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Reactions of gold anions and cations generated by laser desorption/ionization were studied in the FTICR spectrometer. Au− associated with C6F6 to give the novel Au−(C6F6) complex, whose binding energy was estimated to be 24 ± 4 kcal mol−1 from analysis of the radiative association (RA) kinetics. Au+ associated with C6F5H to give Au+(C6F5H), with binding energy estimated to be 31 kcal mol−1. Au+ reacted with C6H6 to form the well known Au+(C6H6) and Au+(C6H6)2 complexes. The observation of rapid charge transfer from Au+(C6H6) to C6H6 was interpreted as showing that benzene binds more strongly to neutral Au than to Au+. The neutral Au–C6H6 bond is accordingly concluded to be stronger than about 70 kcal mol−1. 相似文献
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Au2、Au3小团族分子的结构和势能函数 总被引:2,自引:0,他引:2
原子团簇的结构和性质研究是当今物理学和材料学中的一个热门课题,过渡金属团簇特别是Au团簇,由于其独特的物理和化学性质而被广泛地应用于催化反应、材料吸附[1-2]和光的吸收中[3]。近年来,人们用不同的理论方法研究金原子团簇。H儯kkinen等人利用GGA方法研究了中性和阴离Au2-10团簇的性质[4];Bravo-P啨rez等人采用从头计算的HF和post-HF方法研究Au2-Au6小团簇[5],这些计算结果与实验值相比,相差较大。由于金团簇电子结构的复杂性,对Au体系考虑旋—轨耦合和电子相关效应是很重要的,这种计算的不确定性对Au的影响比IB簇的其它金属团… 相似文献
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采用密度泛函理论研究Au-Pd和Au-Pt 纳米团簇催化解离N2O. 首先根据计算得到Au19Pd和Au19Pt 团簇的最优构型(杂原子均位于团簇的表面). 以Au19Pd催化解离N2O为例研究催化解离的反应机理. 对此主要考虑两个反应机理, 分别是Eley-Rideal (ER)和Langmuir-Hinshelwood (LH). 第一个机理中N2O解离的能垒是1.118 eV, 并且放热0.371 eV. N2分子脱附后, 表面剩余的氧原子沿着ER路径消除需要克服的能垒是1.920eV, 这比反应沿着LH路径的能垒高0.251 eV. 此外根据LH机理, 氧原子在表面的吸附能是-3.203 eV, 而氧原子在表面转移所需的能垒是0.113 eV, 这表明氧原子十分容易在团簇表面转移, 从而促进氧气分子的生成. 因此, LH为最优反应路径. 为了比较Au19Pd和Au19Pt 对N2O解离的活性, 根据最优的反应路径来研究Au19Pt 催化解离N2O, 得到作为铂族元素的铂和钯对N2O的解离有催化活性, 尤其是钯. 同时, 将团簇与文献中的Au-Pd合金相比较, 得到这两种团簇对N2O 解离有较高的活性, 尤其是Au19Pd团簇. 再者, O2的脱附不再是影响反应的主要原因, 这可以进一步提高团簇解离N2O的活性. 相似文献
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Dichroic Nd3+:Au–antimony glass (K2O–B2O3–Sb2O3) nanocomposites (NCs) have been synthesized by single-step melt-quench thermochemical reduction process. The UV–Vis–NIR spectra show surface plasmon resonance (SPR) band of Au0 nanoparticles (NPs) and absorption peaks of Nd3+ ions. XRD and SAED results indicate growth of Au0 NPs along (200) plane. TEM image reveals elliptical Au0 NPs having sizes 12–21 nm (aspect ratio ~1.2) responsible for the dichroic behavior. Photoluminescent upconversion under excitation at 805 nm exhibit two emission bands of Nd3+ ions at 540 (green) and 650 (red) nm due to 4G7/2 → 4I9/2 and 4G7/2 → 4I13/2 transitions respectively. Both bands undergo maximum 8 and 11 fold intensity enhancements respectively at 0.03 wt% Au0 (4.1 × 1018 atoms/cm3). Local field enhancement (LFE) induced by Au0 SPR and energy transfer (ET) from Au0 → Nd3+ is found to be responsible for enhancement while ET from Nd3+ → Au0 and optical re-absorption due to Au0 SPR for quenching. 相似文献
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冠醚树脂对Au,Pt,Pd的吸附及微量Au的富集 总被引:1,自引:0,他引:1
本文叙述了冠醚树脂对Au、Pt、Pd配合物的吸附及金的分离富集。在王水介质中三种金属分别以HAuCl_4、H_2PtCl_6、H_2PdCl_6形式存在,离解时有H_3O~+离子和相应的阴离子生成。冠醚树脂吸附时,H_3O~+离子与冠醚环上的氧原子结合,而相应的AuCl_4、PtCl_6~(2-)、PdCl_6~(2-)则以对阴离子配位在外。实验结果表明,冠醚树脂的种类,王水浓度,配合物浓度,碱金属阳离子和卤素阴离子的存在均影响吸附。冠醚树脂对Au的吸附容量为19mg/g树脂以上,可用于Au的富集。 相似文献
