Ni-MoS2/γ-Al2O3催化剂的制备及其光催化性能研究

采用共沉淀结合水热合成方法,以γ-Al2O3为载体,制备出Ni-MoS2/γ-Al2O3复合催化剂.采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)等方法对样品的结构与形貌进行表征.研究了MoS2负载量、煅烧温度对Ni-MoS2/γ-Al2O3复合催化剂光催化降解罗丹明B性能的影响,并考察了催化剂的循环使用性能.结果表明:负载量为30wt;,煅烧温度为300℃的复合催化剂Ni-MoS2/γ-Al2O3表面的MoS2纳米片兼具有良好的结晶度和均匀分散性,其纳米片尺寸约为200nm.可见光下,Ni-MoS2/γ-Al2O3(MoS2 30wt;/Ni 5wt;)复合催化剂对罗丹明B的降解效率能达到100;,且循环使用5次后,对罗丹明B的降解效率仍能够达到88.9;.     

二硫化钼纳米片修饰聚氨酯海绵及吸油性能研究

以二硫化钼( MoS2)粉末为原料,采用超声辅助液相剥离法制备了MoS2纳米片,通过MoS2纳米片和聚二甲基硅氧烷( PDMS)依次修饰聚氨酯( PU)海绵,制备了疏水亲油性质的PU-MoS2吸油材料,并测试了其接触角和吸油性能。结果表明,所制备的PU-MoS2海绵有着优良的疏水亲油性能和较强的吸油能力。对不同的有机液体,PU-MoS2海绵分别能够吸取自身重量12~86倍的有机溶剂。尺寸较小MoS2纳米片修饰制备的PU-MoS2海绵具有较高的吸油能力。此外,PU-MoS2海绵在重复使用20次后仍能保持强的吸油能力,表明其可循环利用,具有良好的应用前景。     

Ag/MoS2复合纳米材料对香精分子的SERS效应

采用正丁基锂插层法在室温下制备了MoS2纳米片悬浊液;同时,在酒石酸和抗坏血酸的还原作用下,由硝酸银溶液制备了Ag纳米粒子分散液.将两种液体按一定比例混合,再放置过夜后就可制得Ag/MoS2复合纳米材料.以邻氨基苯甲酸甲酯香精分子为标记物,在波长为785 nm的激光激发下,对该复合材料的表面增强拉曼散射(SERS)光谱性能进行了测试,结果表明,该材料对香精分子具有很高的SERS效应.     

PVP辅助水热合成GdF3∶ Eu3+纳米晶及发光性质研究

以聚乙烯吡咯烷酮(PVP)为表面活性剂,采用水热法制备了GdF3∶Eu3+纳米晶.利用X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(IR)和荧光光谱对样品进行了表征.XRD研究结果表明:制备的样品为正交结构的GdF3纳米晶.PVP的使用有利于减小晶粒尺寸和提高颗粒的均匀性.发射光谱研究结果表明:位于594 nm处的主发射峰来自于Eu3+的5 D0→7F1磁偶极跃迁.5D0→7F1与5 D0→7 F2跃迁发射强度比值表明:以PVP为表面活性剂制备的样品中Eu3+的局域对称性相对下降.激发光谱研究结果表明:Gd3+与Eu3+之间有较好的能量传递.纳米晶表面的PVP可能与稀土离子之间形成配位键.     

球磨增强液相剥离法制备h-BN纳米片的工艺研究

针对异丙醇溶液中高质量、高产率六方氮化硼(h-BN)纳米片的制备工艺开发问题,本文在研究h-BN粉在异丙醇(IPA)溶液中分散工艺及其悬浮稳定性的基础上,采用球磨与超声相结合的方法研究其剥离工艺,系统研究超声时间、功率、h-BN浓度及球磨时间对h-BN剥离效果的影响.采用XRD、扫描电镜(SEM)、透射电镜(TEM)、原子力显微镜(AFM)等对h-BN球磨粉体和所制备的h-BN纳米片进行了表征,并用吸光度表征了h-BN剥离产率.研究结果表明:在异丙醇溶液中加入5wt;的油酸(OA)可以提升h-BN粉的悬浮稳定性,从而提升剥离效果和效率;在液相超声剥离时,提高粉体浓度,纳米片层数提高;提高超声功率,可获得少层h-BN纳米片,但纳米片均匀性下降且制备效率较低.将h-BN粉与异丙醇溶液在300r/min转速下球磨10 h后,以0.25 mg/mL的BN/IPA溶液在350 W功率下超声20h,剥离出的h-BN纳米片为10层以下,层间距为0.33 nm,同时使剥离产率提高6.4倍.     

