三种改性方法对纳米ZnO催化剂粉体的光催化性能的影响

以SnCl4·5H2O、ZnNO3·6H2O、HCl、NaOH、FeCl3·6H2O为原料,采用共沉淀法制备Fe掺杂纳米ZnO、纳米ZnO/SnO2和Fe掺杂纳米ZnO/SnO2三种复合催化剂粉体,以降解甲基橙溶液反应为模型,研究了不同比例的ZnO/SnO2复合、Fe元素掺杂量以及SnO2复合Fe元素掺杂同时作用对纳米ZnO粉体光催化活性的影响,采用X射线衍射(XRD)测试方法对不同量Fe元素掺杂纳米ZnO粉体进行了表征.采用透射电镜对三种改性方法ZnO粉体进行表征.结果表明:随着ZnO/SnO2的物质的量比增加,ZnO/SnO2复合光催化剂的催化活性先增加,然后降低;随着Fe掺杂量的增加,纳米ZnO粉体的光催化活性先增加,然后降低.三种改性方法都能提高纳米ZnO粉体的光催化活性,其中Fe元素掺杂以及SnO2复合改性纳米ZnO粉体的光催化效果最好,物相为ZnO和SnO2,颗粒尺寸为15 ～20 nm,分散性好,比表面积为68.7m2/g.     

In和过渡金属离子共掺杂对ZnO晶体形貌的影响

采用水热法,KOH作矿化剂,在ZnO前驱物中添加适量的CoCl2·6H2O,FeCl2·4 H2O,NiCl2·6H2O,In2O3,其中Co:In:Zn,Fe:In:Zn,Ni:In:Zn 分别为5:1:100,5:1:100,3:1:100.3 mol/L KOH作矿化剂,温度430 ℃,填充度35;,反应24 h,制备了In和过渡族金属离子共掺的ZnO晶体.结果表明,掺杂In2O3时,所合成的过渡族金属离子掺杂的ZnO晶体均呈现六角片状晶体,晶体形貌规则,表面光滑,直径为5～10 μm.和未掺杂In的晶体相比,掺杂In后,晶体c轴极性生长速度得到明显的控制,a、b轴方向生长速度提高,大面积显露+c{0001}、负极面-c{0001}面,另外还显露正锥面+p{1011}、负锥面-p{101-1-}.     

水热法合成Zn1-xMnxO：Sn和Zn1-x-yMnxCoyO：Cu晶体的磁性

本文采用水热法,以ZnO为前驱物,添加适量的MnCl2·4H2O、SnCl2·2H2O和MnCl2·4H2O、CoCl2·6H2O、CuCl2·2H2O,3 mol/L KOH作矿化剂,430℃反应24 h,分别合成了Zn1-xMnxO:Sn晶体和Zn1-x-yMnxCoyO:Cu晶体.用扫描电镜(SEM)对合成物形貌进行分析,结果表明,Zn1-MnxO:Sn晶体为六棱柱状晶体,直径约为10 μm,较大面积显露正极面c{0001},同时也显露负极面-c{0001}、正锥面p{1011}、负锥面-p{1011}和柱面m{1010}.Zn1-x-yMnxCoyO:Cu晶体也显露负极面-c{0001}、正锥面p{1011}、负锥面-p{1011}和柱面m{1010},{0001}显露面小于{0001}.X射线能谱(EDS)分析表明晶体主要成分为ZnO,Mn2 、Co2 离子掺杂量超过2%;SQUID磁性测量显示所合成晶体在25 K具有反铁磁特征,高温为顺磁性.     

Ce掺杂ZnO纳米晶的光催化性能研究

以Zn( NO3)3·6H2O、Ce( NO3)3·6H2O为原料,明胶为模板分散剂,采用凝胶模板燃烧法制备纯ZnO和Ce/ZnO纳米晶,利用XRD、TEM、BET、UV-Vis漫反射进行表征.以染料罗丹明B为目标降解物考察了样品的光催化活性.结果表明:产物粒子形状基本为球形,结晶良好,属六方晶系结构.相比纯ZnO,Ce/ZnO对光具有更高的吸收利用率,在紫外和可见光下对罗丹明B的降解能力均有明显提高;随Ce掺杂量的增加,样品的粒径减小,比表面积增大,罗丹明B的降解率相应增大,在紫外和可见光下降解率分别可达98.6;、78.3;,其原因在于Ce掺杂有利于在ZnO纳米粒子中心和表面之间产生电势差,实现光生电子-空穴对的有效分离.     

稀土金属Ce3+掺杂ZnO材料的光催化机理

通过溶胶凝胶法制备了光催化活性更高的Ce∶ZnO复合粉体光催化材料,并采用X射线衍射(XRD)、电子顺磁共振(EPR)、紫外可见光谱(UV-Vis)技术对所制备的粉体样品的晶体种类及结构、自由基种类及含量、光催化效率进行表征分析。复合样品的X射线衍射测试结果显示,随着掺杂浓度的增加,先后检测到CeO₂的(111)和(200)晶面特征峰,且衍射峰强度逐渐增强。此外,适量的掺杂(c(Ce³⁺)=2%)可减小ZnO晶体的晶粒尺寸。电子顺磁共振测试结果显示,Ce∶ZnO复合光催化材料中存在三类自由基,分别是Zn-H络合物、正一价氧空位、CeO₂表面吸附的超氧根离子。紫外可见光谱测试表明,适量的掺杂可有效提高ZnO催化剂的光催化活性,综合分析显示,ZnO光催化活性提高的主要原因是Ce³⁺的掺入使得材料中电子数量增多,进而提高了活性自由基·O^-₂的数量。本文通过EPR技术和XRD衍射技术,成功表征了Ce³⁺掺杂对ZnO材料中自由基种类合成的影响过程,并结合UV-Vis技术,对Ce∶ZnO复合材料光催化降解甲基橙的过程中的电子转移过程作出了合理的解释。     