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TiO2作为一种宽禁带(3.0~3.2 eV)半导体材料,由于具有优异的物理化学特性和独特的光电特性,在许多领域都展现出广泛的应用前景[1~3].材料的尺寸、结构和形貌能赋予材料一些特殊的性质,近年来人们致力于研究不同形貌的TiO2纳米材料,如TiO2纳米线和纳米管等[4],并将其应用在光催化[5]、太阳能电池[6]和锂离子电池[7]等领域,但关于其在紫外探测器上应用的报道很少[8~10].本文采用水热法在F∶SnO2(FTO)衬底上制备出纵向有序生长的金红石型TiO2纳米线阵列,通过光刻工艺和磁控溅射技术制备了背入射Au/TiO2/Au肖特基结紫外探测器,并测试了其光、暗电流,光响应度及量 相似文献
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液晶模板法制备Au纳米线 总被引:12,自引:0,他引:12
利用非离子表面活性剂C12E4的层状液晶作为模板,以氯金酸(HAuCl4)水溶液作为体系的水相和反应物,并利用C12E4中EO基团的还原性制备了Au的纳米线.研究表明,反应物的浓度、液晶体系的组成和反应时间都将影响产物的形貌.在适当条件下,可以得到直径约为20nm,长度达到几微米的均匀金纳米线,并探讨了纳米线形成过程中层状液晶的模板作用. 相似文献
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We perform in this work a comprehensive first-principles investigation on the geometric and electronic structures of Au(BO) 2 ? and Au(BS) 2 ? which are valent isoelectronic to the well-known Au(CN) 2 ? monoanion. Au(BO) 2 ? and Au(BS) 2 ? complexes prove to possess linear ground-state structures similar to Au(CN) 2 ? and the BO? and BS? ligands in them are found to be coordinated terminally via boron atoms to gold centers which are weakly negatively charged. Au–B bonds in Au(BO) 2 ? and Au(BS) 2 ? appear to have higher Wiberg bond indices (0.79 and 0.80) and more covalent components (60 and 53 %) than the corresponding values of Au–C interaction in Au(CN) 2 ? (0.67 and 39 %, respectively) at the same theoretical levels. Their Au–B bifurcation values of the electronic localization function also turn out to be higher than Au–C. These results strongly suggest that the Au–B bonds in Au(BO) 2 ? and Au(BS) 2 ? with multiple-bond character possess stronger covalent characters than Au–C in Au(CN) 2 ? . 相似文献
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Au/TiO2光催化分解臭氧 总被引:7,自引:0,他引:7
采用沉积-沉淀法制备了Au/TiO2催化剂,用透射电子显微镜、紫外-可见漫反射光谱和X射线光电子能谱进行了表征,结果表明,样品在空气中于200 ℃处理后,金以金属态Au0的形式沉积在TiO2表面. 与TiO2相比,担载金的TiO2具有明显的光催化分解O3的活性. 黑光灯光照20 h后, 1%Au/TiO2催化剂对O3的分解率仍达98%以上. TiO2上的Au簇作为电子的捕获中心,能够促使电子与空穴的有效分离. 而Au簇和载体TiO2的周界处作为O3新的吸附活性中心,促进了O3的分解. 相似文献
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Ting Li Brian Albee Matti Alemayehu Rocio Diaz Leigha Ingham Shawn Kamal Maritza Rodriguez Sandra Whaley Bishnoi 《Analytical and bioanalytical chemistry》2010,398(2):689-700
A comparative assessment of the 48-h acute toxicity of aqueous nanoparticles synthesized using the same methodology, including
Au, Ag, and Ag–Au bimetallic nanoparticles, was conducted to determine their ecological effect in freshwater environments
through the use of Daphnia magna, using their mortality as a toxicological endpoint. D. magna are one of the standard organisms used for ecotoxicity studies due to their sensitivity to chemical toxicants. Particle suspensions
used in toxicity testing were well-characterized through a combination of absorbance measurements, atomic force or electron
microscopy, flame atomic absorption spectrometry, and dynamic light scattering to determine composition, aggregation state,
and particle size. The toxicity of all nanoparticles tested was found to be dose and composition dependent. The concentration
