍一个仪器分析综合实验——纳米Fe_2O_3和Fe_3O_4的制备及其催化高氯酸铵热分解性能的研究。采用水热法合成纳米Fe_3O_4,进而煅烧得到纳米Fe_2O_3。使用X射线粉末衍射(XRD)对制得的样品结构进行表征,通过透射电镜(TEM)可以发现其为球形颗粒,粒径在10–20 nm范围内。将制得的纳米Fe_2O_3和纳米Fe_3O_4按不同比例加入高氯酸铵(AP)中,通过对混合物进行热分析(TG-DSC),发现纳米Fe_2O_3和纳米Fe_3O_4可以明显促进AP的分解,且Fe_2O_3的催化效果优于Fe_3O_4的催化效果,并对催化机理进行了简单讨论。通过该实验,可以让学生学习水热反应的方法,掌握利用XRD、热分析等多种手段对化合物结构及性能进行表征的技能。 相似文献
11.
Lei Qian Xiurong Yang 《Colloids and surfaces. A, Physicochemical and engineering aspects》2005,260(1-3):79-85
Ag(Au) bimetallic core–shell nanoparticles were prepared by a new seed growth method. Ascorbic acid was used to reduce the complex of HAuCl4 and hexadecyltrimethylammoniumbromide (CTAB). This resulted in the forming of colorless Au(I) (AuCl2−). It was used as the growth solution to prepare these bimetallic core–shell nanoparticles. These nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed these nanoparticles exhibited core–shell shape and there was large amount of Ag in the shell. These nanoparticles could be produced in a few minutes without violent stirring and the method was easy and convenient compared with others. The effect of amount of AuCl2− on the shape of nanoparticles was also studied. Many small gold nanoparticles were formed on the surface of bimetallic core–shell nanoparticles in the presence of excess AuCl2−. The mechanisms were also proposed to explain the process of colloidal preparation. 相似文献
12.
Peptide Conjugates for Directing the Morphology and Assembly of 1D Nanoparticle Superstructures
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Chen Zhang Dr. Chengyi Song Dr. H. Christopher Fry Prof. Nathaniel L. Rosi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):941-945
Designed peptide conjugates molecules are used to direct the synthesis and assembly of gold nanoparticles into complex 1D nanoparticle superstructures with various morphologies. Four peptide conjugates, each based on the gold‐binding peptide (AYSSGAPPMPPF; PEPAu), are prepared: C12H23O‐AYSSGAPPMPP ( 1 ), C12H23O‐AYSSGAPPMPPF ( 2 ), C12H23O‐AYSSGAPPMPPFF ( 3 ), and C12H23O‐AYSSGAPPMPPFFF ( 4 ). The affect that C‐terminal hydrophobic F residues have on both the soft‐assembly of the peptide conjugates and the resulting assembly of gold nanoparticle superstructures is examined. It is shown that the addition of two C‐terminal F residues ( 3 ) leads to thick, branched 1D gold nanoparticle superstructures, whereas the addition of three C‐terminal F residues ( 4 ) leads to bundling of thin 1D nanoparticle superstructures. 相似文献
13.
Sn(OH)4 was prepared by the conventional solution precipitate method, followed by supercritical CO2 drying. The resultant Sn(OH)4 was divided into three aliquots and calcined at 400, 600 and 800℃, respectively, thus SnO2 nanoparticles with average crystallite sizes of 5, 10 and 25 nm were obtained. Furthermore, three SnO2 thick film gas sensors(denoted as sensors S-400, S-600 and S-800) were fabricated from the above SnO2 nanoparticles. The adhesion of sensing materials on the surface of alumina tube is good. Compared to the sensors S-600 and S-800, sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol. On the other hand, sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600. X-Ray diffraction(XRD), transmission electron microscopy(TEM) and selective area electron diffraction(SAED) measurements were used to characterize the SnO2 nanoparticles calcined at different temperatures. The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy(SEM). 相似文献
14.
