溶剂热合成单分散硫化镉纳米晶

在双表面活性剂十八胺和油酸存在条件下, 以氯化镉和硫粉作为反应前驱物, 通过简单的溶剂热方法合成单分散性闪锌矿硫化镉纳米晶, 粒径大小在13 nm. 用X射线衍射(XRD)、透射电子显微镜(TEM)对产物的结构和形貌进行了表征, 同时对硫化镉纳米晶的紫外吸收谱和光致发光谱(PL)性能进行了表征. 实验结果表明合成的样品具有很好的发光性能, 此外溶剂热反应的温度对纳米晶的单分散性有重要影响. 并对硫化镉纳米晶的形成机理做了初步的研究.     

CdS纳米棒的制备、表征及其形成机理

以三辛基膦(TOP)为单一配位溶剂,二水合乙酸镉和硫粉为前驱体,用高温热解的方法制备CdS纳米棒.通过X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)、紫外-可见(UV-Vis)分光光度计、荧光(PL)光谱、傅里叶变换红外(FTIR)光谱和核磁共振磷谱(31PNMR)等方法对样品的结构、形貌和光学特性进行了表征.考察了前驱体Cd/S摩尔比和反应物浓度对硫化镉纳米结构的影响.实验结果表明,该法制备的CdS纳米棒为纤锌矿结构,直径为4.0nm,长度为28.0nm,沿[001]方向择优生长,具有量子限域效应.同时,对CdS纳米晶的形成机理进行了初步的探讨.     

CdS/SiO2纳米复合材料的合成及光学性能

以合成的丙氨酸镉为纳米粒子的前驱体,在不加酸或碱性催化剂的条件下,利用丙氨酸镉分子中的胺基催化硅氧烷水解缩合生成二氧化硅,同时将丙氨酸镉均匀地引入到二氧化硅的内部,通过硫化原位生成硫化镉纳米颗粒,制得硫化镉/二氧化硅(CdS/SiO2)纳米复合材料.用傅里叶变换红外光谱、核磁共振氢谱、紫外-可见光谱、荧光显微镜和透射电子显微镜等方法对CdS/SiO2复合材料进行表征,结果表明,硫化镉粒子均匀分布在二氧化硅内部,使其具有良好的荧光特性.     

壳聚糖修饰的Pt纳米粒子

以氯铂酸为前驱体,硼氢化钠为还原剂,壳聚糖为保护剂,通过化学还原法,在室温条件下制备了Pt纳米粒子.透射电镜(TEM)显示纳米粒子的粒径在28.5nm左右,X-射线衍射(XRD)表明纳米粒子的晶型为面心立方结构,X-光电子能谱(XPS)和红外(FTIR)证实了壳聚糖包覆在纳米粒子表面,热重分析(TGA)表明纳米粒子表面的壳聚糖含量大约为52.8％.     

闪锌矿结构CdS纳米晶的制备

以3-巯基丙酸为硫源, 采用水热法制备了尺寸小于10 nm、具有强光致荧光的闪锌矿型立方CdS半导体纳米晶. 用EDS能谱、透射电镜(TEM)、高分辨透射电镜(HRTEM)和XRD对晶体的化学成分、大小及结构进行了表征, 并分析了影响纳米晶尺寸的因素, 研究了闪锌矿型硫化镉纳米晶的荧光激发与发射谱.     

CoFeOx/MoO2准平行纳米阵列电极的析氢性能

利用CoFe层状双金属氢氧化物(CoFe LDH)准平行纳米片阵列作为载体前驱体,通过原位负载及煅烧方式,实现了含有氧空位的MoO₂纳米颗粒在纳米片阵列表面的生长。电化学研究结果表明,所得CoFeO_x/MoO₂纳米阵列电极具有高析氢反应(HER)催化活性。该电极在10和1 000 mA·cm^-2时的HER过电位分别为40和217 mV。在50 mA·cm^-2的电流密度下,该电极可以稳定运行125 h。     

