CdSe/SiO_2荧光微球的制备及其荧光性能(英文)

利用Stber法制备了CdSe/SiO2荧光微球。用透射电子显微镜,共聚焦显微镜和X射线衍射测试荧光微球的形貌和晶体结构;用荧光光谱表征荧光微球的荧光性能;用动态-静态激光散射仪表征荧光微球的尺寸分布。结果表明:CdSe量子点被包裹在SiO2微球内,并形成了具有良好荧光性能的CdSe/SiO2荧光微球,其荧光性能与合成工艺条件有着显著的相关性。     

CdSe/CdS-PVP纳米复合材料的制备及其光学性能研究

量子点由于高表面能而易于团聚,影响其使用价值。通常需要对量子点进行表面修饰,以提高材料的光电稳定性。首先通过化学键合法在水溶性CdSe/CdS量子点表面引入4,4-偶氮双(4-氰基戊酸)(ACVA),制备一种新型量子点引发剂CdSe/CdS-azo,然后引发单体N-乙烯基吡咯烷酮(NVP)聚合,成功制备出一种新型水溶性纳米复合材料CdSe/CdS-PVP。光学测试结果表明CdSe/CdS-PVP在多种溶剂中具有稳定而优异的发光性能。因此,该水溶性纳米复合材料CdSe/CdS-PVP有望作为生物荧光探针和示踪材料。     

Pickering乳液聚合法CdS/PS荧光复合微球的制备与表征

通过水相合成法制备水溶性硫化镉(CdS)纳米晶,以CdS纳米晶固体粒子为乳化剂,进行Pickering乳液聚合制得CdS/PS荧光复合微球。通过SEM、XRD、FTIR、UV-vis、PL对CdS/PS荧光复合微球的微观结构、结晶情况及光学性能进行了分析和表征。结果表明,该复合微球具有以PS为核、CdS纳米晶为壳的核壳结构;复合微球的平均粒径为450nm;在复合微球中,CdS纳米晶仍然保持其量子尺寸效应,复合微球表现出了较好的荧光性能。     

新型磁性荧光功能纳米复合物的制备及表征

在水相中,采用化学共沉淀法以FeCl_3·6H_2O和FeSO_4·7H_2O为原料合成了超顺磁性Fe3O4纳米粒子,并以甘氨酸、甲基丙烯酸甲酯进行修饰。CdSe/CdS量子点以巯基乙酸为稳定剂制得。最后以乙二胺为联接剂成功制得磁性荧光双功能纳米微球。并利用荧光显微镜、荧光分光光度计、红外、透射电子显微镜(TEM)和振动样品磁强计(VSM)对该微粒进行表征。结果表明,该微粒分散性好,磁性强度高,荧光性能优异。再将其与牛血清白蛋白(BSA)一起培育,表明其生物相容性良好。磁性荧光双功能纳米材料有望在靶向治疗、免疫检测、细胞分离和催化等领域得到广泛应用。     

CdSe与CdSe/ZnS核壳型量子点的制备方法与展望

CdSe及CdSe/ZnS量子点具有特殊的发光性质性质,它们在生物荧光探针、生物芯片、激光器、光电子器件和光催化等领域具有广泛的应用,现在越来越多的研究者更加关注它们在生命科学研究中起到得定性和定量标识生物分子和细胞作用。本文对几种制备CdSe及CdSe/ZnS量子点的方法进行了简单的综述,分别介绍了CdSe的水相、有机相以及绿色合成法,CdSe/ZnS量子点的热注入有机金属法和水相合成法,对这几种方法的优缺点进行了概述,并对其前景做了展望。     

巯基乙酸稳定的CdSe/ZnS核壳结构量子点的制备与表征

用非均相成核原理,在水溶液中制备CdSe/ZnS核壳结构量子点,并研究合成工艺,包括前驱物的滴加方式和用量、CdSe核的水浴反应时间、CdSe与ZnS的摩尔比等因素对CdSe/ZnS核壳结构量子点荧光性能的影响.用透射电子显微镜和x射线衍射仪测试核壳结构量子点的形貌和结构.用紫外吸收光谱与荧光光谱表征CdSe/ZnS核壳结构量子点的荧光性能.结果表明:ZnS壳层在CdSe核量子点表面外延生长,形成了核壳结构;CdSe/ZnS核壳结构量子点的荧光性能明显高于单一的CdSe量子点;合成的工艺条件会显著影响CdSe/ZnS核壳结构量子点的荧光性能.     

