有机金属化合物中碳氢钼(锌)同时快速微量测定研究

本文研究了有机金属化合物中碳氢(锌)的同时快速微量测定的方法。解决了含有挥发性金属残留物的化合物中碳, 氢和金属同时测定的难题, 提高了分析效率, 三元素同时测出仅需15min, 操作简便, 每次取样量为2mg。     

有机锗化合物中碳氢的快速测定

报道了用Co3O4 作覆盖氧化剂分析有机锗化合物中碳氢元素的方法。通过对 9个样品的十几次分析 ,碳、氢的相对误差分别小于± 1.30 % ,4 .4 0 %。方法简便 ,结果稳定可靠 ,可用于含锗有机化合物的碳氢分析。     

高氟有机化合物中碳氢元素的微量测定

本文研究了含高氟有机化合物中碳氢元素微量测定的条件。提出使用高温燃烧及混合氧化剂,以避免四氟化碳的形成。燃烧温度为950～1000℃,氧气流速每分钟为12毫升。     

双核有机金属化合物的光化学反应探析

有机金属化合物是指分子中至少含有一个金属-碳键（M-C键）的化合物,包括含M-C σ-键、M-Cnπ-键、ηn-M-Cn大π-键的化合物.双核金属-金属碳键的有机化合物的光化学反应包括光诱导金属-金属键的断裂、配体的离解与取代、光化学插入反应、光诱导异构化反应、歧化反应等.     

有机钼,钨化合物研究I.FISCHER型卡宾络合物的合成和性质

我们合成了六个新的钼、钨季铵盐[(CO)5MC(O)R]N(CH3)4和钨的卡宾络合物,并研究了它们的某些性质。经元素分析、IR和1H NMR的鉴定,确证了它们的结构。由这些络合物组成的催化体系,其中某些能使单取代乙炔聚合,有的还能使双取代己炔聚合。     

有机金属化合物中二级化学键的理论研究（Ⅲ）：金属原子簇…

应用ＩＣＯＮ８（ＥＨＭＯ）分子轨道方法，讨论了金属原子簇化合物离子「Ｍ３（ＣＯ）９ＣＣＯ」＾２－（Ｍ＝Ｆｅ，Ｒｕ，Ｏｓ」的结构异性及配体在金属原子基平面上的取向，并表明了二级化学键的存在。     

比浊法快速测定电解锌废液中微量氯

电解锌生产流程是封闭循环系统,从锌矿至电解废液,氯离子的检测必不可少。氯离子主要源于矿石及辅料中可溶性氯化物,并不断累积,当流程中氯离子超过100mg·L-1时,就会引起烧极板锌片剥离困难等生产不利因素,废液中的锰(Ⅶ)则来自净化工序,含量一般在10～20g·L-1。用比浊法测定氯离子时产生严重背景干扰,导致氯离子结果偏高。消除锰(Ⅶ)的背景干扰,是采用比浊法快速测定电解锌废液中微量氯的关键。经试验用硫酸亚铁将七价锰还原至无色低价锰,不仅空白值低,还原效果好,30g·L-1硫酸亚铁溶液0.3ml,可还原100mg七价锰至低价,试样加标回收…     

有机金属化合物的电子计数法和结构规则

本文将有机金属化合物的价电子计数法划分为两类,即中性配位体法和封闭壳层配位体法。将(9N-L)结构规则修改为(9N-L+p)规则,并稍加推广,可适用于有机化合物、有机金属化合物、各类原子簇(包括多核有机金属化合物)、硼烷及多层夹心化合物等。     

微量钼(Ⅵ)的质子化壳聚糖富集和分光光度法测定

研究了质子化壳聚糖吸附钼（Ⅵ）的性能和机理。在弱酸性（pH4.5)的NaAc-HAc缓冲溶液）介质中，钼（Ⅵ）以MoO4^2-形式吸附在质子化的壳聚糖上，吸附反应在20min内可达到平衡，饱和吸附容量为18.4mg/g。详细研究了影响吸附过程的有关参数（如介质酸度、吸附速率、吸附容量）和脱附最佳条件。方法用于水体中微量钼（Ⅵ）的富集测定，结果满意。     

不稳定的溶剂配位有机金属化合物单晶取样技术

不少有机金属化合物,特别是有机稀土金属化合物对微量空气、湿气极为敏感,因而它们的取样和分析技术具有一定的特殊性,并有专门介绍这方面技术的报道。最近我们得到一个四氢呋喃配位的有机镥配合物,它在四氢呋喃溶剂中能生成带溶剂配位的无色斜方晶体。当抽去溶剂或在通氩下,将晶体装入玻璃毛细管时,由于晶体在离开母液后失去配位溶剂分子而变成粉状,因而采用一般的取样方法得不到适用于x-射线晶体结构测定的单晶。为此,我们设计了一种新的单晶取样器(见附图),可以成功地取出单晶样品,并测定其晶体结构。该取样器加工简便,取样安全可靠,可连续取样,以便挑选合适的测试样品。现将装置及取样方法介绍于后。     

