Bi4Ti3O12/Ag/AgCl复合纤维的制备及可见光催化性能

本文合成了钛酸铋/银/氯化银(Bi4 Ti3O12/Ag/AgC1,BTO/Ag/AgCl)复合纳米纤维,并研究了其可见光催化性能.通过静电纺丝技术和高温煅烧制备了BTO纳米纤维,采用沉淀-光照还原法在BTO纳米纤维表面负载了Ag/AgC1纳米颗粒获得BTO/Ag/AgC1复合纤维.结果 表明,BTO和Ag/AgC1均具有良好的结晶性能,BTO/Ag/AgC1比单纯的BTO纳米纤维具有更强的可见光吸收.光催化测试表明,由于Ag/AgC1对可见光吸收的增加,以及与BTO间形成的半导体异质结,BTO/Ag/AgC1复合纳米纤维对染料RhB的光催化降解效率均高于纯的BTO纳米纤维,经100 min光照后可由29;提高到80;.     

聚乙烯醇改性磷酸银的光催化活性研究

在制备的磷酸银表面吸附少量的聚乙烯醇(PVA),并通过热处理制备了DPVA/Ag3 PO4复合材料.使用傅立叶红外光谱法(FT-IR)和荧光光谱法(PL)对DPVA/Ag3 PO4复合材料进行表征.分析得知,经聚乙烯醇复合改性的DPVA/Ag3 PO4复合微粒中存在共轭结构,光生电子-空穴对复合率降低,光催化活性得到显著提高.研究了不同条件(复合比例、热处理温度、热处理时间)下制备的复合光催化剂在可见光下催化降解甲基橙的光催化性能.当PVA与Ag3 PO4质量比为1:4000,热处理温度为190℃,热处理1 h时光催化效果最好.     

Ag3PO4/ATP纳米复合材料的制备及可见光催化性能研究

以天然矿物凹凸棒石(简称ATP)为载体,在其表面原位生成纳米Ag3PO4,制备Ag3POJATP复合光催化剂.利用X射线衍射(XRD)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(Uv-vis DRS)等测试方法对复合材料的表面结构、形貌、光响应性能进行了研究.结果表明:Ag3PO4/ATP复合光催化剂中Ag3PO4-以纳米微球均匀分布在ATP表面,平均直径12.5 nm.进一步通过150 W碘钨灯下降解甲基橙(MO)的实验,研究了光催化材料的可见光催化性能.实验结果表明,Ag3PO4、Ag3PO4/ATP在可见光下具有光催化活性,Ag3PO4/ATP的光催化性能优于Ag3PO4,2.5h对甲基橙的降解率达到93.4;.     

ZnSe/ZnS 核壳结构量子点的制备与表征

采用外延生长法在低于 ZnS 晶体成核温度(120 ℃)的条件下,通过在ZnSe 量子点表面生长 ZnS,制备出结晶良好的 ZnSe/ZnS 核壳型量子点.通过 X 射线衍射(XRD),透射电镜分析(TEM)证实了核壳结构的生成.通过荧光光谱和紫外-可见光吸收光谱分析证实,核壳结构的形成改善了 ZnSe 量子点的荧光特性.通过改变反应温度、反应时间、反应物的用量等实验参数,可得到不同厚度ZnS壳层包覆的核壳型量子点.所制备的ZnSe/ZnS量子点具有良好的水溶性,可以分散形成稳定、澄清的水溶液.在紫外灯的照射下,溶液呈现明亮的蓝绿色荧光.     

介孔羟基磷灰石与氨基修饰碳点复合结构的制备及性能研究

通过在一定水热条件下混合介孔羟基磷灰石(Mesoporous hydroxyapatite,MHA)和氨基修饰碳点(N-CDs)得到了MHA/N-CDs复合结构.利用XRD、FHR和HRTEM的表征,证实了N-CDs成功嫁接到MHA表面.N2吸附-脱附和TEM的分析指出,MHA的介孔孔径为5 nm左右,且存在一定量的大孔结构.在可见光下催化降解亚甲基兰结果表明,复合体系的光催化能力大幅提高,约是N-CDs的两倍.     