水热合成Cu-Bi2WO6及其光催化性能研究

以Bi(NO3)3·5H2O和Na2WO4·2H2O为原料,NaOH为矿化剂,CuCl2和CuSO4为铜源水热法离子掺杂合成Bi2WO6粉体,并使用XRD、SEM、UV-VIS、XPS对其进行表征,分析了不同铜源离子掺杂Bi2WO6以及掺杂量对所制备样品光催化性能的影响.结果表明,以CuCl2为铜源离子掺杂Bi2WO6的样品粒径减小,吸收边红移.掺杂后的铜以中Cu2和Cu+两种电子形式存在.光催化测试结果表明,以CuCl2为铜源且掺入量为1.5mol;时所制备的Bi2WO6样品的光催化活性最高.     

In掺杂对水热法合成ZnO晶体形貌的影响

本文采用水热法,在ZnO中添加In2O3为前驱物,3mol/L KOH作矿化剂,温度430℃,填充度35;,反应24h,制备了掺In的ZnO晶体.未掺杂In2O3合成的纯ZnO晶体呈六棱锥状,显露负极面-c{0001}、六棱锥面+p{1011}和-p{1011},一般不显露{0001}面.前驱物中掺杂In2O3所合成的ZnO晶体呈六角片状,直径约为5～20 μm,大面积显露{0001}面,另外还显露正锥面+p{1011}、负锥面-p{1011}和负极面-c{0001}.由此可见In掺杂可以明显的改变晶体的形态,使c轴极性快速生长趋向得到明显改善,有利于降低晶体生长缺陷.当采用ZnO晶片为籽晶时,通过水热反应在晶片上生长了一层掺In的ZnO薄膜,通过Hall参数测量得到晶体膜层的电子迁移率约为22cm2/(V·s),载流子浓度约为2×1020 cm-3,具有良好的导电性,同时也说明In可以微量掺入氧化锌晶体.     

纳米Bi2MoO6的水热法制备及光催化性能研究

为进一步提升钼酸铋的可见光催化活性,以Bi(NO3)3·5H2O和Na2 MoO4·2H2O为原料,加入不同表面活性剂辅助水热法制备了纳米级钼酸铋.研究了表面活性剂种类对Bi2 MoO6形貌结构的影响,采用XRD、SEM和FTIR对产物进行了表征.结果表明:在水热合成条件下引入CTAB作为表面活性剂时,合成的纳米片厚度仅为10～20 nm.这种钼酸铋纳米片比普通钼酸铋纳米粉体具有更优的光催化活性,可见光照射180 rmin后对目标污染物亚甲基蓝的降解率可达81;,可见光催化效率提升2～4倍.     

溶液燃烧法合成ZnxCo1-xAl2O4尖晶石型超细陶瓷色料

以Zn(NO3)2·6H2O、Co(NO3)2·6H2O、Al(NO3)3·9H2O和C12H22O11为原料,采用溶液燃烧法合成ZnxCo1-xAl2O4(0≤x≤1)尖晶石型陶瓷色料.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和色度分析仪等检测方法对Zn2+的掺杂量和热处理温度对合成粉体的物相组成、微观形貌和呈色性能的影响规律进行了表征.结果表明:在Zn2掺杂量x=0.2、前驱体溶液中(Zn2++Co2+)浓度为0.3 mol/L、点燃温度400℃、后续热处理温度1200℃和保温时间30 min条件下,合成色料的蓝度值(-b*)达47.03的最大值,其平均晶粒尺寸为120 nm.     

磁性Fe3O4六方片状晶体和单晶纳米棒的水热合成

本文分别以FeSO4·7H2O、(NH4)2Fe(SO4)2·6H2O和NaOH、NH3·H2O为原料,以KClO4与KNO3为氧化剂,采用水热合成法分别合成出Fe3O4六角片状晶体和单晶纳米棒.产物分别用X射线衍射仪(XRD)谱图、透射电子显微镜(TEM)、选区电子衍射(SAED)谱图以及磁滞回线图谱加以表征.结果表明,反应物原料及氧化剂的选择对Fe3O4单晶的制备及其形态的影响至关重要.反应温度控制在110℃,时间为14h.室温下,Fe3O4六方片状晶体和单晶纳米棒的磁化率(Ms)和矫顽力(Hc)均有所区别.     

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 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.     

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.     

Synthesis of spinacine and spinacine derivatives: crystal and molecular structures of Nπ-hydroxymethyl spinacine and Nα-methyl spinaceamine

The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, N^π-hydroxymethyl-spinacine, and a spinacine derivative, N^α-methyl-spinaceamine, have been investigated through X-ray diffraction: Spi(πMeOH)·H₂O, monoclinicP2 _i,a=8.571(1),b=6.682(1),c=8.588(1) Å, and β=94.67(1)^o. Spm(αMe)·2HCl·H₂O, triclinicP l,a=7.492(4),b=10.799(3),c=7.040(2) Å, α=91.88(2), β=98.36(3) and γ=73.34(3)^o. Spi(πMeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) Å between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O?H???O, O?H???N, N?H???N intermolecular hydrogen bonds and C?H???O close contacts. The biprotonated compounds Spm(αMe) crystallizes with two Cl^? anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C?N. The crystal is built up by clusters formed by two biprotonated Spm(αMe) molecules, four Cl^? anions and two water molecules linked together by hydrogen bonds.