纳米复合Y2O3／TiO2的制备、表征及其光催化性能研究

采用溶胶－凝胶法制备复合半导体Y2O3／TiO2,掺入Y2O3会阻碍锐钛矿晶相的出现,掺入浓度越大,TiO2锐钛矿（101）峰强度减小越大,平均晶粒直径与颗粒直径减小,比表面积增大;Y2O3／TiO2具有高热稳定性与高比表面积,由于量子尺寸效应,掺入Y2O3使光催化剂的拉曼峰发生微小位移,在380－460nm范围内,使反射率增强,以亚甲基蓝与甲基橙溶液光 经降解为模型反应,掺入Y2O3,复合光催化剂对亚甲基蓝溶液的光催化脱色降解一级动力学常数明显低于纯TiO2的;掺入5％的10％Y2O3,复合光催化剂对甲基橙溶液的光催化脱色降解一有动力学均常数高于纯TiO2的,掺入浓度太高反而有害,讨论了掺入Y2O3后光物理性质的变化与其光催化活性的关系。     

纳米复合Sb_2O_3/TiO_2的光催化性能研究

采用溶胶-凝胶法制备复合纳米 Sb2O3/TiO2。 Sb2O3掺入浓度越大,催化剂中锐钛矿相含量越高,晶粒直径与颗粒直径越小,比表面积越大。在 380～ 460nm范围内, Sb2O3/TiO2的反射率则减弱,表明光吸收增强。 XPS分析表明：掺入 2％ Sb2O3,出现新的 Ti2p3/2峰,对应于 Ti3＋,占 9.13％;锑以 Sb3＋、 Sb5＋两种形式存在, Sb5＋占 84.42％、 Sb3＋占 17.58％。以亚甲基蓝溶液光催化降解为模型反应,掺入 2％、 5％ Sb2O3,亚甲基蓝溶液的光催化脱色降解一级动力学常数与总有机炭（ TOC）去除率增大。发射光谱证明： Sb2O3的最佳比例为 2％,当其比例大于 2％时,其电子空穴对的复合率升高,光催化活性下降。     

纳米复合Sb2O3/TiO2的光催化性能研究

采用溶胶－凝胶法制备复合纳米Sb2O3/TiO2Sb2O3掺入浓度越大,催化剂中锐钛矿相含量越高,晶粒直径与颗粒直径越小,比表面积越大,在380－460nm,范围内,Sb2O3/TiO2的反射率则减弱,表明光吸收增强,Sb^5＋,占48．42％、Sb^ 占17．58％,以亚甲基蓝溶液光催化降解为模型反应,掺入2％,5％Sb2O3,亚在蓝溶液的光催化脱色降解一致动力学常数与总有机炭（TOC）去除率增大,发射光谱证明,Sb2O3的最佳比例为2％,当其比例大于2％时,其电子空穴对的复合率升高,光催化活性下降。     

La2O3掺杂TiO2光催化剂的制备和性能

采用溶胶-凝胶法制备了La2O3掺杂TiO2纳米光催化剂，并通过XRD、TEM、BET和XPS等手段进行了表征．掺入La2O3后，阻止了TiO2从锐钛矿晶型向金红石晶型的转变，使TiO2的粒径减小，比表面积增大．以甲基橙为光催化降解反应模型化合物，考察了光催化剂的活性．测定了甲基橙在纯TiO2和La2O3掺杂TiO2光催化剂上的吸附常数．考察了pH、H2O2对降解性能的影响．讨论了光催化活性与催化剂性质的关系．     

WO3/TiO2纳米材料的制备及光催化性能

采用溶胶-凝胶法制备WO3/TiO2复合纳米光催化剂,掺入WO3、TiO2锐钛矿101峰的相对强度、平均晶粒直径与颗粒直径均减小,比表面积增大;WO3掺入摩尔比分别为2%、5%、8%时,新的LRS峰位分别出现在797、967及969cm-1;在380-460nm范围内,WO3/TiO2的反射率减小,XPS分析表明,WO3/TiO2晶体中存在W6+、W5+、W4+、和Ti4+、Ti3+。以亚甲基兰的光催化降解为反应模型,掺入WO3后,光催化活性增强,掺入摩尔比为2%时,WO3/TiO2的光催化活性最高。还讨论了光催化活性与性质的关系。     

