聚乙烯吡咯烷酮硫脲修饰CdS纳米粒子的制备

用硫脲为表面修饰剂,并用PVP(聚乙烯吡咯烷酮)为稳定剂在乙醇水溶液中合成了粒径分布均匀、性能稳定、有机物修饰的CdS纳米颗粒.重点分析了硫脲的引入对CdS纳米粒子晶体结构、粒径分布、紫外可见吸收光谱、红外光谱、光致荧光光谱(PL)的影响.发现硫脲修饰使得CdS纳米粒子的粒径更小,粒径分布更加均匀,并且有效地抑止了PVP对CdS荧光淬灭,在PL光谱上观察到了CdS的带隙发光.     

复合结构纳米晶CdS：Cu/CdS的制备及光学特性

在非配位溶剂中合成了高质量的CdS纳米晶核,并利用Cu2+离子对其进行掺杂,制备了CdS:Cu纳米晶.通过进一步采用连续离子层吸附反应的方法对CdS:Cu纳米晶进行表面修饰,得到CdS:Cu/CdS复合结构纳米晶.利用X射线衍射(XRD),透射电镜(TEM),紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)对其结构、形貌以及光学性质进行了表征和分析,结果表明:所制备的复合结构CdS:Cu/CdS纳米晶为立方闪锌矿结构;与CdS纳米晶核相比,掺杂Cu2+可以使其表面态发光发生红移;在CdS:Cu纳米晶中,通过改变掺杂Cu2+的浓度,可以实现表面态发光在570和620nm之间的连续调节.与未经包覆的CdS:Cu纳米晶相比,包覆层CdS增强了纳米晶CdS:Cu的稳定性.     

室温水溶液法制备银花状球及其光学特性

利用水溶液法,以柠檬酸和表面活性剂聚乙烯吡咯烷酮(PVP)为辅助,在室温环境中反应2h成功合成了Ag花状球。用粉末X射线衍射仪(XRD)、X射线能谱仪(EDX)、场发射扫描电子显微镜(FESEM)以及紫外-可见分光光度计(UV-Vis)等手段对产物进行了表征。研究表明,产物结晶性良好,产率高,形貌规整且粒径分布均匀,花状球的平均直径为900nm。产物于242nm处产生强的紫外吸收峰。通过对Ag花状球形成机理和实验条件进行系统探讨,提出了三步反应机理,同时发现柠檬酸和表面活性剂PVP对产物的形貌和尺寸起着关键作用。     

化学水浴法制备CuS纳米花状球及其光学性能研究

利用化学水浴法,以表面活性剂十二烷基苯磺酸钠(SDBS)为辅助,在100℃反应4h合成了CuS纳米花状球。用粉末X射线衍射仪(XRD)、X射线能谱仪(EDX)、场发射扫描电子显微镜(FESEM)、紫外-可见分光光度计(UV-Vis)以及荧光光谱仪(PL)等手段对产物进行了表征。研究表明,产物结晶性良好,产率高,形貌规整且粒径分布均匀,纳米花状球的平均直径为350nm。产物在370nm波长光的激发下,于可见光区域486nm处产生强的荧光发射峰,发生了明显的蓝移。通过对CuS纳米花状球形成机理和实验条件进行系统探讨,提出了3步反应机理,同时发现表面活性剂SDBS对产物的形貌和尺寸起着关键作用。     

利用水溶性聚合物PVP作稳定剂合成CdS、CdSe半导体纳米晶体

以水溶性聚合物聚乙烯基吡咯烷酮(PVP)作分散剂,在水相溶液中制备CdS/PVP纳米粒子.通过控制水溶液体系的pH值或者分散剂含量,实现了纳米粒子从球形到棒状的转变;同时探讨了Cd/S比值变化对纳米粒子结构的影响.利用原子力显微镜(AFM)表征CdS/PVP纳米体系的形貌,并进一步利用透射电镜(TEM)、红外光谱(FT-IR)和粉末X-射线衍射(XRD)等对其结构进行了分析和研究.     

