纳米复合材料CoFe2O4/SiO2的制备和表征

采用溶胶-凝胶法制备了(CoFe2O4)x/(SiO2)1-x纳米复合材料. 利用TG/DTA, XRD和Mssbauer效应研究了热处理过程中干凝胶的变化及样品的结构、晶粒尺寸和磁性. 结果表明, 随着SiO2含量的增加, 样品中CoFe2O4的晶粒尺寸和内磁场逐渐变小, 并从磁有序状态转变为超顺磁状态.     

导电聚苯胺与磁性CoFe2O4纳米复合物的制备与表征

在利用HNO3酸化处理CoFe2O4磁性纳米粒子使其表面离子化、分散性得到改善的基础上, 采用原位聚合法制备了具有电磁功能的聚苯胺/CoFe2O4 (PANI/CoFe2O4)纳米复合物. 借助TEM, XRD, FT-IR, TG, 四探针电导率仪、VSM(振动样品磁强计)等分析手段研究了复合物的形貌、结构、热稳定性及电磁性能. 结果表明, 处理过的CoFe2O4磁性纳米粒子可形成分散均匀的PANI/CoFe2O4纳米复合物, CoFe2O4以25 nm左右的粒子分散于聚苯胺基体中; PANI与CoFe2O4之间存在化学键合作用, 正是这种作用使复合物热稳定性得以提高; 复合物同时具有导电性和磁性能, 且随CoFe2O4含量变化而变化.     

CoFe2O4/CdS纳米复合物的制备、表征及其声催化降解有机染料污染物

在低温(200℃)下采用一步水热分解CoFe2O4纳米粒子表面的镉二硫代氨基甲酸酯配合物制备了磁性CoFe2O4/CdS纳米复合物,运用X射线衍射、红外光谱、扫描电镜、X射线能量散射谱、紫外-可见光谱、透射电镜(TEM)、N2吸附-脱附、X射线光电子能谱和振动样品磁强计对所制样品进行了表征.TEM结果表明,CoFe2O4/CdS纳米复合物由几乎均一的约20nm球形纳米粒子组成.光吸收谱显示该样品的带隙为2.24 eV,很适合用于声/光催化降解有机污染物.在紫外光照射下评价了CoFe2O4/CdS纳米复合物的声催化H2O2辅助降解甲基蓝、罗丹明B和甲基橙反应活性.结果表明,该纳米复合物对这3种染料均表现出很好的声催化活性(5-9 min内完全降解).另外,比较实验结果表明,CoFe2O4/CdS纳米复合物是一个比纯CdS更高效的声催化剂.因此,纳米复合是一种非常好的提高CdS声催化活性的手段.该CoFe2O4/CdS纳米复合物表现出的磁性使其很容易从反应混合物中分离出来而重复使用.     

纳米复合材料CoFe2O4/CD-SBA-15的制备与表征

为制备在磁性环境下容易分离的新型吸附材料,制备了CoFe2O4/β-CD-SBA-15纳米复合材料,采用X射线衍射(XRD)、红外光谱(FT-IR)、透射电镜(TEM)、比表面测定仪(BET)和振动样品磁强计(VSM)对纳米复合材料的结构与性能进行表征.研究表明:CoFe2O4分散在β-CD-SBA-15的骨架和孔道里...     

导电聚苯胺与磁性CoFe2O4纳米复合物的合成及其电磁性能

在利用HNO3处理CoFe2O4磁性纳米粒子使其表面离子化、分散性得到改善的基础上, 采用苯胺在其表面原位聚合, 制备了具有电磁功能的聚苯胺(PANI)/CoFe2O4纳米复合物. 借助TEM、XRD、FT-IR、四探针电导率仪和VSM(振动样品磁强计)等分析手段研究了复合物的形貌、结构及其电磁性能. 结果表明, CoFe2O4以25 nm左右的粒子分散于聚苯胺基体中, 被其完全包覆, CoFe2O4与PANI之间存在化学键合作用; 复合物同时具有电性能和磁性能, 其导电率随CoFe2O4含量增加而降低, 饱和磁化强度随之升高, 而矫顽力在所研究的范围内则先增大而后又减小, 且均高于CoFe2O4的矫顽力.     