Carbon Nanotube Supported Molybdenum Carbide as Robust Electrocatalyst for Efficient Hydrogen Evolution Reaction

Molybdenum carbide is considered to be one of the most competitive catalysts for hydrogen evolution reaction (HER) regarding its high catalytic activity and superior corrosion resistance. But the low electrical conductivity and poor interfacial contact with the current collector greatly inhibit its practical application capability. Herein, carbon nanotube (CNT) supported molybdenum carbide was assembled via electrostatic adsorption combined with complex bonding. The N-doped molybdenum carbide nanocrystals were uniformly anchored on the surfaces of amino CNTs, which depressed the agglomeration of nanoparticles while strengthening the migration of electrons. The optimized catalyst (250-800-2h) showed exceptional electrocatalytic performance towards HER under both acidic and alkaline conditions. Especially in 0.5 M H₂SO₄ solution, the 250-800-2h catalyst exhibited a low overpotential of 136 mV at a current density of 10 mA/cm² (η₁₀) with the Tafel slope of 49.9 mV dec⁻¹, and the overpotential only increased 8 mV after 20,000 cycles of stability test. The active corrosive experiment revealed that more exposure to high-activity γ-Mo₂N promoted the specific mass activity of Mo, thus, maintaining the catalytic durability of the catalyst.     

Porous Molybdenum Carbide Nanostructures Synthesized on Carbon Cloth by CVD for Efficient Hydrogen Production

Molybdenum carbide (Mo₂C) is a promising noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER), due to its structural and electronic merits, such as high conductivity, metallic band states and wide pH applicability. Here, a simple CVD process was developed for synthesis of a Mo₂C on carbon cloth (Mo₂C@CC) electrode with carbon cloth as carbon source and MoO₃ as the Mo precursor. XRD, Raman, XPS and SEM results of Mo₂C@CC with different amounts of MoO₃ and growth temperatures suggested a two-step synthetic mechanism, and porous Mo₂C nanostructures were obtained on carbon cloth with 50 mg MoO₃ at 850 °C (Mo₂C-850(50)). With the merits of unique porous nanostructures, a low overpotential of 72 mV at current density of 10 mA cm⁻² and a small Tafel slope of 52.8 mV dec⁻¹ was achieved for Mo₂C-850(50) in 1.0 m KOH. The dual role of carbon cloth as electrode and carbon source resulted into intimate adhesion of Mo₂C on carbon cloth, offering fast electron transfer at the interface. Cyclic voltammetry measurements for 5000 cycles revealed that Mo₂C@CC had excellent electrochemical stability. This work provides a novel strategy for synthesizing Mo₂C and other efficient carbide electrocatalysts for HER and other applications, such as supercapacitors and lithium-ion batteries.     

The Submicrodetermination of Carbon and Hydrogen in organic Compounds by A Gas-Chromatographic Method

Abstract

Preliminary studies on the development of a method for the determination of carbon and hydrogen in 50–100 μg samples of organic compounds are described. The sample is burned over copper oxide in a helium stream and the water formed is converted to acetylene. Separation of CO₂ and acetylene on a silica gel column is followed by combustion of acetylene to carbon dioxide; the two peaks remain separate and are measured by a highly sensitive katharometer.     

二硫化钼纳米片/碳纳米纤维杂化材料的制备及其析氢性能

以碳纳米纤维(CNFs)作为负载基体和反应器采用静电纺丝技术和碳化工艺生长和调控二硫化钼(MoS_2)纳米片。通过改变前驱体溶液浓度来调控纳米片的形貌和结构,利用MoS_2纳米片的高催化活性和CNFs高比表面积、良好的稳定性以及高电导率的协同作用,研究不同形貌和结构的杂化纳米材料在电催化析氢方面的应用,探索杂化材料形貌与性能之间的潜在规律。运用多种分析测试技术对制备得到的纳米杂化材料进行表征,并对所制备的MoS_2/CNFs杂化材料的电催化析氢性能(HER)进行研究,研究表明近似皮芯结构的MoS_2/CNFs-10杂化材料的电催化析氢性能最好,初始析氢过电位在220 mV,Tafel斜率为110m V·dec~(-1)。     