微乳液法制备二氧化硅包覆ZnS:Mn/CdS纳米晶

采用微乳液法制备核壳结构ZnS:Mn/CdS(～4.5nm)纳米晶,为获得水溶性纳米晶,继续向此微乳液添加硅酸乙酯(TEOS),并使用氨水作为催化剂,通过TEOS水解缩聚反应,在ZnS:Mn/CdS粒子表面生长连续的二氧化硅壳层.采用透射电子显微镜(TEM)、X射线衍射(XRD)、红外光谱(IR)、光致发光谱(PL)对其表面形貌、结构和光学特性进行表征.ZnS:Mn /CdS纳米粒子表面被二氧化硅壳层完全包覆,粒径大小约为10nm左右,粒子均匀性好.由于二氧化硅相无定形且透光性良好,二氧化硅包覆ZnS:Mn/CdS纳米晶的光学特性与未包覆的ZnS:Mn/CdS极其相似.     

基于蒙脱石和层状双氢氧化物纳米剥离的层层自组装异构薄膜制备

以乙酸乙酯为剥离介质,采用超声法剥离有机蒙脱石(CTA-MMT)和层状双氢氧化物(MgAl-SDS-LDH),以聚乙烯醇(PVA)为交联剂,采用层层自组装(LBL)的方法制备了蒙脱石-层状双氢氧化物异构薄膜(PVA/MMT/PVA/LDH)n.采用X射线衍射分析(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、原子力显微镜(AFM)和紫外-可见光分光光度计对样品进行了表征.结果表明,超声剥离处理后的CTA-MMT和MgAl-SDS-LDH片层厚度分别达到17 nm和12 nm.(PVA/MMT/PVA/LDH)n异构薄膜层间距为1.81 nm,一个组装循环得到以MMT和LDH纳米片层构成薄膜单循环片层,厚度约为170 nm.薄膜对264 nm左右的光呈现强烈的吸收带,并且吸收强度与薄膜厚度之间呈线性关系,表明薄膜单元层具有良好均一性.     

ZnO/Fe2O3复合结构的制备及光电化学性能研究

采用水热法在FTO导电玻璃上制备出大面积高能面裸露的ZnO纳米片阵列.采用旋涂法在纳米片表面制备Fe2O3纳米颗粒形成ZnO/Fe2O3复合结构.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见光吸收光谱和三电极光电测试系统对复合薄膜的结构组成、形貌、光学性能和光电化学性质进行了表征和分析.研究结果表明,随着Fe2O3复合次数的增加薄膜的光吸收范围逐步拓宽到可见光区,ZnO/Fe2O3复合结构光电极的光电流明显高于单纯的ZnO纳米片阵列光电极.     

95;Ar+5;H2气氛退火对Ag/MoS2和Ag/BN/MoS2薄膜形貌和结构的影响

采用射频(RF)磁控溅射在室温下连续逐层沉积,然后在95;Ar+5;H2混合气氛中进行500 ℃低温退火制备了Ag/MoS2和Ag/BN/MoS2纳米薄膜,采用拉曼光谱(Raman)、X射线光电子能谱(XPS)和原子力显微镜(AFM)对其结构、组成和表面形貌进行了研究.结果表明:所制备的纳米膜均匀连续,界面紧密巨清洁.95;Ar+5;H2混合气氛中退火能强烈影响顶部MoS2层的形貌并有效去除MoS2中的杂质氧改善其结晶性、稳定性和结构完整性;顶部MoS2层在沉积态时呈细小颗粒状,退火后呈片层状和颗粒状混合形态,特别是引入BN 层后促进了其向更大更薄的片状转变,巨MoS2薄膜由块状变成类层状结构.另外,电性能表征显示Ag/MoS2具有良好的欧姆接触巨电阻率低,引入BN层使得Ag与BN以及BN与MoS2的界面处产生肖特基势垒从而使Ag/BN/MoS2具有整流特性.     

纳米晶粒多晶Si薄膜的低压化学气相沉积

利用低压化学气相沉积(LPCVD)方法,以充Ar的SiH4作为反应气体源,在覆盖有热生长SiO2层的p-(100)Si衬底上制备了具有均匀分布的纳米晶粒多晶Si膜(nc-poly-Si).采用扫描电子显微镜(SEM)、原子力显微镜(AFM)和拉曼谱等检测手段,测量和分析了沉积膜层的表面形貌、晶粒尺寸与密度分布等结构特征.结果表明,nc-poly-v膜中Si晶粒的尺寸大小和密度分布强烈依赖于衬底温度、SiH4浓度与反应气压等工艺参数.典型实验条件下生长的Si纳米晶粒形状为半球状,晶粒尺寸约为40nm,密度分布约为4.0×1010cm-2和膜层厚度约为200nm.膜层的沉积机理分析指出,衬底表面上Si原子基团的吸附、迁移、成核与融合等热力学过程支配着nc-poly-Si膜的生长.     