复合结构纳米晶CdS∶Cu/CdS的制备及光学特性

在非配位溶剂中合成了高质量的CdS纳米晶核,并利用Cu²⁺离子对其进行掺杂,制备了CdS∶Cu纳米晶.通过进一步采用连续离子层吸附反应的方法对CdS∶Cu纳米晶进行表面修饰,得到CdS∶Cu/CdS复合结构纳米晶.利用X射线衍射(XRD),透射电镜(TEM),紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)对其结构、形貌以及光学性质进行了表征和分析,结果表明:所制备的复合结构CdS∶Cu/CdS纳米晶为立方闪锌矿结构;与CdS纳米晶核相比,掺杂Cu²⁺可以使其表面态发光发生红移;在CdS∶Cu纳米晶中,通过改变掺杂Cu²⁺的浓度,可以实现表面态发光在570和620nm之间的连续调节.与未经包覆的CdS∶Cu纳米晶相比,包覆层CdS增强了纳米晶CdS∶Cu的稳定性.     

原位法P3HT-COOH/CdS纳米复合材料的制备与表征

以二水乙酸镉(Cd(OOCCH3)2·2H2O)为镉源,硫粉(S)为硫源,二氯苯(DCB)和二甲基亚砜(DMSO)为混合溶剂,末端羧基化聚-3-己基噻吩(P3HT-COOH)为模板,原位法合成了P3HT-COOH/CdS纳米复合材料;并利用核磁共振氢谱、傅里叶变换红外光谱、X射线衍射、透射电子显微镜、紫外-可见光谱和荧光光谱等分析测试方法对其组成、形貌、光电性能等进行了表征。研究了不同反应温度及S/Cd摩尔比对复合材料形貌及光电性能的影响。实验结果表明,所合成的CdS纳米粒子均匀分布在P3HT-COOH/CdS复合材料中;CdS的尺寸和分布不仅受温度影响,还很大程度上受S/Cd摩尔比的影响;P3HT-COOH/CdS纳米复合材料有较强的荧光淬灭,表明CdS与P3HT-COOH之间有电荷转移。     

花状纳米Zno的低温水浴制备及生长机理

以氯化锌和氢氧化钠为反应原料,利用水浴恒温加热,在溶液中直接制备出呈花状形貌的纳米ZnO;采用扫描电镜、X射线衍射、透射电子显微镜等分析方法对所得产物的形貌和结构进行了表征,结果表明,在低温(45℃)时可制备出大量呈花状形貌的纳米ZnO.     

一步沉淀法制备三维分等级花状α-Bi2 O3微球及其光性能

以乙醇-水为溶剂体系、丙三醇为封端剂,在低温(95℃)及常压下,采用水相一步沉淀法,以Bi(NO_3)_3·5H_2O为铋源、NaOH为沉淀剂,反应1 h制备出两种三维分等级花状α-Bi_2O_3微球。采用X射线衍射仪(XRD)和场发射扫描电子显微镜镜(FE-SEM)表征Bi_2O_3样品的晶型和微观形貌。结果表明,样品均为α相,尺度在微米级,随丙三醇浓度不同,微观形貌分别为纳米立方体3D自组装分等级花状微球和一维纳米棒自组装分等级花状微球。初步分析了特殊微观形貌形成的机理。紫外-可见光谱(UV-Vis)分析表明,样品均在紫外-可见光区有显著的光吸收,两种样品的禁带宽度分别为2.76 eV和2.70 eV,属于电子从价带跃迁到导带引起的吸收,为Bi_2O_3的直接带隙吸收。荧光光谱(PL)分析表明,样品在400～600 nm均具有五个发射谱带(谱带中心位于450 nm、466 nm、480 nm、490 nm和562 nm处)。微观形貌影响荧光发射谱带的波形与强度,纳米棒自组装而成的花状分等级微球的荧光强度稍弱。     

花状纳米铜的制备及抗菌性能

采用液相化学还原法分别制备了聚乙烯吡咯烷酮(PVP)和羧甲基壳聚糖(NOCC)修饰的花状铜纳米材料。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)等对所得样品的形貌和结构进行了表征。结果表明,所制备样品具有面心立方铜的晶体结构,SEM观察下,铜纳米微粒以PVP和NOCC为软模板自组装生长花状纳米结构。分别通过抑菌圈法和肉汤稀释法测试了样品对3种常见菌种的抑菌圈直径、最小抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果表明,所制备样品对大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)及绿脓杆菌(P.aeruginosa)均具有优异的抑菌杀菌作用。     

Synthesis and characterizations of polycrystalline walnut-like CdS nanoparticle by solvothermal method with PVP as stabilizer

