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A new approach was developed to control the size of gold nanoparticles in citrate reduction by altering the concentration of chloride ions. The size of the as-prepared gold nanoparticles could be tuned in the range 19-47 nm at a specific molar ratio of citrate and tetrachloroauric acid (5:1) by simply changing the concentration of chloride ions from 0 to 20 mM. UV-visible spectra and TEM observations showed that the increased size of the gold particles was primarily related to the promoted aggregation of the primary gold particles. The aggregation was attributed to their decreased surface charge as the chloride ion concentration in the reaction solutions increased. This approach could also be extended to other reaction systems, for example, the size of gold nanoparticles prepared by NaBH(4) reduction increased from 3 to 12 nm as the chloride ion concentration was increased from 0 to 20 mM. 相似文献
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Teen-Hang Meen Jenn-Kai Tsai Shi-Mian Chao Yu-Chien Lin Tien-Chuan Wu Tang-Yun Chang Liang-Wen Ji Walter Water Wen-Ray Chen I-Tseng Tang Chien-Jung Huang 《Nanoscale research letters》2013,8(1):450
In this study, we prepared different shapes of gold nanoparticles by seed-mediated growth method and applied them on the photoelectrodes of dye-sensitized solar cells (DSSCs) to study the surface plasma resonant (SPR) effect of gold nanoparticles on the photoelectrodes of dye-sensitized solar cells. The analyses of field emission scanning electron microscopy show that the average diameter of the spherical gold nanoparticles is 45 nm, the average length and width of the short gold nanorods were 55 and 22 nm, respectively, and the average length and width of the long gold nanorods were 55 and 14 nm, respectively. The aspect ratio of the short and long gold nanorods was about 2.5 and 4, respectively. The results of ultraviolet–visible absorption spectra show that the absorption wavelength is about 540 nm for spherical gold nanoparticles, and the absorption of the gold nanorods reveals two peaks. One is about 510 to 520 nm, and the other is about 670 and 710 nm for the short and long gold nanorods, respectively. The best conversion efficiency of the dye-sensitized solar cells with spherical gold nanoparticles and short and long gold nanorods added in is 6.77%, 7.08%, and 7.29%, respectively, and is higher than that of the cells without gold nanoparticles, which is 6.21%. This result indicates that the effect of gold nanoparticles on the photoelectrodes can increase the conductivity and reduce the recombination of charges in the photoelectrodes, resulting in the increase of conversion efficiency for DSSCs. In addition, the long gold nanorods have stronger SPR effect than the spherical gold nanoparticles and short gold nanorods at long wavelength. This may be the reason for the higher conversion efficiency of DSSCs with long gold nanorods than those of the cells with spherical gold nanoparticles and short gold nanorods. 相似文献
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The knowledge of the cellular molar concentration of a drug is an extremely important parameter for the discussion and interpretation of its efficacy and bioavailability. Concerning metal complexes, electrothermal atomic absorption spectroscopy (ETAAS) offers a valuable analytical tool. However, matrix effects often hamper proper quantification of the metal concentration in biological tissues. This paper describes the development of an ETAAS method for the quantification of the molar gold concentration in HT-29 colon carcinoma cells. ETAAS analytical conditions were optimised and a factor was developed which allows the calculation of the molar cellular gold concentration from the measured gold per cellular biomass value. The method was used to quantify the gold content in HT-29 cells after exposure to the gold drug auranofin. Results indicated a strong cellular uptake of auranofin (compared to other metal anticancer drugs), which significantly correlated with the antiproliferative effects triggered by this agent. 相似文献
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新型水溶性含巯基纤维素衍生物的合成及表征 总被引:7,自引:0,他引:7
