The role of co-adsorbed O2 on the catalytic reduction of NO with C2H5OH on the surface of Pt(3 3 2)

The influence of pre-dosed O₂ on the catalytic reduction of NO with ¹³C₂H₅OH on the surface of stepped Pt(3 3 2) was investigated using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). We show that the oxidation of ¹³C₂H₅OH with O₂ is a very effective reaction, occurring at 150 K and giving rise to acetate. The presence of NO does not lead to any evident oxidation of ¹³C₂H₅OH irrespective of the annealing temperature. For the case of O₂ + ¹³C₂H₅OH + NO co-adlayers, oxidation of ¹³C₂H₅OH also takes place at 150 K. However, no new surface species that are supposed to be an intermediate for the production of N₂ are detected.The influence of O₂ on the production and desorption of N₂ is intimately related to both O₂ and ¹³C₂H₅OH coverage. The presence of pre-dosed O₂ does not greatly promote N₂ desorption. In fact, N₂ desorption is suppressed quantitatively with increasing O₂ coverage, after which unreacted, or left-over O atoms appear and remain on steps. It is concluded that the presence of pre-dosed O₂ does not play a role of activating reactants in the catalytic reduction of NO with ¹³C₂H₅OH on the surface of Pt(3 3 2).     

Synthesis of tungsten carbide nanocrystals and their electrochemical properties

Tungsten carbide (WC) nanocrystals have been prepared by a solvothermal method with Mg as the reductant and WO₃ and anhydrous ethanol as the precursors. The effects of time and temperature on the synthesis of WC were investigated and a probable formation mechanism was discussed. The obtained WC nanocrystals were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy and electrochemical methods. Hexagonal closepacked WC was successfully synthesized when the temperature was as low as 500°C. The content of carbon was more than that of W, indicating that the composition of the treated sample was C and WC only. The diameters of WC nanocrystals were ranged from 40 nm to 70 nm and the nanocrystals were dispersed on carbon films. The electrochemical measurements reveal that WC nanocrystals obviously promote Pt/C electrocatalytic ability for the oxygen reduction reaction. __________ Translated from Chinese Journal of Catalysis, 2008, 29(7) (in Chinese)     

Phase and shape controlling of MnS nanocrystals in the solvothermal process

MnS nanocrystals with different phases and shapes were prepared through solvothermal synthesis. The products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV–vis absorption and photoluminescence (PL) spectra. The solvent and reaction time played an important role in controlling the phase and shape of MnS nanocrystals. The possible mechanism of the shape evolution was investigated, which revealed that the crystal growth along the unique c axis of γ-MnS resulted in the rod-like MnS at the primary period, and the tetrahedral crystal seed of β-MnS with zincblende structure resulted in the interlinking of MnS rods, so the zigzag and three-branched and palm-like MnS appeared; with increasing reactive time the thermodynamically stable spherical α-MnS was favored through the Ostwald ripening process. The PL results showed that the intensity of γ-MnS was much weaker than that of α-MnS, and the trap state emissions of γ-MnS at 470 and 482 nm, respectively, disappeared, which might be ascribed to the difference of the shapes between the sphere and the rod or branch.     

一个富路易斯碱位配合物的合成、结构及对痕量Ag+的荧光检测

通过溶剂热方法合成了一个由氢键拓展的携带路易斯碱位的三维超分子配位聚合物：{[Cd（HTZ-IP）（HPYTZ）（H₂O）₂]·5H₂O}_n（HTZ-H₂IP=5-（5-四氮唑基）间苯二甲酸;HPYTZ=3,5-（4-吡啶基）-1,2,4-三唑]。X射线单晶衍射结果表明,中心镉离子由含氮杂环羧酸配体和富氮辅助配体连接成"有悬挂手臂"的一维链,而链间则凭借配位水和2个配体的氢键作用拓展成三维超分子化合物。有趣的是配合物存在大量裸露的未配位的N原子,此N原子具有路易斯碱性质,能与路易斯酸性质的Ag⁺有效结合,从而引起配合物的荧光猝灭。该性质能在无色溶液中有效检测10^-4~10^-6 mol·L^-1范围内的痕量Ag⁺离子。     

两个具有Sn_4O_4梯状结构二丁基锡羧酸酯的微波溶剂热合成、结构和体外抗癌活性

在甲醇微波溶剂热中,二丁基氧化锡分别与4-甲基苯甲酸、4-二甲氨基苯甲酸反应,合成了2个具有梯形结构的二丁基锡羧酸酯[(μ3-O)(μ2-OMe)(n-Bu2Sn)2(O2CR)]2(R=4-Me-C6H4(1),4-Me2N-C6H4(2)),并对其进行了元素分析、IR和(1H,13C和119Sn)NMR光谱表征。X射线晶体衍射分析表明,化合物1、2具有Sn4O4构筑的3个四元环梯形骨架平面结构,μ3-O桥联2个环内梯锡和1个环梯端锡原子,此外,甲醇氧还以μ2-O桥联1个环内梯锡和1个环梯端锡原子,锡与配基原子构成畸形三角双锥六面体。化合物对人结肠癌(HT-29)、肝癌细胞(Hep G2)、乳腺癌(MCF-7)、鼻咽癌(KB)和肺癌细胞(A549)均显示出比临床使用的顺铂还强的抗癌活性。     

溶剂热法制备钴微球及其表征

<正>0引言过渡金属钴以及它的一些氧化物,以其特殊的电、磁和光学性能被广泛应用到信息存储[1]、催化剂[2]、磁光材料[3]、铁磁流体[4]以及生物医学[5]等诸多领域。前人曾经用羰酰钴热解法[6-7]、γ射线照射法[8]、光刻气相沉积法[9]、电化学沉积法[10]和金属盐溶液的     

Controlled Synthesis of Sea-urchin-like ZnO Nanomaterials with the Aid of Ethylene Glycol Using a Solvothermal Method

Sea-urchin-like ZnO nanomaterials were successfully synthesized by decomposition of zinc acetate precursor in the presence of sodium hydroxide and ethylene glycol(EG) in an ethanol solution using a solvothermal method at 180 ℃ for 12 h.The crystalline phase and morphology of the resultant nanomaterials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),selected-area electronic diffraction(SAED) and high-resolution electron microscopy(HRTEM).Interestingly,the sizes and prod length of the samples can be easily tuned by changing the amount of directing agent EG and keeping other reaction conditions unchangeable.On the basis of our experimental outcomes,EG-controlled-nucleation-growth formation mechanism was proposed to correspond for the sea-urchin-like ZnO growth processes.And the photoluminescence(PL) spectra of the as-selected samples were measured at room temperature,presenting two emission peaks centered at～388 and 480 nm.     

Ligand-assisted, copper-catalyzed enantioselective benzylic amination

Several classes of ligands, including α-amino acids, diamines, diphosphines, bis-oxazolines, and diimines, support efficient copper-catalyzed amination of benzylic hydrocarbons by anhydrous chloramine-T. Catalysts derived from homochiral ligands, particularly chiral diimines, effect aminosulfonation with low to moderate enantioselectivity.