基于Nafion-氧化石墨烯复合物/硫堇/纳米金构建过氧化氢传感器的研究

利用Nafion(全氟聚苯乙烯磺酸溶液)-氧化石墨烯复合物、硫堇和纳米金构建了H2O2酶传感器。首先将氧化石墨烯分散在体积分数0.2%Nafion溶液中制得Nafion-氧化石墨烯的复合物,并将其固定在玻碳电极表面,通过静电吸附将带正电荷的硫堇吸附到Nafion-氧化石墨烯复合膜修饰的玻碳电极表面,再利用静电吸附将纳米金修饰于电极上,通过纳米金来固定辣根过氧化物酶从而制得H2O2传感器。用循环伏安法和计时电流法考察该修饰电极的电化学特性。H2O2浓度为5.5×10-6~1.0×10-3mol/L时,酶电极的响应电流值与H2O2的浓度呈良好的线性关系,检出限为1.80×10-6mol/L。     

ZnFe2O4/TiO2纳米管阵列电极的制备及光电催化降解苯酚的研究

采用阳极氧化法和电沉积法制备出具有可见光响应的ZnFe2O4/TiO2纳米管阵列电极.用环境扫描电子显微镜(ESEM)、X-射线衍射(XRD)和透射电子显微镜(TEM)对制备的ZnFe2O4/TiO2纳米管阵列电极的表面形貌和结构进行了表征.结果表明,该方法成功地将ZnFe2O4纳米颗粒均匀分散在TiO2纳米管中,分布在管口处的较少.同时,详细讨论了反应物浓度、沉积时间、循环次数、沉积电压对ZnFe2O4/TiO2纳米管阵列电极性能的影响.通过在可见光下降解苯酚评价了复合电极的光催化活性,实验结果表明:由于ZnFe2O4和TiO2之间的协同效应,复合电极的光响应范围扩展到了可见光区域,光电催化活性提高1.5～2倍.     

磁性TiO2/CoFe2O4纳米复合光催化材料的制备

以磁性CoFe2O4为核,采用改进的溶胶-凝胶法,制备了磁性TiO2/CoFe2O4纳米复合光催化材料.利用VSM(振动样品磁强计)技术对其磁性能进行了研究,结果表明:由该法所得的TiO2/CoFe2O4纳米复合光催化材料的饱和磁化强度虽稍弱于纯CoFe2O4纳米材料,但其矫顽力则优于CoFe2O4.TEM、XRD、UV-Vis等的结果表明,该纳米复合材料中的TiO2为锐钛矿结构;与TiO2相比,纳米复合材料对光的吸收拓展到了整个紫外-可见区,且吸收强度大大增强.对染料废水光催化降解的模拟研究表明,该复合材料在紫外光下,6 h可以使亚甲基蓝染料溶液的脱色率达95%,且重复使用3次时染料溶液的脱色率仍能保持在90%,明显优于纯TiO2.     

基于聚亚甲基蓝-碳纳米管复合膜固载血红蛋白的H2O2生物传感器

采用吸附和电化学聚合修饰方法,制得了聚亚甲基蓝-碳纳米管聚合膜玻碳电极(PMB-MWNTs/GCE),再将血红蛋白(Hb)固定在PMB-MwNTs/GCE表面,制备了稳定的Hb/PMB-MwNTs//GCE的H2O2生物传感器,并用循环伏安法对修饰电极的生物电催化行为进行了表征.研究结果表明,固定在PMB-MWNTs/...     

基于磁性Fe_3O_4/Au-Pt纳米复合物构建甲胎蛋白免疫传感器的研究

制备了磁性Fe3O4/Au-Pt纳米复合物,将该纳米复合物修饰在玻碳电极表面,用牛血清蛋白封闭电极表面非特异性吸附位点。通过循环伏安法对电极的制备过程以及响应性能进行表征。实验结果表明,该修饰电极对甲胎蛋白(AFP)有良好的电流响应,在甲胎蛋白浓度为0.05~1.0ng/mL和1.0~100.0ng/mL两个范围内,分别呈良好的线性,检出限为0.01ng/mL。该免疫传感器制备方法简单,灵敏度较高,有望应用于临床医学中检测人体血清中甲胎蛋白含量。     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Formal [(2+2)+2] and [(2+2)+(2+2)] nonconjugated dienediyne cascade cycloadditions

[reaction: see text] Fluoranthene 2 and heptacycle 3 are easily accessible from the reaction of diyne 1 and norbornadiene (NBD) in the presence of the rhodium catalyst. The unusual [(2+2)+(2+2)] adduct 3 was confirmed by the X-ray crystal structure analysis.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Die Photoionenspektren von SCl2, S2Cl2 und S2Br2

Photoionization Mass Spectra of SCl₂, S₂Cl₂, and S₂Br₂ Photoionization mass spectra of SCl₂, S₂Cl₂, and S₂Br₂ have been measured. Heats of formation, bond energies, and ionization potentials of fragments have been calculated from appearance potentials.