氧化锌纳米棒/云母复合粉体的合成、表征及红外发射性能

采用液相沉积法制备了氧化锌(ZnO)纳米棒负载云母复合粉体,其合成工艺分为:(1)云母粉体表面沉积ZnO纳米粒子,并经煅烧制得表面晶种化的云母粉体;(2)以七水硫酸锌(ZnSO4·7H2O)为前驱体,乙醇胺和氨水为络合剂,制得液相沉积前驱体溶液,并在晶种化的云母粉体表面沉积ZnO纳米棒。利用X-射线衍射(XRD)、ζ电位仪、扫描电子显微镜(SEM)以及红外发射率测试仪对氧化锌/云母复合粉体进行了测试与表征。结果表明,云母分散于乙醇水体积比为1∶1的混合溶液中,其表面带负电(-37 mV),而ZnO粒子表面则带正电(16 mV);两种粒子混合时,可通过静电引力实现ZnO纳米粒子在云母表面沉积;随着云母表面ZnO纳米棒沉积密度的增大,复合粉体在8~14μm波段内的红外发射率逐渐增大,从0.800增加至0.863;对比棒状ZnO球体,结构单元聚集状态的变化对最终红外发射性能的影响不大。     

熔盐分解制备氧化锌纳米晶

以新制的乙酰丙酮合锌为前驱体,添加NaCl助剂,在650℃熔盐分解制得了六棱柱形结构的ZnO纳米晶.用X-射线衍射分析(XRD)、能量色散X射线分析(EDX)和场发射扫描电子显微镜(FFSEM)对粉体进行了表征.结果表明,ZnO为六棱柱形纳米晶,属六方纤锌矿结构,结晶性好,平均长度约90nm,平均直径约60nm,长径比约为1.5:1.通过与不添加NaCl的对比试验,简单探讨了六棱柱形ZnO纳米晶的生长过程.     

结晶二氧化钛多孔球的常压液相制备

利用沸水处理有机钛前驱体球较为便捷地制备出结晶二氧化钛多孔球,采用XRD、SEM和TEM对二氧化钛球进行表征,并探讨了二氧化钛球锐钛矿纳米晶形成以及形貌变化的机理。结果表明：延长沸水处理时间有利于多孔结构的形成和纳米粒子的晶化,随处理时间的增加,前驱体球表面变得越来越粗糙,二氧化钛结晶度也逐渐增强。其形成机理主要归因于沸水处理过程中有机钛前驱体球原位发生的完全水解和聚合。     

以单晶银纳米方块为液相外延生长晶种的纳米晶形貌可控合成方法

本文简要综述了以单晶银纳米方块做为可控外延生长的品种来合成各种银纳米晶的相关工作．通过改变银前驱体和晶种颗粒的比例、表面包裹分子及其用量、还原剂浓度、添加欠电位金属阳离子等手段,我们成功地控制了银纳米晶的外延生长方向和裸露晶面,并合成出一系列尺寸、形貌可控的银纳米晶,包括立方体、立方八面体、八面体、八足体、二十四面体、凹面立方八面体和凹面八面体等．除了对合成方法和过程的介绍,本文还简要讨论了每种纳米结构的形成机制．     

Controlled growth and photocatalytic properties of CdS nanocrystals implanted in layered metal hydroxide matrixes

Layered double hydroxide Cd(1)(-)(x)()Al(x)()(OH)(2)(DS)(x)().3.0H(2)O (CdAlDS) and a related hydroxide salt compound Cd(2)(OH)(3)(DS).2.5H(2)O (CdDS), where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic layers, have been synthesized and used as precursors for CdS nanoparticle growth. Through a gas/solid reaction, CdS nanocrystals implanted in the layer matrixes of the layered double hydroxides are grown, and the sizes of the nanocrystals vary in the range of 3-6 nm in diameter. The presence of trivalent Al cations in the layered double hydroxide can be taken advantage of to control the size of the CdS nanocrystals, and it also helps to prevent the formed nanocrystals from extraction from the solid matrixes. The nano-CdS implanted composite exhibits high photocatalytic activity for degradation of the nonbiodegradable rhodamine B under both UV and visible irradiations.     