Crystal structures of the cis and trans isomers of a tetrathia[3.3.3.3]cyclophane

Both the cis and trans isomers of 3,11,18,26-tetrathiatricyclo[26.2.2.1^5,9.2^13,16.1^20,24] hexatriaconta-5,7,9,20,22,24-hexene have been prepared and structurally characterized. Each of these centrosymmetric tetrathia dimers includes two cyclohexane rings in chair conformations with either 1,4-cis or 1,4-trans bonding and two meta-substituted benzene rings. The cis isomer packs into the monoclinic space group P2₁/a with a = 10.485(3)Å, b = 10.3956(18)Å, c = 14.1343(10)Å, = 105.200(13)°, Z = 2 and refined to an R factor of 0.046. The trans isomer crystallizes in the monoclinic space group P2₁/c with a = 10.7217(12)Å, b = 5.6797(7)Å, c = 25.415(5)Å, = 96.001(12)°, Z = 2 and refined to an R factor of 0.043. In the cis structure each benzene ring faces a cyclohexane ring while in the trans structure the cyclohexane rings face one another.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

电沉积法制备ZnO纳米棒阵列及其发光特性

本文以掺F的SnO2导电玻璃为基板,以硝酸锌水溶液为电解液,采用三电极恒电位体系电沉积制备ZnO纳米棒阵列,系统考察了硝酸锌浓度和沉积电位等工艺参数对ZnO纳米棒阵列的微观形貌及其发光性能的影响规律.结果表明,硝酸锌浓度和沉积电位对纳米棒阵列的形貌有显著影响,控制适宜的工艺条件可以制备出直径分布均匀、结晶性好且纯度高的六方纤锌矿ZnO纳米棒阵列.荧光光谱分析表明,电沉积制备出的ZnO纳米棒阵列在385 nm附近有一个强荧光发射峰,且发光性能稳定、对纳米棒阵列微观形貌的细微变化不敏感,使其在发光二极管和激光器等领域具有广阔的应用前景.     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P₂S₅ in toluene and have been characterized by elemental analysis, IR, ¹H and ³¹P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻: Monoclinic, P2₁/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?⁻³, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻ comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).     

Phase Properties of Hexanedioldiacrylate/E7 Blends

Abstract

Equilibrium phase diagrams of uncured and UV-cured difunctional hexanedioldiacrylate and the eutectic mixture of low molecular weight liquid crystals E7 are established by polarized optical microscopy and differential scanning calorimetry. Data are analyzed using the Maier-Saupe model of nematic order. In the case of the uncured system the Flory-Huggins free energy of isotropic mixing is applied while for the cured system, the Flory-Rehner elastic free energy model is used. A good correlation between experimental and theoretical phase diagrams is found in both systems.     

C–H...O,C–H...π and π–π stacking interactions in 3-(2,4-dimethylphenyloxymethyl)-3,4-dihydroisocoumarin

3-(2,4-Dimethylphenyloxymethyl)-3,4-dihydroisocoumarin (C₁₈H₁₈O₃) was prepared by the alkylation of o-lithio N-methyl benzamide with 2-(2,4-dimethylphenoxy)methyl oxirane, followed by alkaline hydrolysis. The compound crystallizes in the orthorhombic space group Pbca with unit cell parameters : a = 8.239(2) Å, b = 14.918(5) Å, c = 24.831(9) Å, Z = 8. The crystal structure was solved by direct methods and refined to R = 0.0514 for 1564 observed reflections. The heterocyclic ring adopts a distorted half-chair conformation. Molecules are connected by π–π interactions between phenyl rings of the isocoumarin nucleus forming dimers. Dimers are connected via C–H...O hydrogen bonds forming chains. Further intermolecular C–H...π hydrogen bonds link the dimer chains to form supramolecular structure.     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

The structure of Zn₄Na(OH)₆SO₄Cl·6H₂O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and R_w=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na⁺ ions which occupy the interlayer space.     

A new method for the investigation of orientation relationships in meteoritic plessite

The orientation relationship (OR) between the bcc and fcc phase in the plessite microstructure of the iron meteorites Watson, Agpalilik and Gibeon has been analysed in a scanning electron microscope using electron back‐scattered diffraction (EBSD). A very strong OR exists, independently on the analysed plessite type and the observed spreading of single orientation data. The agreement between the experimental orientation distribution and existing models varies for each meteorite. The black plessite in the Agpalilik corresponds to the Nishiyama‐Wassermann model whereas the duplex plessite of the Gibeon meteorite shows an OR close to the Kurdjumov‐Sachs model. The Watson meteorite is strongly deformed so that a general OR is difficult to determine due to the blurred experimental orientation distribution. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

Abstract  The title compound, C₁₈H₁₈BrN₃O₃S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal] reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these angles which therefore play a role in stabilizing crystal packing. Graphical Abstract  Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C₁₈H₁₈BrN₃O₃S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.