用CMC与巯基乙酸在一定条件下制得一种新型的在强碱性条件下可溶解的纤维素衍生物(CMCSH).CMCSH具有较好的储存稳定性,在室温下避光保存半年,巯基含量及对金的回收率不变.在助凝剂CaCl2存在下,对金具有较好的絮凝回收作用,发现决定絮凝回收效率的主要因素是巯基与金的摩尔比值,当该比值大(9:1)时,在一分钟内对金回收率可达97%以上.常见的四种杂离子Cu2+、Zn2+、Fe3+和Pb2+在一定浓度范围内对本法絮凝回收金无不良影响. 相似文献
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Compounds containing gold are still an important means of decoration of porcelain, faience, and glass products. The attempts to replace gold with other metals, such as organic iron compounds did not bring the expected results. The film imitating gold is not durable enough and has less decorative properties than gold does. 相似文献
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探讨了用非氰化法从混合型金矿中浸取金的可能性,主要研究了硫脲法浸金时,硫酸铁浓度,硫脲浓度,酸度,温度,浸取时间及固液化等实验条件对金浸出率的影响,并与微波等方法进行了比较。 相似文献
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Weiling Deng Colin Carpenter Nan Yi Maria Flytzani-Stephanopoulos 《Topics in Catalysis》2007,44(1-2):199-208
We compare the activity and relevant gold species of nanostructured gold–cerium oxide and gold–iron oxide catalysts for the
CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO
oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze
the water-gas shift reaction. Gold species weakly bound to ceria (doped with lanthana) or iron oxide can be removed by sodium
cyanide at pH ≥12. Both parent and leached catalysts were investigated. The activity of the leached gold–iron oxide catalyst
in CO oxidation is approximately two orders of magnitude lower than that of the parent material. However, after exposure to
H2 up to 400 °C gold diffuses out and is in reduced form on the surface, a process accompanied by a dramatic enhancement of
the CO oxidation activity. Similar results were found with the gold–ceria catalysts. On the other hand, pre-reduction of the
calcined leached catalyst samples did not promote their water-gas shift activity. UV–Vis, XANES and XPS were used to probe
the oxidation state of the catalysts after various treatments. 相似文献
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介绍了无氰仿金镀层的种类,综述了国内外无氰仿金电镀的研究现状,包括焦磷酸盐体系、酒石酸盐体系、HEDP体系以及其他一些配位剂体系.最后对无氰仿金电镀的发展趋势进行了展望. 相似文献
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Multi-walled carbon nanotube (MWCNT)/thionine/gold nanoparticle composites were prepared by binding gold nanoparticles to the surfaces of thionine-coated carbon nanotubes. TEM images show gold nanoparticles distributed uniformly on nanotube walls and ends. UV-Vis, Raman, FT-IR, and zeta potential measurements were used to examine the properties of the resulting products. The composites demonstrate significant electrocatalytic activity for oxygen reduction. Although only gold nanoparticles were investigated here, the method could be easily extended to attach other metallic nanoparticles to the sidewalls of carbon nanotubes. 相似文献
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M. A. Centeno M. C. Hidalgo M. I. Dominguez J. A. Navío J. A. Odriozola 《Catalysis Letters》2008,123(3-4):198-206
A series of Au/TiO2 samples with gold loadings ranging from 0.11% to 1.26% have been prepared by deposition–precipitation, characterised by means of XRD, SBET, XRF, TEM, XPS and DR UV–Vis techniques and tested in the gaseous CO oxidation and photocatalytic degradation of phenol in aqueous media. The catalytic performances of the solids on both reactions depend on the gold content. Besides this, the gold particle size plays a determinant role in the catalytic activity for the CO reaction, but apparently its influence on the photocatalytic activity appears to be negligible and only very small gold particles seem to participate on the photocatalytic process. On the other hand, the electronic properties of the solids, measured by its band gap energy, are a key factor in the photochemical activity but do not have a clear influence in the CO oxidation reaction. 相似文献
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The one- and two-photon excitation emission properties of water soluble glutathione monolayer protected gold clusters were investigated. Strong two-photon emission was observed from the gold clusters. The two-photon absorption cross section of these gold clusters in water was deduced from the z-scan measurement to be 189?740 GM, which is much higher compared to organic fluorescent dyes and quantum dots. These gold clusters also showed high photo-stability. The MTT assay showed that these gold clusters have low toxicity even at high concentrations. We have successfully demonstrated their applications for both one and two-photon excitation live cell imaging. The exceptional properties of these gold clusters make them a promising alternative for one- and two-photon bio-imaging and other nonlinear optical applications. 相似文献