XU Shi-hong TAN Dong-dong BI De-fu SHI Peng-hui LU Wei SHANGGUAN Wen-feng MA Chun-yan 《高等学校化学研究》2013,29(1):121-125
A series of magnetically separable photocatalyst TiO2/NiFe2O4(TN) with different mass ratios of NiFe2O4 to TiO2 was prepared by sol-gel method. The X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM), ultraviolet-visible spectroscopy(UV-Vis), Brunauer-Emmett-Teller(BET) surface analysis and photoluminescence spectroscopy(PL) were used to characterize the photocatalyst TN. The XRD patterns of TN indicate that adulterating a smidgen of NiFe2O4 into TiO2(about 0.1%, mass ratio) can promote the phase transformation of TiO2, however, when the doped amount of NiFe2O4 surpasses 1%, the introduction of NiFe2O4 can inhibit the growth of TiO2 crystal grain and reduce the size of TiO2 crystal grain. The XPS results of TN indicate that some Fe3+ replace Ti4+ of the TiO2 lattice forming Fe―O―Ti bonds. The PL analysis of TN shows that the NiFe2O4 nanoparticles in photocatalyst TN play the role of the effective recombination centre of the photogenerated electrons and holes, leading to the decrease in photocatalytic activity. 相似文献
15.
Donghong Yin Liangsheng Qin Jianfu Liu Chengyong Li Yong Jin 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):40-48
Three kinds of mesoporous alumina (denoted as meso-Al2O3-x (x = a, b, c)) supports with different surface basicity were synthesized by different structure-direct agent and different assembly pathway, respectively. The surface basicity of the meso-Al2O3-x and the commercial γ-Al2O3 was measured by means of CO2-TPD and IR spectroscopy. The profiles of CO2-TPD and IR spectra indicated that the mesoporous alumina owned more abundant surface basic sites than that of γ-Al2O3. Au nanoparticles deposited on the above supports via the method of homogeneous deposition precipitation (HDP) using urea as the precipitation agent. The supported Au catalysts were characterized by N2 adsorption–desorption isotherms, TEM, XPS and testing the catalytic performances in the epoxidation of styrene. The dispersion and average size of the gold particles are dependent of the number of surface basic sites on the supports. Transmission electron microscopy (TEM) observations show a homogeneous distribution of gold particles lower than 4 nm on meso-Al2O3-b and meso-Al2O3-c, which owned more basic sites on the surface. XPS spectra reveal that only metallic state of Au is presented on the supports, which is independent of surface properties. The different Al2O3 supported Au catalysts were employed as highly active/selective and reusable catalysts for the epoxidation of styrene by anhydrous t-butyl hydroperoxide (TBHP). Au nanoparticles as well as the surface basic sites of the support are responsible for the epoxidation. 相似文献
16.
以K2PdCl4/K2Ni(CN)4为前驱体制备了具有凝胶特性的氰胶(Cyanogels), 利用硼氢化钠还原氰胶得到三维多孔珊瑚状PdNi合金前驱体, 在此基础上通过原位Galvanic置换反应, 制备得到内核为PdNi合金、 表面具有不同厚度Au层的三维多孔PdNi@Au催化剂. X射线衍射(XRD)分析和透射电子显微镜(TEM)观测结果显示, 该三维网状结构由粒径约7 nm的纳米颗粒相互连接形成; 能量分散光谱(EDX)线性扫描和元素分布(Mapping)分析显示该催化剂具有典型的核壳结构. 电化学测试结果表明, 表面Au层的厚度影响PdNi@Au催化剂的性能, 当Au的含量(摩尔分数)为5.6%时, 催化剂显示出对甲酸最佳的电催化活性, 对甲酸电催化氧化的峰电流密度达到商业化铂黑催化剂的7.2倍. 相似文献
17.
Lijin Xie Junfeng Ma Zhongqiang Zhao Hua Tian Jun Zhou Yonggang Wang Jiantao Tao Xiaoyi Zhu 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):232-236
Nanometer-sized Bi4Ti3O12 particles have been prepared by chemical reaction of bismuth nitrate pentahydrate, titanium sulfate and ammonia solution in a reverse microemulsion system consisting of water, OP (P-octyl polyethylene glycol phenylether, non-ionic surfactant), n-butanol (co-surfactant), and cyclohexane (oil). Precursor hydroxides precipitated in the droplets of water-in-oil (w/o) microemulsion were calcined at 800 °C for 4 h to form Bi4Ti3O12 nanoparticles. The samples were investigated with X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectrophotometer (FT-IR) and ultraviolet visible spectrophotometer (UV–vis). It was found that the as-prepared Bi4Ti3O12 nanoparticles had small particle sizes (35 nm), high crystallinity, narrow size distributions and strong light absorption properties not only in the ultraviolet light but also in the visible light region. 相似文献
18.