The N-alkyldithiocarbamato complexes [M(S2CNHR)2] (M=Cd(II) Zn(II); R=C2H5, C4H9, C6H13, C12H25); their synthesis, thermal decomposition and use to prepare of nanoparticles and nanorods of CdS

A series of N-alkyldithiocarbamato complexes [M(S2CNHR)2] (M=Cd(II), Zn(II); R=C2H5, C4H9, C6H13, C12H25) have been synthesised and characterized. The decomposition of these complexes to sulfates has been investigated, and a mechanism proposed. The structures of [Zn(S2CNHHex)2], [Cd(SO4)2(NC5H5)4)]n and [Cd(SO4)2(NC5H5)2(H2O)2)]n have been determined by X-ray single crystal method. The cadmium complex [Cd(S2CNHC12H25)2] and zinc complex [Zn(S2CNHC6H13)2] were used as single-source precursors to synthesize CdS and ZnS nanoparticles, respectively. The synthesis of CdS nanoparticles was carried under various thermolysis conditions and changes in the shape of derived nanoparticles were studied by transmission electron microscope (TEM).     

Water-soluble CdSe and CdSe/CdS nanocrystals: a greener synthetic route

We report a new green synthetic route of CdSe and core-shell CdSe/CdS nanoparticles (NPs) in aqueous solutions. This route is performed under water-bath temperature, using Se powder as a selenium source to prepare CdSe NPs, and H(2)S generated by the reaction of Na(2)SH(2)SO(4) as a sulfur source to synthesize core-shell CdSe/CdS NPs at 25-35 degrees C. The synthesis time of every step is only 20 min. After illumination with ambient natural light, photoluminescence (PL) intensities of CdSe NPs enhanced up to 100 times. The core-shell CdSe/CdS NPs have stronger photoactive luminescence with quantum yields over 20%. The obtained CdSe NPs exhibit a favorable narrow PL band (FWHM: 50-37 nm) with increasing molar ratio of Cd/Se from 4:1 to 10:1 at pH 9.1 in the crude solution, whereas PL band of corresponding CdSe/CdS NPs is slightly narrower. The emission maxima of nanocrystals can be tuned in a wider range from 492 to 592 nm in water by changing synthesis temperature of CdSe core than those reported previously. The resulting new route is of particular interest as it uses readily-available reagents and simple equipment to synthesize high-quality water-soluble CdSe and CdSe/CdS nanocrystals.     

Synthesis of nanocrystal-polymer transparent hybrids via polyurethane matrix grafted onto functionalized CdS nanocrystals

We reported the first synthesis of CdS nanocrystal-polymer transparent hybrids by using polyurethane (PU) grafted onto quantum dots (QDs) CdS nanocrystals. In a typical run, the appropriate amounts of cadmium chloride (CdCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H2O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus's model according to UV-vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystals is about 5 nm. Then, PU-CdS transparent nanocomposites hybrids were synthesized by a two-step reaction. The effect of the different ratios of ME/Cd2+ and H2O/DMF on the resulting particle size of CdS nanocrystals was investigated by UV-vis absorption measurements. FT-IR and TGA characterizations indicate the formation of robust bonding between CdS nanocrystals and the organic ligand. The fluorescence measurement shows that CdS-PU hybrids exhibit good optical properties.     

A new two-phase route to high-quality CdS nanocrystals

A new two-phase route has been developed to synthesize high-quality CdS nanocrystals with a narrow size distribution and a high photoluminescence (PL) quantum yield (QY). In the two-phase system, toluene and water were used as separate solvents for cadmium myristate (CdM2) and thiourea, which served as cadmium source and sulfur source, respectively, and oleic acid (OA) was used as a ligand for stabilizing the nanocrystals. The reactions were completed in the heated autoclaves. The initial Cd/S molar ratio of the precursors and the reaction temperature were found to be factors that affected the growth of nanocrystals. Furthermore, a seeding-growth technique was developed to synthesize CdS nanocrystals of different sizes, which exhibit PL peaks with quite similar full width at half-maximum (FWHM) values compared to those of the initial nanocrystal seeds in all cases.     

Hydrothermal synthesis, structure, and luminescent properties of selected Zn(II)/Cd(II) coordination polymers constructed from 3,5-bis(x-pyridyl)-1,2,4-triazole (x = 3, 4)