亚微米级复合材料微粒合成研究

在乙醇-水混合溶剂中,用过硫酸钾(KPS)作为引发剂,通过乳液聚合作用来合成直径为375nm的聚苯乙烯(PSt)微球,并作为种子用于种子乳液聚合.用PEGm大分子单体作为稳定剂、偶氮二异丁腈作为引发剂,采用种子乳液聚合法,聚合苯乙烯和丙烯腈,制得特殊形态的亚微米尺寸的PEGm接枝共聚复合颗粒PEGm-g-PSAN.扫描电子显微镜(SEM)显示苯乙烯和丙烯腈同时促成了特殊形态.苯乙烯和丙烯腈的浓度、总单体浓度、引发剂类型和单体加入方式显著影响复合聚合物颗粒的形态.     

双功能荧光——磁性复合微球的合成研究

双功能荧光-磁性复合微球同时具有荧光量子点和磁性颗粒的优良特性，在生物、化学、医学等交叉科学领域有着广阔的应用前景。本文综述了双功能荧光-磁性复合微球的合成方法，主要有包覆法、偶联法和种晶生长法，介绍了各自的优缺点，结合当前的研究现状，分析了其在制各双功能荧光-磁性复合微球方面的应用情况和仍需解决的问题。     

硅壳包裹核/壳型CdSe/CdS纳米晶的制备与性能研究

采用低温水热技术,分别以柠檬酸、聚乙二醇(PEG400)和甲硫氨酸为稳定剂,在水相中合成了核壳型CdSe/CdS量子点,研究了稳定剂、CdSe与CdS物质的量比对量子点发光性能和结构的影响。XRD结果表明,当CdSe∶CdS在1∶3~4时,CdS主要在CdSe的外延生长,形成核壳型纳米粒子,当比例达到1∶5时,CdS单独成晶现象严重。CdSe∶CdS=1∶4时,核壳型量子点具有较高的荧光发射效率。TEM研究表明CdS在CdSe外表面生长形成较为完整的壳层,有效钝化CdSe表面,减少表面缺陷,从而显著提高CdSe量子点的发光效率。CdSe核尺寸为2~3nm的核壳型纳米粒子外包裹一层SiO2壳后,荧光发射效率没有显著提高,发射峰位置无明显红移。量子点包壳后能有效提高该量子点的光化学稳定性,提高量子点的生物相容性。     

无皂乳液聚合法制备亚微米级单分散聚苯乙烯微球

采用无皂乳液聚合法制备了亚微米级聚苯乙烯(PS)微球,考察了苯乙烯(St)单体浓度、引发剂过硫酸钾(K2S2O8)浓度、离子强度(氯化钠浓度)与PS微球粒径及其分布的关系。然后通过加入微量乳化剂或β-环糊精对无皂乳液聚合法进行改进,研究了改进效果。结果表明,PS微球的粒径随St单体浓度和氯化钠浓度的增加而增加、随K2S2O8浓度的增加而减小,通过调节这3种原料的浓度,可制得粒径在450~1000 nm且单分散系数小于0.08的PS微球,但产品收率较低,仅为30%左右。在相同的合成条件下,加入微量乳化剂可制得粒径在100~350 nm且单分散系数小于0.05的PS微球,产品收率提高到75%左右;加入微量β-环糊精可制得粒径在300 nm左右且单分散系数小于0.08的PS微球,产品收率可达80%且反应时间大幅缩短,由原来的12 h缩减到5 h。     

Morphology-controlled synthesis of CdSe microspheres on graphene oxide sheets and their photocatalytic properties

Different morphologies of CdSe microspheres have been synthesized on reduced graphene oxide (rGO) sheets by a simple hydrothermal process using Cadmium nitrate and Se powder as the raw materials. The hybrid CdSe/rGO samples were intensively investigated by XRD, EDS, XPS, SEM and UV–vis absorption spectrum. It was found that the EDTA/Cd²⁺ molar ratio is crucial for the formation of morphology of CdSe grown on rGO sheets. The results of XRD reveal that the as-prepared CdSe microspheres have zinc blend structure. The results of Raman spectra, EDS, XPS and SEM show that the CdSe microspheres are grown on rGO sheets. In addition, UV–vis absorption spectrum indicates that the CdSe/rGO nanocomposites are believed to serve as photosensitizers to extend the absorption spectrum to visible light region. Superior photocatalytic activity of urchin-like CdSe microspheres grown on rGO sheets relative to those of other CdSe/rGO nanocomposites was observed under visible light irradiation. The growth mechanism for the formation of CdSe microspheres grown on rGO sheets was also described.     