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Yukiko Takahashi Waki Yukita Maya Chatterjee Toshishige M. Suzuki 《Reactive and Functional Polymers》2008,68(10):1476-1482
An amphiphilic copolymer composed of maleic acid and alkyl (C18) vinyl monomer was encapsulated into the porous support. A series of colloidal gold nanoparticles of known size was substantially immobilized in the composite porous supports based on cross-linked polyacrylate ester and cross-linked polystyrene resin. Maleic acid moiety of the amphiphilic copolymer can act as a stabilizer for gold nanoparticles in analogy to citric acid, whereas alkyl chains play a role for the stable accommodation of the amphiphilic copolymer. Maleic acid stabilizes the gold nanoparticles by flexing the geometrical arrangement of the linear polymer. Presence of C18 alkyl chain in the poly(C18-vinyl maleate) is indispensable to act as spacing group that prevents mutual aggregation of gold nanoparticles. On the other hand, gold nanoparticles with average diameter of less than 8 nm were spontaneously formed by treatment of the composite resin beads with aqueous HAuCl4 solution, subsequently dispersed inside the pores of resin beads as observed by TEM. We have also elucidated the catalytic activity of the material with the hydrogenation of cinnamaldehyde in supercritical carbon dioxide. Notably, apparent size effect of gold was observed in the selectivity of the reaction. 相似文献
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A. Warshawsky N. Kahana V. Kampel I. Rogachev R. M. Kautzmann J. L. Cortina C. H. Sampaio 《大分子材料与工程》2001,286(5):285-295
Ion exchange technology is offered as an alternative to activated carbon for gold cyanide recovery. A new type of ion‐exchange resin (PS‐PIP) incorporating a piperazine group, linked to a styrene‐divinylbenzene macroporous network, is described. The extraction of Au(CN)2– and other metal cyanides with the PS‐PIP resin involves three modes of metal extraction: the protonated secondary amine groups of the resin (at acidic pH conditions), the free amine groups of the resin (at neutral and basic pH values) and the small portion of the quaternary ammonium groups participate in the gold extraction mechanism. The gold cyanide extraction reaction on the polymeric piperazine was studied by a combination of metal extraction data, from batch experiments, and IR and XPS spectroscopic analysis of the metal loaded polymers. Extraction isotherms of gold cyanide show that gold binding is possible from 40–60 mg Au/g of resin in alkaline solutions, up to 150 mg Au/g of resin in acidic solutions. Efficient stripping of gold from the resin was achieved using ethanol/water solutions of sodium hydroxide, or 0.5 mol/l thiourea in sulfuric acid solutions. 相似文献
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This paper is a brief review of suggested structures of catalytic sites and reaction mechanisms in CO oxidation catalyzed by highly dispersed supported gold. The review is focused on evidence of the sites, which has been determined primarily by infrared, X-ray absorption, and other spectroscopies, often combined with transmission electron microscopy; theory has also been applied to characterize supported gold catalysts. The literature gives strong evidence of the reaction of oxygen with CO adsorbed on zerovalent gold at low temperature, consistent with the role of such adsorbed CO in the catalytic reaction. There is also strong evidence of the involvement of cationic gold, even isolated single sites, in the catalysis at higher temperatures (e.g., room temperature). Because CO is only weakly adsorbed on zerovalent gold and more strongly adsorbed on cationic gold, it is suggested that the cationic gold sites may be kinetically more significant than the zerovalent gold sites under potentially practical reaction conditions. 相似文献