Utilizing 3,5-bis(x-pyridyl)-1,2,4-triazole (x-Hpytz, x = 3; x = 4) as multidentate ligands, six novel coordination polymers with Zn(II) or Cd(II) metal ions were prepared: [Zn(3-pytz)(0.5)(OH)(0.5)Cl](n) (1, 1D ladder), {[Zn(3-Hpytz)(H(2)O)(4)] [Zn(3-Hpytz)(H(2)O)(3)·SO(4)]SO(4)·5H(2)O}(n) (2·5H(2)O, 1D chain), [Cd(3-Hpytz)(SO(4))](n) (3, 3D framework), {[Cd(3-Hyptz)SO(4)·3H(2)O]·2H(2)O}(n) (4·2H(2)O, 1D chain), [Zn(4-pytz)Cl](n) (5, 3D framework) and [Zn(2)(4-pytz)(SO(4))(OH)](n) (6, 3D framework). All compounds were obtained from hydrothermal reactions, with the exception of compound 4 which was obtained by solvent diffusion at room temperature. All compounds were characterized by FTIR, elemental analysis and TGA analysis and their structures were determined by X-ray diffraction. All compounds exhibited substantial thermal stability and showed photofluorescent properties that resulted from ligand π-π* transition.     

Dendronized Cellulose Nanocrystals as Templates for Preparation of ZnS and CdS Quantum Dots

Cellulose nanocrystals (CNC) isolated from bleached bagasse pulp were modified with a second-generation isocyanate dendron (G2-dendron) to prepare dendronized cellulose nanocrystals (DCN). Transmission electron microscopy (TEM), elemental analysis for nitrogen, Fourier transform infrared (FTIR) and ¹³C magic angle spinning nuclear magnetic resonance (¹³C MAS NMR) proved occurrence of the modification of cellulose nanocrystals surfaces. The dendronized cellulose nanocrystals were used as templates for formation of ZnS and CdS quantum dots with uniform diameter at low temperature in water. The prepared DCN/QDs were highly soluble in water. TEM images showed that the size of the prepared quantum dots was about 5 nm in diameter. UV-Visible and fluorescence spectroscopy showed absorption and emission at wavelength values lower than that reported for bulk ZnS and CdS.     

Solvothermal synthesis and luminescence properties of CdS:Mn nanorods

CdS:Mn nanorods have been produced via a solvothermal approach in the nonaqueous solvent of ethylenediamine. An absolutely dominant single Mn²⁺ emission originating from the d-d (⁴T₁-⁶A₁) transition was obtained in CdS:Mn nanocrystals at room temperature. The effects of varying reaction temperature, molar ratio of S/Cd, and reaction time on the crystallinity and luminescence of CdS:Mn nanocrystals were systematically investigated. 1% Mn²⁺-doped CdS nanorods without any other additives were synthesized at 130°C for 10 h with an S/Cd molar ratio of 2:1. They show a rod-like shape, and their luminescence intensity around 593 nm is almost the strongest of all the nanorod samples investigated. CdS:Mn nanorods promise potential applications in nanoscale electronic and photonic devices.     

355 nm光诱发的水体中HNO2与C6H5Br交叉反应机理

利用激光闪光光解技术研究了有氧、无氧条件下HNO2-C6H5Br-H2O体系的光化学反应. 研究结果表明, HNO2与C6H5Br的光化学反应由HNO2光解产生·OH自由基引发, ·OH与C6H5Br反应生成C6H5Br…OH, 反应速率常数为(8.1±0.7)×109 L·mol-1·s-1. C6H5Br…OH可被HNO2或O2氧化. C6H5Br…OH 与HNO2的二级反应速率常数为(3.0±0.5)×107 L·mol-1·s-1, 比C6H5Br…OH与O2的反应速率常数(4.0±0.6)×108 L·mol-1·s-1小, C6H5Br…OH与O2生成的C6H5Br…OHO2以(2.4±0.1)×104 s-1 的速率单分子衰减. 气相色谱-质谱联用(GC-MS)分析表明, C6H5Br…OH 与HNO2或O2作用可形成多种含硝基的化合物或醌类物质.     

十二烷基磺酸钠微乳状液结构转变的电化学研究

制备了C12H25SO3Na-C4H9OH-C7H16-H2O四组分体系在km=W(C4H9OH)/W(C12H25SO3Na)=2时的拟三元相图。使用二茂铁和铁氰化钾作为电化学探针用循环伏安法测定了起始含油量为21％的无水混合物在滴加水过程中所形成的微太液的扩散系数。从扩散系数随含水量的变化确定微乳液的结构转变。含水量为20％－45％时生成油包水型微液;含水量大于65％时生成水包油型微乳液。当含水量在45％－65％之间时形成的是二连续型微乳液。电导率数据证实了循环伏安法的测定结果。