Cu/SiO2表面性质对甲醇脱氢反应性能的影响

甲醇催化脱氢是将甲醇转化为其它有机化学品的一条有效途径,该反应的产物依反应条件以及催化剂不同有可能是无水甲醛、甲酸甲酯或CO’‘－”．很多研究结果表明铜基催化剂对甲醇脱氢反应表现出较好的催化性能’‘－”,但催化剂的表面结构对其反应性能的影响以及反应过程中由于催化剂结构变化引起的活性和选择性的变化规律还缺乏深入研究．本文以Cll／Sic。为研究对象,考察了制备方法对催化剂甲醇脱氧反应性能的影响．1实验部分1．1催化剂制备负载型催化剂以微球型Sic。作为载体（BET比表面积3635mZ·g－‘）,分别以钢氨溶液和硝酸铜…     

电阻率与强度性能的关联及铜合金性能分区

铜合金以低电阻率为特征,由于电阻率与强度存在着共同的微观结构机理,两者往往协同变化,而导致难以对合金进行性能的全面评估和选材.本文以Cu-Ni-Mo合金作为研究对象,以团簇结构[Mo_1-Ni_(12)]构建固溶体的近程序结构模型,解析了电阻率和强度依赖于成分的定量变化规律,并定义了拉伸强度/电阻率的值为代表合金本质特性的"强阻比",得到了完全固溶态Cu-Ni-Mo合金的强阻比为7×10~8MPa/?·m,完全析出态的强阻比为(310—490)×10~8MPa/?·m.进而应用强阻比对常用铜合金进行了性能分区,给出铜合金材料选材的依据,得出了基于Cu-(Cr, Zr, Mg, Ag, Cd)等二元基础体系的铜合金适用于高强高导应用,而基于Cu-(Be, Ni, Sn, Fe, Zn, Ti, Al)等为基础二元体系的铜合金不能实现高强高导.该强阻比为310的特征性能分界线的发现为合金性能的全面评估提供了量化依据,可指导高强高导铜合金的选材和研发.     

激光能量对激光诱导Cu等离子体特征辐射强度、电子温度的影响

利用Nd:YAG激光(波长1 064 nm,脉宽10 ns)烧蚀金属Cu靶获得等离子体 .改变激光脉冲能量,观测到Cu的原子谱线和离子谱线随激光脉冲能量有不同的变化关系, 但都在330 mJ/pulse时,谱线强度达到最大,随后在330 mJ～370 mJ/pulse间出现一小平台 ,能量继续增加,各谱线强度减小.同时,使用烧蚀Cu靶产生的五条原子谱线(465.11 nm,5 10.55 nm,515.32 nm,521.82 nm,529.25 nm)的相对强度,在局部热力学平衡近似下,利用B oltzmann图的最小二乘法拟合,测定了不同激光能量下Cu等离子体的电子温度.随激光能量的增加,电子温度近似单调地从1.02×104 K上升到1.46×104 K后,反而有所下降.     

表面活性剂碳化法合成Fe3O4/C复合物及其电化学性能

以水热法合成的包覆油酸的α-Fe₂O₃粒子为前驱体, 在氩气下500 °C煅烧1 h, 得到Fe₃O₄/C纳米复合物. 用傅里叶变换红外(FTIR)光谱, X射线衍射(XRD), 扫描电镜(SEM), X射线能量散射(EDX)谱, 高分辨透射电镜(HRTEM), 元素分析, 循环伏安(CV)和恒流充放电测试等方法对材料的结构、形貌、成分及电化学性能进行了表征. 结果表明: 所制备的Fe₃O₄/C复合物呈长约200 nm, 粗约100 nm的纺锤形, 表面碳层厚约1-2 nm, 碳含量为1.956%(质量分数); 这种复合物作为锂离子电池负极材料具有很好的循环稳定性(在0.2C (1C=928 mA·g^-1)循环80次后具有691.7 mAh·g^-1比容量)和倍率性能(在2C循环20次后依然有520 mAh·g^-1比容量). 相对于未包覆的商业Fe₃O₄粒子, 复合物显著提高的电化学性能是由于碳包覆能防止粒子聚集, 提高导电性以及稳定固体电解质界面(SEI)膜.     

