ZnWO4纳米晶光催化剂的制备及表征

以Na2WO4·2H2O和Zn(NO3)2·6H2O为原料,采用水热法制备出ZnWO4纳米晶催化剂.以曙红B为目标降解物,研究了ZnWO4催化剂的光催化性能,探讨了水热温度、水热时间和水热溶液pH值对ZnWO4催化剂的结晶形态及光催化活性的影响规律,结果表明:在酸性条件下制备的ZnWO4为片状结构,链状分布,而在碱性条件下为棒状结构.在180 ℃,24 h的制备条件下,ZnWO4催化剂显示出最高的光催化活性.水热溶液pH=5和pH=8时制得的催化剂在2 h内对5 mg/L的曙红B溶液的脱色率分别达到86;和95;.制备过程中溶液的pH值,催化剂的晶态和比表面积是影响催化剂活性的重要因素.     

钛源对CaTiO3枝晶结构的光催化性能影响

通过改变不同钛源,在无模板或表面活性剂条件下采用溶剂热法制备了CaTiO3枝晶结构.样品用X射线衍射、扫描电子显微镜和比表面积分析仪进行了表征,并用紫外-可见吸收光度计测试样品的光吸收.研究不同钛源种类对CaTiO3样品的微观结构和光降解率的影响.结果表明:钛源为钛酸丁酯所制备的CaTiO3样品呈现发育良好的枝晶结构,其降解罗丹明B溶液的降解率最高.这主要是由于样品的结晶度高、枝晶结构使其具有低的反射率,因此样品呈现出较高的光降解率.     

低温水热法制备高催化效率钒酸铋可见光催化剂

采用低温水热合成法,通过控制反应体系pH值实现了对晶体形貌的调控,制备了高催化效率的单斜相钒酸铋催化剂.对样品进行了X射线衍射、紫外可见漫反射吸收光谱、扫描电镜和比表面积分析,并以罗丹明B的降解考察了样品的光催化活性.结果表明,反应体系pH值影响钒酸铋的形貌和光催化性能,pH值为7条件下制备得到的BiVO4样品对罗丹明B的光催化降解率最大,光催化反应lh对罗丹明B的降解率为93.56;.H2O2作为电子捕获剂,与电子反应形成羟基自由基,抑制电子和空穴对的复合,H2O2协同催化显著提高了光催化效率.     

高催化效率钒酸铋可见光催化剂的制备及性能研究

采用水热合成法,以十二烷基苯磺酸钠(SDBS)作为表面活性剂实现对晶体形貌的调控,制备了高催化效率的棒状单斜相钒酸铋催化剂,通过对罗丹明B的催化降解和样品的测试表征,研究了十二烷基苯磺酸钠加入量对钒酸铋光催化性能和形貌的影响.加入十二烷基苯磺酸钠的质量分数0.08;时,制备得到BiVO4样品对罗丹明B的光催化降解效率达到最大.并对H2O2协同催化提高催化效率的机理进行了探讨.     

不同形貌Sb2O3的控制合成及其光催化性能研究

采用醇解法与水热法制备了Sb2O3光催化材料,研究了制备条件对Sb2O3晶型、形貌及催化性能的影响.结果表明,以PEG-400为表面活性剂、反应体系pH=7时,通过醇解法制得的立方晶型、呈球形颗粒状的Sb2O3催化性能最佳,在紫外光照180 min时,对10.0 mg/L罗丹明B的降解率达到了96.8;;对20.0 mg/L左氧氟沙星降解率为66.3;;对10.0 mg/L磺胺吡啶降解率为46.2;.当反应温度为160℃,反应时间为12 h时,由水热法制得的斜方晶型、呈枕头状的Sb2O3催化性能较差,在紫外光照射180 min时,对10.0 mg/L罗丹明B的降解率为57;.     

三维分级花球结构Bi2WO6的制备及其光催化性能研究

以L-赖氨酸为模板剂,采用水热法成功制备出三维分级花球结构Bi2WO6光催化剂.采用X射线衍射(XRD)、扫描电镜(SEM)等测试方法对所制备样品进行了表征.研究了水热反应过中反应温度、时间及L-赖氨酸添加量等因素对样品形貌的影响,提出三维分级花球结构Bi2 WO6的可能形成机理.此外,以罗丹明B溶液为模拟染料废水,在模拟太阳光照射下考察了样品的光催化活性,结果表明:以L-赖氨酸为模板剂所制备的花球形Bi2WO6 (L-BWO)具有较高的光催化活性,与不添加模板剂情况下所制备的片状Bi2WO6 (BWO)相比,L-BWO光催化剂的降解效率约是BWO的1.5倍.     

pH值对水热合成BiVO4粉体及其光催化性能的影响

以五水硝酸铋和偏钒酸铵为起始原料,在不同前驱液pH值(0.5、5、7、9、11)条件下水热合成制备BiVO4粉体,采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)表征其晶相结构和微观形貌,以罗丹明B(RhB)为目标降解物研究BiVO4粉体紫外光催化性能,研究结果表明:水热合成的BiVO4粉体均为单斜相,且结晶良好,纯度较高;粉体具有四种微观形貌,分别为表面光滑致密的多面体、不规则棒状、细微树枝状、长径比稍小的长方柱状;pH =7合成的细微树枝状BiVO4粉体,紫外光照射30 min RhB降解率达到90;,照射120 min降解率达到98;以上.     