二硫化钼纳米片/碳纳米纤维杂化材料的制备及其析氢性能

以碳纳米纤维（CNFs）作为负载基体和反应器采用静电纺丝技术和碳化工艺生长和调控二硫化钼（MoS₂）纳米片。通过改变前驱体溶液浓度来调控纳米片的形貌和结构,利用MoS₂纳米片的高催化活性和CNFs高比表面积、良好的稳定性以及高电导率的协同作用,研究不同形貌和结构的杂化纳米材料在电催化析氢方面的应用,探索杂化材料形貌与性能之间的潜在规律。运用多种分析测试技术对制备得到的纳米杂化材料进行表征,并对所制备的MoS₂/CNFs杂化材料的电催化析氢性能（HER）进行研究,研究表明近似皮芯结构的MoS₂/CNFs-10杂化材料的电催化析氢性能最好,初始析氢过电位在220 mV,Tafel斜率为110 mV·dec^-1。     

Simultaneous Voltammetric Determination of Molybdenum and Copper in Manganese Compounds

 Adsorptive voltammetry was employed for the determination of copper and molybdenum in manganese compounds. As working electrode the hanging mercury drop electrode (HMDE) was used. The method was applied in aqueous solutions of MnCl₂ and Mn(NO₃)₂, as well as in pre-treated manganese dioxide and manganese ores. The detection limits are 3 μg/g for copper and 5 μg/g for molybdenum in the sample. The RSDs at concentration level of 8 μg/g are 2.2 and 3.2% for copper and molybdenum, respectively.     

Coupling of SPME and GC-AED for the Determination of Organometallic Compounds

 The solid-phase microextraction (SPME) technique coupled with gas chromatography and atomic emission detection was successfully applied for the determination of selected organometallic species of Pb, As and Hg in aqueous samples. To obtain a high extraction yield, the SPME conditions were optimised for each element by fibre selection and varying the exposure time, stirring rate, pH range and desorption time. All the organometallic compounds tested were extracted from the aqueous phase using SPME. The preconcentration factors attained ranged between 40 and 150, depending on the compound. Detection limits in the pg/L and ng/L ranges were achieved. Received January 18, 2000. Revision April 11, 2000.     

Bridging the Gap between Coordination and Cluster Compounds: Unusual Bonding Modes for Zinc

Inner virtue : The reaction of [Mo⁰(GaCp*)₆] with ZnMe₂ yields the novel multinuclear zinc system [MoZn₁₂Me₉Cp*₃] which geometrically resembles a classical Wade–Mingos cluster (with an interstitial molybdenum atom, see picture). In reality, its electronic structure features little direct Zn? Zn bonding, relying instead on Mo? Zn three‐center, two‐electron bonds spanning the body diagonals of the approximately icosahedral framework.

     

Determination of Molybdenum in Human Urine by Spectrophotometric Method using Thiazolylazo Compounds as Chromogenic Reagents

ABSTRACT

Four azo compounds based on diazotization of 2-aminobenzothiazole have been synthesized and characterized by elemental analysis as well as different spectroscopic techniques. The potentiality of the prepared compounds as new chromogenic reagents for the spectrophotometric determination of Mo⁶⁺ was studied by extensive investigation of optimum conditions favouring the formation of the coloured complexes. Beers law is obeyed in the concentration range 0.2-8.5 μg ml^?1 whereas Ringbom optimum concentration range was 0.8-7.5 μg ml^?1. The detection limit was 0.05 μg ml^?1. The molar absorptivity and Sandell sensitivity of the formed complexes are calculated. The effect of interfering ions on the determination of Mo⁶⁺ was investigated. The relative standard deviations for six replicate determinations of 5.0 μg ml^?1 of Mo⁶⁺ are 1.23, 1.47, 1.05 and 1.38 % using reagents I, II, III and IV, respectively. The proposed method has been applied to investigate the amount of Mo⁶⁺ in human urine samples. The molybdenum levels found between 0.5-2.1 μg/100 ml.     

水蒸气重整生物质裂解油及其模型分子制氢

随着能源枯竭和环境日益恶化,利用可再生的生物质裂解油或其模型分子重整制氢逐渐引起人们重视。本文结合国内外重整制氢的研究进展,从催化剂、反应过程和反应机理三个方面对生物质裂解油及其模型分子(乙醇、乙酸、乙二醇、丙三醇、葡萄糖和苯酚等)水蒸气重整制氢研究现状进行了回顾。在重整催化剂方面主要对贵金属和过渡金属催化剂的研究进展进行了总结,对一些新的重整过程如液相重整等也进行了介绍。在反应机理方面主要是对乙醇、乙酸、乙二醇和葡萄糖在重整反应中的反应路径进行了归纳。此外,对水蒸气重整反应中遇到的问题如积碳和副产物的产生等也进行了详细的分析,并对生物质制氢未来发展的方向进行了展望。