动态氢气泡/牺牲铜模板法制备蜂窝AuPtCu电催化剂用于甲酸氧化

微/纳多孔金属材料具有高比表面积等优点，在电化学等领域广受关注.本工作通过动态氢气泡模板法，在镀金玻璃碳电极（Au_pla/GCE）上电沉积三维蜂窝状多孔纳米AuPtCu （3DHPN-AuPtCu）复合材料，再阳极溶出Cu，制备了3DHPN-AuPt_Cu/Au_pla/GCE.采用循环伏安法（CV）、金相显微镜、扫描电子显微镜、能量色散谱和电感耦合等离子体-原子发射光谱等手段表征了相关修饰电极.所制3DHPN-AuPt_Cu/Au_pla/GCE在含0.2 mol/L HCOOH的0.5 mol/L H₂SO₄水溶液中，电催化氧化甲酸的峰电流密度为12.5 mA·cm_Pt^-2（CV，-0.3～1.0 V，50 mV/s），优于有关对照电极和很多已报道的Pt复合物修饰电极，表明通过这种动态氢气泡/牺牲铜双模板法可制备出电催化性能优异的金属蜂窝结构.     

Development of nanosized oxide composites for catalytic CO oxidation

Abstract

Effect of composition and morphology on the catalytic activity in CO oxidation of Co-, Cu-, Ce-containing oxide materials prepared by citrate method has been studied. It was shown that composites consist of well-dispersed oxides Со₃O₄, CuO and CeO₂ with average crystallite sizes 13–24?nm, 14–26?nm and 3–7?nm, respectively. It was established that Co-, Cu-, Ce-oxide nanocomposites demonstrated higher catalytic activity in CO oxidation in comparison with individual oxides. The ternary oxide system Со₃O₄–CuO–СеO₂ (Со:Cu:Се=10:1:1) was found to possess the highest catalytic activity due to formation finely dispersed particles of CuO and СеO₂ oxides simultaneously with nanosized Со₃O₄ species and formation of large quantity of mobile oxygen at the interfaces between the oxide nanoparticles.     

A water-stable Cu(II)-based coordination polymer for clinical nursing effect on schizophrenia by inhibiting over-activity of the dopaminergic neurons

ABSTRACT

In this study, we use two methyl-substituted organic ligands 5-methylisophthalic acid (H₂mica) and 1,3-bis(5,6-dimethylbenzimidazol-1-yl)propane (L) as the co-linkers to produce a water-stable Cu(II)-containing coordination polymer {[Cu(mica)(L)₂]·H₂O}_n (1) under the solvothermal condition. Furthermore, the protective effect of 1 on schizophrenia mice was evaluated in vivo. Firstly, the relative expression level of the dopamine transporter in the mesencephalic limbic system of schizophrenia was detected with RT-PCR. Then, the content of the dopamine released by the mesencephalic limbic system was measured with ELISA assay. Annexin V-FITC/PI apoptosis was used to detect the percentage of the apoptotic dopaminergic neuron. The relative expression of the Wnt1-Nkx2.2 was measured with RT-PCR.     

A distinct approach for the rapid synthesis of homoallylic amines starting directly from nitro compounds in water

Three-component reactions of nitroarenes, benzaldehydes, and allyltributylstannane using indium in dilute aqueous HCl at room temperature afford the corresponding homoallylic amines in high yields within 5-10 min. The conversion in one-pot synthesis involves the following steps: (i) reduction of nitro compounds to amines, (ii) formation of imines from amines and aldehydes, and (iii) allylation of imines.     

Copper perchlorate hexahydrate: a highly efficient catalyst for the cyanosilylation of aldehydes

Cu(ClO₄)₂·6H₂O has been found to be an efficient catalyst for cyanosilylation reaction of aldehydes in THF at room temperature with low catalytic loading (1.0 mol%) in short reaction time (mostly within 10 min). Copyright © 2008 John Wiley & Sons, Ltd.