水热法制备铁酸铋及光催化性能研究

以金属硝酸盐、硝酸、氢氧化钠和去离子水为原料,采用水热合成法来制备铁酸铋.研究了水热温度、pH值、水热反应时间对合成反应的影响,并采用X射线衍射、扫描电镜、热重分析仪、振动样品磁强计等手段对制备的铁酸铋纳米粉体的相结构、微观形貌进行了表征.结果表明,水热产物和形貌依赖于水热反应条件,通过水热反应条件的调控,制备出平均粒径在300hm左右的BiFeO3纳米颗粒.最后,以甲基橙为目标降解物,研究了BiFeO3纳米颗粒在可见光下的光催化性能.光催化实验显示制备的铁酸铋纳米颗粒在可见光下具有良好的光催化活性.     

Ag修饰TiO2的制备及其在模拟太阳光下的光催化性能研究

采用溶胶凝胶法制备了不同浓度Ag修饰TiO2以及纯TiO2,采用X射线衍射(XRD)、能谱分析(EDS)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、紫外可见光谱(UV-Vis)、荧光光谱(PL)等测试技术对其进行了系统的表征.结果表明,纯TiO2为锐钛矿/金红石混晶结构,Ag-TiO2为锐钛矿结构,Ag加入细化了TiO2晶粒尺寸,并且抑制了锐钛矿向金红石的转变,Ag元素加入后以单质形式存在.以罗丹明B溶液为目标污染物,研究了样品在模拟太阳光下的光催化性能,实验结果表明,Ag-TiO2的光催化活性较纯TiO2有明显提升,4;Ag-TiO2降解率最高,3 h后对罗丹明B的降解率达到83.3;,比纯TiO2降解率提高了68.6;,其反应速率常数k为0.00896 min-1,为纯TiO2的3.12倍.     

可见光响应(001)晶面纳米TiO2光催化剂的制备及性能研究

以钛酸丁酯为钛源,氢氟酸为形貌控制剂,采用水热法合成了具有高表面能(001)晶面的锐钛矿相TiO2纳米材料.利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及紫外-可见漫反射光谱分析(UV-vis)对样品的形貌、结构和谱学性能进行表征,并以甲基橙溶液为目标污染物,研究其光催化性能和最佳制备条件.结果表明,以氢氟酸为形貌控制剂时,可制备锐钛矿相(001)晶面纳米TiO2纳米材料,能拓宽TiO2体系光响应范围,并具有较高的光催化性能;当反应温度为180.℃、时间为24 h、F/Ti摩尔比为1.5时,样品对甲基橙溶液光催化降解率最高,在紫外光照射条件下1h内降解率可达99.08;,其可见光降解率为66.79;.     

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).     

First-principles coexistence simulations of supercooled liquid silicon

We perform first-principles coexistence simulations of the low-density and the high-density phases of supercooled liquid silicon and find a negative slope for the coexisting line in the temperature-pressure plane. Electron density maps and electron-localization function plots of the two phases of silicon show marked differences. The calculated differences suggest more localized electrons in the low-density liquid compared to the high-density liquid, coming from an increased population of covalent bonds, which further explain the calculated negative slope in the two phase coexistence regime. This is consistent with the presence of a pseudo-gap in low-density liquid silicon, absent in the high-density liquid which shows a metallic behavior.     

Crystal structures of thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane

Structures of both thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane, ?C₆H₄?CH₂SCH₂?C₆H₁₀?CH₂SCH₂?, have been determined, wherecis andtrans refer to the attachments to the cyclohexane ring. Thecis form crystallizes in the monoclinic space groupP2₁/c witha=8.4299(11)Å,b=21.772(2)Å,c=8.9724(13)Å, β=116.574(11)^o, andZ=4. Thetrans isomer packs into the monoclinic space groupP2₁ witha=8.159(16)Å,b=10.185(5)Å,c=9.558(2)Å, β=112.435(18)^o, andZ=2. The cyclohexane ring of thecis isomer is in the chair conformation, while the cyclohexane of thetrans isomer is found in a twisted boat conformation.     

CTAB与SDBS对碳酸锶粒子生长形态调控及机理研究

以表面活性剂CTAB和SDBS为化学添加剂,采用化学共沉淀法对碳酸锶晶体的生长形态进行调控,成功地制备出了实心的树枝状和花瓣为空心的花状碳酸锶粉体,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FT-IR)等分析手段对样品进行了表征;最后重点对化学添加剂可能产生的影响机理进行了初步的探讨.结果表明,CTAB和SDBS在晶体生长的过程中能起到显著的影响作用,两者对粒子分散性能的作用效果相反,而且后者对晶体(013)和(213)晶面表面能降低的贡献明显大于前者.     

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.     

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.     

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.     

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.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P2₁/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure.