新型纳米SnO2-CuO复合氧化物负极材料的制备与电化学性能

以SnCl4·5H2O、Cu(NO3)2·3H2O和NH3·H2O为原料,采用化学共沉淀法制备了纳米SnO2-CuO复合粉末.运用热重和差热分析、X射线衍射、扫描电镜和红外光谱等手段对合成粉末进行了表征.将合成粉末作为锂离子电池负极材料,研究了其充放电容量、循环性能和交流阻抗等电化学性能.结果表明,采用化学共沉淀法可以得到平均粒度为87 nm的SnO2-CuO粉末.在SnO2中掺入CuO,并没有改变SnO2的结构,但能够有效抑制SnO2粒子的长大.纳米SnO2-CuO粉末的可逆容量可以达到752 mAh·g-1,经60次循环后,纳米SnO2-CuO粉末的容量保持率分别为93.6%,优于纳米SnO2(92.0%),说明掺杂CuO改善了纳米SnO2的循环性能.     

Characteristics of permittivity and permeability spectra in range of 2-18 GHz microwave frequency for La1-xSrxMn1-yByO3 （B=Fe, Co, Ni）

Doped LaMnO3 has unusual electromagnetic properties, which makes it possible for this material to be used for absorbing microwave. LaMnO3 systems doped by Sr at site A and Fe or Co, Ni at site B were prepared by sol-gel as an microwave absorption material and their permittivity and permeability spectra were measured by microwave vector network analyzer in the frequency range of 2-18 GHz. A novel phenomenon is discovered that the complex permittivity, complex permeability and electromagnetic loss tangent have suddenly a step change at a certain frequency and the step-change frequency is relevant to content of Sr and Fe or Co, Ni. The samples show mainly dielectric loss when microwave frequency is smaller than the step-change frequency, and mainly magnetic loss when larger than that frequency. It is indicated that anti-ferromagnetic clusters in the material can absorb energy quantum of microwave electromagnetic field to change into ferromagnetic clusters because they can overcome higher energy barrier when the frequency of incident microwave reaches a certain value.     

Photocatalytic degradation of dimethomorph on nanometer titanium dioxide by silver depositing in aqueous suspension

A series of catalysts of nanometer TiO2 were prepared by silver depositing. The photocatalytic degradation of dimethomorph in an aqueous suspensions by silver depositing with nanometer titanium dioxide as catalyst was investigated by radiation of UV-light and sunlight. A pseudo-first-order kinetic model was used to describe the results. The effects of the dosage of catalyst, oxidant, pH and radiation source on degradation were examined. The experimental results show that the decomposed rate of DMM is 94% when the dosage of catalyst is 1.25 g/L and the concentration of DMM is 100 mg/L under the conditions of solution pH of 7, the air flow of 1.5 L/min and shining for 5 h by UV-light. When it is shined by sun-light under the same condition, the decomposed rate of DMM is 48 %.The mechanism of decomposition was discussed based on the data by analysis of LC-MS.     

二卤三芳基锑化合物的合成和表征

以三芳锑与卤素反应制备二卤三芳基锑Ａｒ３ＳｂＸ２（Ａｒ＝Ｃ６Ｈ５，ｐ－ＣｌＣ６Ｈ４；Ｘ＝Ｂｒ，Ｃｌ），通过元素分析、红外光谱测定、Ｘ射线衍射及热分析，对化合物进行了表征，探讨了有关热分解过程。结果表明，化合物均为白色晶体，熔点为２２０℃以下，其热分解区域为１８６～３５０℃，溶解于一般有机溶剂，属高分子聚合物优良阻燃添加剂或阻燃剂的中间体。     

Oxygen reduction on teflon-bonded carbon electrode

1　INTRODUCTIONOxygenreduction (OR)inconcentratedKOHsolutionisanimportantprocessinvolvedinalkalinefuelcellsandmetal airbatteries .SomefundamentalstudiesofthekineticsandmechanismsofORincon centratedalkalineelectrolytesthoughrelativelylimit ed .Inalkalineelectrolytes ,OR proceedsbytwopathwaysasfollows :1) 4electrons (4e) pathwayleadingdirectlytoOH- ;2 ) 2electronspathwaywithhydrogenperoxideasintermediateorfinalproducts ,dependingonelectrodesurfacestatesuchastheoxy genadsorption ,oxideco…     

电沉积法制备纳米SnO_2薄膜

采用一种电沉积法室温下制备纳米SnO2薄膜。经研究得到了电沉积SnO2薄膜的最佳工艺条件:电流密度、电沉积时间、主盐浓度、游离酸浓度分别为i=8 mA.cm-2,t=120 m in,c(SnC l2)=0.02 mol/L,c(HNO3)=0.03 mol/L。用X射线衍射、红外光谱和扫描电镜、透射电镜等对薄膜的物相和微观结构、表面形貌等进行了研究。结果表明,室温下干燥得到的薄膜由SnO2.xH2O组成,但经过400℃热处理后,逐渐转变成结晶较为完整的四方结构SnO2薄膜,薄膜的表面较为平整、呈多孔状,薄膜粒径大小为8~20 nm。     

反胶束微乳法制备无机功能纳米材料

介绍了微乳法制备无机纳米粒子的一般实验室方法 ,讨论了影响粒径及其分布的有关因素。比较了微乳液法与传统的制备方法的优劣 ,探讨了无机功能纳米材料研究进展并提出了今后研究工作的展望。     

纳米SnO_2的微波辅助固相合成和电化学性能

以SnC l4.5H2O和NaOH为起始原料,用微波辅助固相法合成了纳米SnO2。研究了微波输出功率、微波作用时间对合成产物结构和粒度的影响。采用X射线衍射分析、透射电镜以及电化学测试等手段对合成产物进行了表征。结果表明,微波输出功率、微波作用时间对合成产物结构和粒度有重要影响。当微波输出功率为350W,微波辐射时间为20 m in时,可以得到粒度大小为20 nm左右,而且分布均匀的纳米SnO2。通过该方法制备的纳米SnO2,可逆容量达到760 mA.h.g-1,0.1 C和0.5 C进行充放电时,60次循环后的容量保持率分别为92%和83%,说明该法制备的纳米SnO2是一种很有前途的锂离子电池负极材料。     

3-羟基-4-甲氧基苯甲醛的合成与表征

以对羟基苯甲醛为原料,经溴代、甲基化和水解3步反应合成了异香兰素,改进并优化了合成路线。溴代采用三氯甲烷作为溶剂,在0℃的条件下反应6 h,n(对羟基苯甲醛)∶n(溴素)=1∶1.05;确定了水解反应的最佳条件:氯化亚铜作催化剂,于130℃反应4 h。反应总收率达62%以上。用IR,1HNMR确证了中间体和产物的结构。     

4-(3,4-二氯苯基)-1-萘满酮合成述评

综述了4-(3，4-二氯苯基)-1-萘满酮的应用及合成方法，对不同路径的原料、催化剂及产率进行了介绍，并对这几种合成路径进行了比较。结果表明采用1-萘酚和邻二氯苯为原料，无水AlCl3作催化剂是一条理想和合成路线。