水溶性CdZnTe量子点荧光猝灭法测定银离子的研究

以疏基丙酸(MPA)为修饰剂,制备了水溶性CdZnTe量子点,研究了pH值,回流时间对CdZnTe量子点荧光强度的影响.基于Ag离子对CdZnTe量子点的淬灭作用,建立了一种新的测定Ag离子的方法.在最优试验条件下,Ag离子浓度在2×10-7～2×10-6 mol/L时与CdZnTe量子点荧光强度呈线性关系,线性回归方程为△F ＝-7 ×10-5c+5×10-5,相关系数R＝0.9787.该量子点荧光分析方法简便快速、灵敏度高、选择性好.     

Ag3 PO4量子点修饰Ag3 PO4/Bi2 WO6异质光催化剂的构筑及其可见响应活性增强机制

采用水热法制备了三维分级球形结构的Bi2 WO6,在此基础上采用沉淀-沉积法将Ag3 PO4量子点(QDs)沉积在Bi2 WO6的表面,成功获得Ag3 PO4/Bi2 WO6异质复合材料光催化剂.借助XRD、FE-SEM、TEM、UV-Vis-DRS等技术对所得Ag3 PO4/Bi2 WO6异质复合材料光吸收性能、形貌和组成进行了系统表征,并以次甲基蓝(MB)和苯酚(Ph)的光催化降解为探针反应,探讨了Ag3 PO4 QDs表面沉积对Bi2 WO6光催化性能的影响.结果表明,尺寸约为10 nm左右的Ag3 PO4 QDs均匀的沉积在Bi2 WO6的表面,二者形成新颖的Ag3 PO4/Bi2 WO6异质结构.活性实验结果表明,与纯Bi2 WO6相比异质催化剂的活性显著增强,当Ag3 PO4与Bi2 WO6复合比为1:1时催化活性最高,其降解Ph的表观速率常数(kapp/min-1)约为纯Bi2 WO6的7倍.     

1.3微米发光自组织InAs/GaAs量子点的电致发光研究

用优化的MBE参数生长了1.3μm发光的InAs/GaAs量子点材料,并制成发光二极管,对不同温度和有源区长度下样品的电致发光谱进行了细致的研究.观察到两个明显的电致发光峰,分别对应于量子点基态和激发态的辐射复合发光.实验表明,由于能态填充效应的影响,适当增大量子点发光器件有源区长度,更有利于获得基态的光发射.这个结果提供了一种控制和调节InAs/GaAs量子点发光二极管和激光器的工作波长的方法.     

Ag3PO4/ZnO复合粉体制备及其可见光催化性能

室温下,以ZnO粉体、Na2HPO4、AgNO3和聚乙烯吡咯烷酮为原料,成功制备出了系列Ag3PO4/ZnO复合粉体.采用X射线衍射仪、扫描电子显微镜和紫外-可见光谱仪分别对复合粉体的物相、形貌和可见光吸收性能进行了表征.研究了不同摩尔比的Ag3PO4/ZnO复合粉体的光催化性能.结果表明:当ZnO和Ag3PO4摩尔比约为1:1时,所得的Ag3PO4/ZnO复合粉体对罗丹明B染料的可见光催化效果最好,降解率达到99;.     

葡萄糖胺稳定CdS量子点的绿色合成及光谱特性

以葡萄糖胺(Glucosamine,GIcN)为稳定剂,以Cd(Ac)2 ·2H2O和Na2S ·9H2O作为反应剂,在室温下水相合成了CdS量子点.通过X射线衍射(XRD)、透射电镜(TEM)、紫外-可见吸收光谱(UV -Vis)和荧光发射光谱(PL)对样品的结构、形貌和光学性能进行了表征,考察了反应体系的pH值、GlcN/Cd的物质的量比对量子点光谱性能的影响.结果表明,所获得的CdS量子点为立方闪锌矿结构,且尺寸分布均一,结晶度高,具有丰富的表面缺陷和量子尺寸限域效应.同时,对CdS量子点形成的可能机理进行了初步的探讨.     

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.