A wide range of cadmium sulfide (CdS) 3D polycrystalline walnut-like nanocrystals were prepared by solvothermal method with polyvinylpyrrolidone (PVP) as stabilizer. The morphology, structure, and phase composition of the as-prepared CdS nanoparticles were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED)). The optical properties of CdS were characterized by photoluminescence (PL) spectra. The paper showed that when the proper dosage of PVP (0.12 g 50 mL⁻¹) and the temperature of reaction (120 °C) were taken, continuous polycrystalline nanoparticles with regular morphology were obtained. The mechanism for the PVP-assisted synthesis of CdS 3D nanostructures and the growth process of CdS nanoparticles via Ostwald Ripening process under different temperatures with different dosages of PVP were also investigated. A sensitive electrochemical detection device of DNA hybridization using a paste glass carbon electrode (GCE) assembled by the PVP-capped CdS nanoparticles and immobilizing DNA probe was developed as a novel application of nano-semiconductors such as CdS to achieve a notable amplification in sensor response.     

One-dimensional cadmium sulfide (CdS) nanostructures by the solvothermal process: Controlling crystal structure and morphology aided by different solvents

Cadmium sulfide (CdS) nanowires and nanorods with different aspect ratios were successfully synthesized by the solvothermal method aided with various solvents, namely ethylenediamine, ethanolamine and triethylene tetraamine. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that, highly pure CdS nanostructures were crystallized with different structures and preferable growth orientations depending on solvent nature. Field emission electron microscope (FE-SEM) images showed that the aspect ratio of CdS nanostructures depends upon the dielectric constant and boiling temperature of solvents. CdS nanostructures with the highest aspect ratio in the form of nanowire were obtained using ethylenediamine, whereas CdS nanorods were produced in the presence of ethanolamine and triethylene tetraamine solvents. The absorption edge of CdS nanowires and nanorods showed a blue shift compared with that of bulk CdS due to an increase in their band gap energies.     

Tailor of ZnO morphology by heterogeneous nucleation in the aqueous solution

The umbrella-like ZnO nanostructures have been prepared by the morphological tailoring in the aqueous solution at 95 °C in the addition of heterogeneous seeds such as MnO₂ and CdS nanoparticles. The morphology and structure of as-synthesized umbrella-like ZnO nanostructures have been characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), electron energy loss spectroscopy (EELS), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The heterogeneous seeds play the critical role for the formation of umbrella-like ZnO nanostructures. Furthermore, the formation mechanism of the umbrella-like nanostructures has been phenomenally presented.     

Microwave-assisted synthesis of barium tungstate nanosheets and nanobelts by using polymer PVP micelle as templates

Single-crystal BaWO₄ nanosheets and nanobelts have been successfully synthesized by using polymer PVP micelle as templates in a reflux system under microwave irradiation. Our result shows that the concentration of PVP aqueous solutions played an important role in the formation of BaWO₄ crystal with different morphologies. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and electron diffraction (ED).     

Morphology-controlled synthesis of silver nanostructures via a solvothermal method

Silver nanostructures have been synthesized by a simple solvothermal method in the presence of poly(vinylpyrrolidone) (PVP). Typically, different exotic agents (NaOH, KBr, NaCl) are added into the reaction system. The anions (OH⁻, Cl⁻, Br⁻) from these agents can combine Ag⁺ to form silver salt colloids (AgOH, AgBr and AgCl), decreasing the concentration of free Ag⁺ in the initial formation of silver seeds. However, different release rates of Ag⁺ from these colloids to the solution in the subsequent reaction may play different roles in the growth of silver seeds. The as-prepared silver nanostructures were characterized by UV–vis absorption spectrum, X-ray diffraction (XRD) and field emission scanning electron microscope (FSEM). It is found that silver nanostructures with various shapes can be obtained by the addition of different exotic agents. Finally, our work provides a simple route to synthesize silver nanostructures with controllable morphologies.     

ZnO准一维纳米结构生长形态的演化机理

利用气相生长系统,通过调控实验参数,制备了多种形貌的ZnO准一维结构,如纳米条带、[011-0]和[21-1-0]取向的单侧生齿的梳状纳米条带、微米尺度的梳状结构,由多节状六角棱柱和八角棱柱组装成的微米条带等.通过X射线衍射、扫描电子显微镜及其所加载的能谱分析和背散射电子衍射仪、高分辨透射电子显微镜等分析技术, 对其中具有代表性的介观结构进行了系统的形貌分析和细致的结构解析.分析出基本的结构单元及其复合体, 揭示了显微尺度下ZnO晶体的外形多样性以及其形态演化中的关联和规律,即ZnO纳米条带、梳状结构和多节状微米条带具有晶体结构上的同一性.     