Nd_2O_3/TiO_2光催化剂的光生羟基自由基和光活性

以硝酸钕和钛酸四正丁酯作为前驱体,采用溶胶-凝胶法制备了Nd2O3/TiO2纳米光催化剂,并通过XRD和BET等手段进行了表征.以对苯二甲酸作为探针分子,结合化学荧光技术研究了光催化剂表面羟基自由基的生成;并以甲基橙为光催化降解反应模型化合物,考察了光催化剂的活性.测定了甲基橙在TiO2和Nd2O3/TiO2(1.0%)光催化剂上的吸附常数.结果表明:Nd2O3掺杂使TiO2的粒径减小,比表面积增大;羟基自由基的生成速率越大,催化剂的催化活性越高.Nd2O3掺杂有利于反应底物在催化剂表面的吸附,Nd2O3的最佳掺入量为Nd/Ti(摩尔比)=1.0%.     

活性炭负载TiO2-Fe3O4磁性光催化剂的制备及性能

采用溶胶-凝胶法制备了易于固液分离的活性炭（AC）负载磁性光催化剂（TiO2-Fe3O4／AC）．样品通过SEM-EDX和X射线衍射法进行表征．通过在紫外光照射下降解亚甲基蓝评价其光催化降解能力．结果表明：负载22％Fe3O4的光催化剂（含20％TiO2和58％AC）的光催化活性最强（120min时亚甲基蓝的降解率达到87％,是纯TiO2的2．7倍）;磁性光催化剂可实现磁分离回收．     

超声微乳法合成TiO2-SiO2催化剂可见光光催化降解亚甲基蓝

采用可见光下亚甲基蓝的光催化降解为模型反应,考察了超声微乳法经钛酸丁酯水解合成的纳米TiO2-SiO2催化剂的性能,并用XRD和BET对催化剂进行了表征。结果表明:硅胶的加入有效地提高了TiO2-SiO2催化剂的热稳定性,抑制了热处理过程中TiO2由锐钛矿相向金红石相的转变和晶粒的长大。随着焙烧温度和TiO2含量的增加,TiO2的晶粒变大,但比表面积减少。TiO2-SiO2的光催化活性明显改善,可见光照射120min,31%TiO2/SiO2催化剂存在下,有84%亚甲基蓝光催化降解。31%TiO2/SiO2催化剂光降解亚甲基蓝的能力大大优于Degussa P-25和纯TiO2,其降解亚甲基蓝的反应速率常数分别为P-25和纯TiO2的8倍和10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.     

Eu~(3 )、Si~(4 )共掺杂TiO_2光催化剂的协同效应

采用溶胶-凝胶-浸渍法制备了Eu/Ti/Si纳米光催化剂,并通过XRD、FT-IR、EPR等进行了表征.结果表明,掺入Eu3 和Si4 ,阻止了TiO2从锐钛矿晶型向金红石晶型的转变,使TiO2的粒径减小,且Eu3 能够促进Si4 进入TiO2的晶格中.以甲基橙为光催化反应模型化合物,考察了光催化剂的活性.测定了甲基橙在不同光催化剂上的吸附常数,探讨了催化剂对甲基橙的吸附机理.Eu3 和Si4 的最佳掺入量分别为wEu=0.03%、wSiO2=39.06%,且Eu3 和Si4 同时掺入TiO2光催化剂产生协同效应.讨论了光催化活性与催化剂性质的关系.     

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.     

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.     

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.     

Thermal decomposition of Me3SnO2PCl2, Me2Sn(O2PCl2)2 and Ph3SnO2PCl2

TG and DTA studies on Me₃SnO₂PCl₂, Me₂Sn(O₂PCl₂)₂ and Ph₃SnO₂PCl₂ were carried out under dynamic argon atmosphere. The results show that the decomposition proceeds in different stages leading to the formation of Sn₃(PO₄)₂ as a stable product. This compound was characterized by IR spectroscopy. Decomposition schemes involving reductive elimination reactions were proposed.     

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.     

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.     

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.