首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
电连接器镀金工艺   总被引:2,自引:0,他引:2  
池建明  王丽娟 《电镀与涂饰》2002,21(5):34-36,50
金镀层具有优良的各项性能,采用合金化镀金可进一步提高镀金层的硬度和耐磨性。本文介绍了镀金工艺的分类,比较了几种常用镀金工艺如金钴、金镍和金铁合金的特点及应用。  相似文献   

2.
金是一种高化学惰性金属,其纳米粒子具有独特的结构和性质,在催化、光电传感器和生物医药等领域应用广泛。研究表明,负载在金属氧化物等载体上的纳米金粒子具有很高的催化活性,特别是在CO低温催化氧化中,催化效率明显高于其他类型贵金属。纳米金催化剂的研究已经具有了相当的深度和广度,在工业催化和环境保护等领域显现出重要的发展前景和商机。  相似文献   

3.
L Zhao  D Jiang  Y Cai  X Ji  R Xie  W Yang 《Nanoscale》2012,4(16):5071-5076
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   

4.
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   

5.
Ott I  Scheffler H  Gust R 《ChemMedChem》2007,2(5):702-707
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   

6.
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   

7.
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   

8.
杨春芬  杨中民 《云南化工》1995,(4):11-13,10
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   

9.
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   

10.
尚军刚  杨要锋  赵可江 《化学世界》2011,52(11):696-698
介绍了当前国内外难选冶矿黄金冶炼工艺、技术和实验研究,对包括目前较为成熟的沸腾 焙烧、两段焙烧、生物预氧化、热压氧化、化学氧化等金精矿预处理工艺进行了比较,并对氰化法工艺、金精炼工艺和其它金浸出药剂工艺的研究分别进行了论述.最后对难选冶矿金回收研究应用的前景和方向进行展望.  相似文献   

11.
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   

12.
王明星  何婧琳  曹忠 《广东化工》2011,(8):60-61,77
金纳米材料具有特殊的物理、化学性质。与其他形状的金纳米材料相比,金纳米棒同时具有化学和光学方面的备向异性,在材料科学、局域表面等离子体共振(LSPR)传感、生物医学等领域存在着巨大的应用前景。文章系统的评述了金纳米棒的合成及应用进展。具体内容包括金纳米棒的合成、金纳米棒的光学特性、金纳米棒在LSPR传感分析方面的应用以及金纳米棒在生物医学方面的应用。  相似文献   

13.
低品位铁锰型金银矿由于金银被铁锰等矿物包裹,传统浸金银的方法无法达到目的。采用两矿加酸法对矿预先浸锰,破坏原矿物结构,降低体系的氧化还原电位,然后用硫脲同时浸出金银,可达理想浸出效果。考察了硫脲用量、硫酸钠用量及氧化还原电位等对金银浸出率的影响,优惠条件下金银的浸出率分别达到98.0%和45.0%。同时用电化学和配位化学的理论对硫脲浸出金银的过程进行了描述。  相似文献   

14.
Zhijuan Wang  Meiye Li  Junhua Yuan  Li Niu  Ari Ivaska 《Carbon》2007,45(10):2111-2115
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   

15.
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   

16.
近十年,随着手机用户的增加,产生了大量的废旧手机。机芯是手机的核心部件,不仅数量大,而且含有大量可回收的Cu、Au、Ag、Pd等金属,值得加以回收。作者运用电化学方法回收Cu后,采用湿法冶金提取阳极泥中的Au、Ag、Pd,回收率较高,对环境污染较少。  相似文献   

17.
Polavarapu L  Manna M  Xu QH 《Nanoscale》2011,3(2):429-434
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   

18.
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   

19.
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   

20.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号