Synthesis and growth mechanism of triangular Mn doped CdS nanowires

Triangular Mn-doped CdS nanowires (NWs) were prepared by thermal evaporation of a mixture of CdS and MnCl₂. The morphologies and detailed structures were characterized by a scanning electron microscope, X-ray diffraction, and transmission electron microscope. The Mn concentration plays an important role in synthesis of the triangular NWs. The morphologies can be varied from hexagonal to triangular by adjusting the amount of MnCl₂ in the reaction mixture. The oriented attachment mechanism is demonstrated to be the most suitable mechanism to explain the growth process of the triangular NWs. The photoluminescence shows the intensity of Mn²⁺ emission peak increases as the molar ratio of MnCl₂increases.     

Dependence of photovoltaic performance of solvothermally prepared CdS/CdTe solar cells on morphology and thickness of window and absorber layers

In the present work a new strategy for straightforward fabrication of CdS/CdTe solar cells, containing CdS nanowires and nanoparticles as a window layer and CdTe nanoparticles and microparticles as an absorber layer, are reported. CdS and CdTe nanostructures were synthesized by solvothermal method. X-ray diffraction analysis revealed that highly pure and crystallized CdS nanowires and nanoparticles with hexagonal structure and CdTe nanoparticles with cubic structure were obtained. Atomic force microscope and field emission scanning electron microscope images showed that CdS nanowires with length of several μm and average diameter of 35 nm, CdS nanoparticles with average particle size of 32 nm and CdTe nanoparticles with average particle size of 43 nm, were uniformly coated on the substrate by the homemade formulated pastes. Based on ultraviolet–visible absorption spectra, the band gap energies of CdS nanowires, CdS nanoparticles and CdTe nanoparticles were calculated 2.80, 2.65 and 1.64 eV, respectively. It was found that, the photovoltaic performance of the solar cells depends on thickness of CdTe and CdS films, reaching a maximum at a specific value of 6 μm and 225 nm, respectively. For such cell made of CdS nanowires and CdTe nanoparticles the V_OC, J_SC, fill factor and power conversion efficiency were calculated 0.62 V, 6.82 mA/cm², 59.7 and 2.53 %, respectively. Moreover, photovoltaic characteristics of the solar cells were dependent on CdTe and CdS morphologies. CdS/CdTe solar cell made of CdTe and CdS nanoparticles had the highest cell efficiency (i.e., 2.73 %) amongst all fabricated solar cells. The presented strategy would open up new concept for fabrication of low-cost CdS/CdTe solar cells due to employment of a simple chemical route rather than the vapor phase methods.     

CdS hierarchical spindles: Structural defects and properties

Hydrothermal process has been successfully applied to synthesize CdS hierarchical spindles. The compositions and morphologies of the as-produced CdS were investigated through X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. It is found that the hexagonal wurtzite-structured CdS spindles are endowed with hierarchical morphologies with the branches nearly perpendicular to the trunks. Some of the structural defects are also detected by TEM. Furthermore, the absorption and emission spectral properties were studied using UV-Vis spectrometer and photoluminescence spectrometer, respectively. It is speculated that the red shift of absorption edge and the enhanced deep-level (DL) emission are all related to the structural defects of the as-prepared CdS hierarchical spindles.     

CdS microflowers and interpenetrated nanorods grown on Si substrate: Structural,optical properties and growth mechanism

CdS semiconductor with different morphologies have been achieved by simple thermal evaporation of CdS powder at 1050 °C in a flowing Ar atmosphere. The products were characterized by X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy and Photoluminescence. microflowers and interpenetrative nanorods of CdS were formed on catalyst free Si wafers at a temperature of 700 °C and 600 °C respectively. The flower like structures are composed of many interleaving nanorods which have the uniform diameter of about 700 nm and a well crystalline structure with [0001] as growth direction. The interpenetrative nanorods are found to be bounded with six side facets. X-ray diffraction studies revealed the hexagonal structure in both the products. The formation mechanism of microflowers and interpenetrated nanorods was discussed on the basis of nucleation growth kinetics. Room temperature photoluminescence spectra showed a strong green emission band (at ∼510 nm) from the CdS flower like structures, but on the other hand a red emission shoulder along with strong green emission band was observed for interpenetrative nanorods. These CdS micro/nanostructures with abundant morphologies may find applications in various micro/nanodevices, and the kinetics-driven morphology might be exploited to synthesize similar structures of other functional II–VI semiconductors.