钴离子掺杂聚多巴胺/聚苯乙烯复合材料

为实现多巴胺的高效聚合,将Co~(2+)引入多巴胺反应体系中,Co~(2+)的催化作用实现了多巴胺的快速聚合。在聚苯乙烯(PS)微球上黏附聚多巴胺(PDA),与不加金属离子的反应相比,当添加的CoCl_2·6H_2O对多巴胺的物质的量分数为40%时,得到相同PDA含量的复合微球的反应时间可以从16 h缩短至1 h,并且复合微球中PDA以及Co含量随着CoCl_2·6H_2O添加量的增加以及反应时间的延长而增加。复合微球粉末经过热压得到的复合材料具有三维网络结构,Co~(2+)的加入使得PDA与PS具有更好的相容性。PDA·Co/PS复合材料的热性能和力学性能比PDA/PS有更多的提升。     

Synthesis of Low-Density Heat-Resisting Polystyrene/Graphite Composite Microspheres Used as Water Carrying Fracturing Proppants

Low-density heat resistamt, low-cost polystyrene (PS)/graphite microspheres were successfully synthesized via in situ suspension polymerization. Scanning electron microscopy (SEM) indicated that PS/graphite composite microspheres had good sphericity, and graphite particles were evenly dispersed in microspheres. Furthermore, density analysis illustrated that the density of composites was about 1.025–1.185 g/cm³ with good suitability for carrying water. Thermodynamic testing revealed that the thermostability of the composite was dramatically improved by the introduction of graphite, which is used deep underground. In addition, the percentage of damage decreased to 1.3% with graphite ratio of 2.5% at 68 MPa. Therefore, PS/Graphite composite microspheres possess entirely feasible applications in oil exploitation as pure water carrying petroleum proppants.     

High photonic effect of organic dye degradation by CdSe–graphene–TiO2 particles

Photocatalytic activity of CdSe (cadmium selenide) decorated graphene composites coupled with TiO₂ (titanium oxide) was investigated with organic dye solutions. The characterizations of composites were studied by X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM), and with transmission electron microscope (TEM). The degradation of methyl orange (MO) and rhodamine B (RhB) was observed by measuring the decrease in the concentration by UV spectrophotometer. The synergistic effect of graphene on CdSe and TiO₂ was demonstrated by comparative study. The composites were tested for recyclability, investigating the stability of CdSe–graphene/TiO₂ composites.     

Enhanced photoelectric properties of CdSe/graphene composites with various contents of graphene

CdSe/graphene composites with different contents of graphene were prepared by the solvothermal method. The composites were characterized by X-ray diffraction, scanning electron microscope and further investigated by transient photocurrent responses and electrochemical impedance spectroscopy. Compared with pure CdSe particles, CdSe/graphene composites show improved photocurrent responses and decreased electron-transfer resistance due to the presence of graphene, which acts as an electron collector and transporter as well as the supporting matrix for CdSe particles. The composites were synthesized by varying the graphene content from 0.5 wt% to 6 wt%, which has been experienced to exert great influence on the photoelectric characteristics of CdSe/graphene composites. A higher photocurrent density and smaller arc radius can be observed for 0.5% CdSe/graphene composites.     

Surface plasmon enhanced energy transfer in metal-semiconductor hybrid nanostructures

We report a type of hybrid nanostructures composed of ZnO nanoparticles, CdSe/ZnS core/shell quantum dots (QDs), and Ag nanoprisms. With ultraviolet light illumination, the energy absorbed by ZnO nanoparticles was transferred to the CdSe/ZnS core/shell QDs inducing a photoluminescence (PL) emission. To enhance the PL emission, Ag nanoprisms were doped in the ZnO nanoparticles and the QDs. Enhanced energy transfer from the ZnO nanoparticles to the QDs via the surface plasmon effect of the Ag nanoprisms was also demonstrated. The PL emission dependence was investigated as a function of the doped Ag nanoprism concentration and a 7.4 times PL enhancement was obtained at an Ag nanoprism concentration of 5 × 10(-8) M.     

硒化镉量子点的二氧化硅包覆

将油溶性、单分散、高荧光强度的CdSe荧光纳米晶用Stber方法成功地制备了SiO2包覆的荧光纳米晶,包覆后的纳米晶在水中和醇中有良好的溶解性,具有非常好的化学稳定性。SiO2包覆后的纳米晶也具有较强的荧光特性。..     

单分散氢氧化钙/聚苯乙烯微球的制备与表征

以葡萄糖水溶液为反应介质,在氧化钙消化成氢氧化钙的过程中,加入苯乙烯单体和引发剂,采用原位悬浮聚合法成功制备了聚苯乙烯(PS)包覆氢氧化钙[Ca(OH)2]形成Ca(OH)2/PS微球.考察了葡萄糖水溶液、苯乙烯、稳定剂聚乙烯醇以及反应温度对单分散Ca(OH)2/PS微球的粒径及粒子分散系数的影响,得出较佳合成条件.在较佳条件下制备的Ca(OH)2/PS微球平均粒径为30～40 μm,粒子分散系数为0.08～0.10.扫描电镜照片表明,Ca(OH)2/PS具有良好的球形度,表面光滑、无破损.红外光谱表征显示,产物为Ca(OH)2/PS微球.