We synthesized 5.5 nm Au nanocrystals coated by dodecanethiol (C12SH26) by reverse micelle method. The Au nanocrystals are multiply twinned particles (MTP), which are mainly characterized by decahedral and icosahedral structures. The 2D hexagonal network self-organizationa of Au nanocrystals are realized on both amorphous carbon (AC) and highly oriented pyrolitic graphite (HOPG) surfaces. The stability of 2D superlattices of Au nanocrystals in vacuum has been systematically surveyed, and it is found that large single triangular nanocrystals have been formed after 75 days due to the coalescence among the neighboring nanoparticles and the rearrangement of the atomics. When the Au nanocrystals in 2D organizations are annealed in air (573 K, 15 min), higher ordered 2D self-assemblies are stable, whereas worm-like coalesced nanoparticles form in those less ordered organizations. This demonstrates that the thermal stability of 2D self-assemblies is determined by the level of nanocrystals ordering. 相似文献
19.
Terbium orthophosphate nanoparticles were synthesized using 1-hydroxy ethylidene-1,1-diphosphonic acid(HEDP) as a capping ligand under hydrothermal conditions at 80℃. These HEDP-capped TbPO4 nanoparticles owned a hexagonal phase structure according to the powder X-ray diffraction(XRD) results and were spherical monodispersed particles with a diameter of about 10 nm confirmed by transimission electron microscope(TEM) images. Interestingly, the luminescent intensities of the HEDP-capped TbPO4 nanoparticles decreased obviously in the presence of Pb2+ ions and such a quenching behavior of luminescence was well fitted by the Stern-Volmer equation. 相似文献
20.
Customizing core-shell nanostructures is considered to be an efficient approach to improve the catalytic activity of metal nanoparticles. Various physiochemical and green methods have been developed for the synthesis of core-shell structures. In this study, a novel liquid-phase hydrogen reduction method was employed to form core-shell Pt@Au nanoparticles with intimate contact between the Pt and Au particles, without the use of any protective or structure-directing agents. The Pt@Au core-shell nanoparticles were prepared by depositing Au metal onto the Pt core; AuCl4− was reduced to Au(0) by H2 in the presence of Pt nanoparticles. The obtained Pt@Au core-shell structured nanoparticles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution TEM, fast Fourier transform, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and H2-temperature programmed reduction (H2-TPR) analyses. The EDX mapping results for the nanoparticles, as obtained from their scanning transmission electron microscopy images in the high-angle annular dark-field mode, revealed a Pt core with Au particles grown on its surface. Fourier transform measurements were carried out on the high-resolution structure to characterize the Pt@Au nanoparticles. The lattice plane at the center of the nanoparticles corresponded to Pt, while the edge of the particles corresponded to Au. With an increase in the Au content, the intensity of the peak corresponding to Pt in the FTIR spectrum decreased slowly, indicating that the Pt nanoparticles were surrounded by Au nanoparticles, and thus confirming the core-shell structure of the nanoparticles. The XRD results showed that the peak corresponding to Pt shifted gradually toward the Au peak with an increase in the Au content, indicating that the Au particles grew on the Pt seeds; this trend was consistent with the FTIR results. Hence, it can be stated that the Pt@Au core-shell structure was successfully prepared using the liquid-phase hydrogen reduction method. The catalytic activity of the nanoparticles for the oxidation of toluene was evaluated using a fixed-bed reactor under atmospheric pressure. The XPS and H2-TPR results showed that the Pt1@Au1/Al2O3 catalyst had the best toluene oxidation activity owing to its lowest reduction temperature, lowest Au 4d & 4f and Pt 4d & 4f binding energies, and highest Au0/Auδ+ and Pt0/Pt2+ proportions. The Pt1@Au2Al2O3 catalyst showed high stability under dry and humid conditions. The good catalytic performance and high selectivity of Pt@Au/Al2O3 for toluene oxidation could be attributed to the high concentration of adsorbed oxygen species, good low-temperature reducibility, and strong interaction. 相似文献