of Au nanoparticles that killed 50% of the test organisms (LC50) ranged from 65–75 mg/L. In addition, three different sized Ag nanoparticles (diameters = 36, 52, and 66 nm) were studied
to analyze the toxicological effects of particle size on D. magna; however, it was found that toxicity was not a function of size and ranged from 3–4 μg/L for all three sets of Ag nanoparticles
tested. This was possibly due to the large degree of aggregation when these nanoparticles were suspended in standard synthetic
freshwater. Moreover, the LC50 values for Ag–Au bimetallic nanoparticles were found to be between that of Ag and Au but much closer to that of Ag. The bimetallic
particles containing 80% Ag and 20% Au were found to have a significantly lower toxicity to Daphnia (LC50 of 15 μg/L) compared to Ag nanoparticles, while the toxicity of the nanoparticles containing 20% Ag and 80% Au was greater
than expected at 12 μg/L. The comparison results confirm that Ag nanoparticles were much more toxic than Au nanoparticles,
and that the introduction of gold into silver nanoparticles may lower their environmental impact by lowering the amount of
Ag which is bioavailable. 相似文献
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Dr. Peter M. Spurgeon Dr. Da-Jiang Liu Prof. Theresa L. Windus Prof. James W. Evans Prof. Patricia A. Thiel 《Chemphyschem》2021,22(4):349-358
Chemisorbed species can enhance the fluxional dynamics of nanostructured metal surfaces which has implications for applications such as catalysis. Scanning tunneling microscopy studies at room temperature reveal that the presence of adsorbed sulfur (S) greatly enhances the decay rate of 2D Au islands in the vicinity of extended step edges on Au(111). This enhancement is already significant at S coverages, θS, of a few hundredths of a monolayer (ML), and is most pronounced for 0.1–0.3 ML where the decay rate is increased by a factor of around 30. For θS close to saturation at about 0.6 ML, sulfur induces pitting and reconstruction of the entire surface, and Au islands are stabilized. Enhanced coarsening at lower θS is attributed to the formation and diffusion across terraces of Au−S complexes, particularly AuS2 and Au4S4, with some lesser contribution from Au3S4. This picture is supported by density functional theory analysis of complex formation energies and diffusion barriers. 相似文献
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《化学研究与应用》2015,(2)
本文通过一步水热法分别制备了Au、TiO2和Au/TiO2量子点。采用TEM和XRD测试手段对形貌、尺寸分布及组成进行了表征。结果表明,所得的Au、TiO2和Au/TiO2分别为近似球形,棒状和球形棒状交错的分散良好,没有团聚的纳米粒子,其尺寸峰值分别在3 nm、5 nm和4 nm左右,晶粒分布窄,为单分散量子点。Au量子点为面心立方结构,TiO2为典型锐钛矿结构,而Au/TiO2为兼有Au和TiO2两种结构。CO被催化为CO2的研究表明Au和Au/TiO2量子点对其均具有较高催化活性,且催化活性随着温度升高而增强。Au/TiO2复合物量子点的催化性能好于Au量子点,60℃便可以将CO完全氧化为CO2。TiO2和Au/TiO2量子点在甲基橙的降解反应中均具有较高的活性,在紫外光照射下均可在较短时间内将甲基橙完全降解,但负载型的Au/TiO2量子点降解效果更好。 相似文献
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Au纳米粒子在有机溶剂中的电导行为 总被引:1,自引:0,他引:1
采用化学方法制备出粒径约10nm的Au纳米粒子,分别用十二、十四和十六烷基硫醇对Au粒子表面进行修饰,再溶入不同有机溶剂中,制备得到Au纳米粒子/氯仿和Au纳米粒子/甲苯溶液.测试了不同溶液的电导率随溶质浓度的变化规律,发现在整个浓度范围内存在一个临界浓度值.当溶质浓度低于临界浓度值时,溶液的电导率随溶质浓度的增加而迅速增加;而当溶质浓度超过临界浓度值时,溶液电导率的增加缓慢.在本文测试的浓度范围内,当Au纳米粒子分别被十二、十四和十六烷基硫醇修饰时,Au纳米粒子/氯仿溶液的临界浓度值分别约为11.22,7.96和5.47g/L.在相同浓度下,Au纳米粒子外面包裹的烷基硫醇的链长越短,其溶液的电导率越大.在整个浓度范围内,Au纳米粒子/氯仿溶液的电导率均高于Au纳米粒子/甲苯溶液的电导率. 相似文献