共查询到20条相似文献,搜索用时 187 毫秒
1.
2.
3.
4.
以聚乙烯亚胺(PEI)功能化的石墨烯(PEI-GNs)为载体, 利用电化学还原法制备了Pd/PEI-GNs复合物. 采用红外光谱仪、 X射线光电子能谱仪、 X射线粉末衍射仪和扫描电子显微镜等对复合物的组成、 结构和形态进行了表征. 结果表明, Pd/PEI-GNs复合物中Pd颗粒均匀分散在PEI-GNs基底上. 采用循环伏安法、 交流阻抗法和计时电流法等电化学方法研究了Pd/PEI-GNs复合物的电化学性能. 结果表明, 制备的复合物催化剂对对硝基苯酚还原具有较好的催化活性和稳定性, 这主要是由于Pd纳米颗粒在PEI-GNs载体上均匀分散以及PEI-GNs优异的电子传递能力. 相似文献
5.
6.
用水热方法制备了CdSe量子点(CdSe QDs)并通过溶胶-凝胶法制备了量子点掺杂改性的纳米TiO2复合物。运用多种方法对此复合物进行表征,并对其光催化性能进行研究。结果表明:1在其制备焙烧过程中,CdSe QDs已掺杂进入TiO2纳米颗粒中形成纳米复合物;2 CdSe QDs的引入增强了TiO2的吸光性,改善了TiO2在可见光区的吸光效率;3 TiO2的原始晶体结构在焙烧过程中发生变化,形成了两种晶相的混晶,有利于其光催化活性的改善;此外纳米TiO2复合物的表面电子结构以及吸附性能等对其光催化作用也有协同作用,使其催化性能进一步提高。 相似文献
7.
采用共沉淀法制备了Fe3O4磁性纳米粒子,将其负载于氨基吡啶修饰多壁碳纳米管(MWCNT-AP)上,得到具有良好的分散性和超顺磁性的Fe3O4/MWCNT-AP复合物.通过傅里叶变换红外(FT-IR)光谱、X射线衍射(XRD)和磁滞回线测量等方法对Fe3O4/MWCNT-AP复合物进行了表征.扫描电镜(TEM)结果表明:Fe3O4磁性纳米粒子多集中于碳纳米管MWCNT-AP的端部,形成的复合物在极性溶剂中具有良好的分散性和超顺磁性;辣根过氧化酶(HRP)可通过物理作用吸附于Fe3O4/MWCNT-AP复合物表面.酸性条件下(pH 4.0),Fe3O4/MWCNT-AP复合物使HRP的最大反应速率(Vmax)提高了3倍. 相似文献
8.
9.
10.
11.
High-quality ZnS, ZnS:Mn2+, and ZnS:Mn2+/ZnS (core/shell) nanocrystals (NCs) were synthesized via a high-boiling solvent process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The monodisperse ZnS NCs (size = 8 nm), which self-assembled into several micrometer-sized domains, were achieved by adopting poly(ethylene glycol) (PEG) in the reaction process (without using a size-selection process). The obtained ZnS:Mn2+ and ZnS:Mn2+/ZnS core/shell NCs are highly crystalline and quasimonodisperse with an average particle size of 6.1 and 8.4 nm, respectively. All of the as-formed NCs can be well dispersed in hexane to form stable and clear colloidal solutions, which show strong visible emission (blue for ZnS and red-orange for ZnS:Mn2+ and ZnS:Mn2+/ZnS) under UV excitation. The growth of a ZnS shell on ZnS:Mn2+ NCs, that is, the formation of ZnS:Mn2+/ZnS core/shell NCs, resulted in a 30% enhancement in the PL intensity with respect to that of bare ZnS:Mn2+ NCs due to the elimination of the surface defects. 相似文献
12.
Wentao Zhang Hong-Ro Lee 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1623-1631
Methacrylic acid (MAA) was used as a manganese carrier to prepare ZnS/MAA-Mn particles, and ZnS/ZnS:Mn phosphors were formed from ZnS/MAA-Mn by ion substitution through heat treatment. After silica coating on surface by chemical precipitation method with tetraethyl orthosilicate (TEOS), ZnS/ZnS:Mn/SiO2 phosphors were prepared successfully as a new core/shell structure compound. The thickness of layers was controlled by adjusting concentrations of manganese (II) acetate (Mn(CH3COO)2) and TEOS. Structure, morphology, and composition of prepared phosphors were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence (PL) properties of ZnS with different Mn2+ content were analyzed by PL spectrometer. PL emission intensity and PL stability were analyzed for evaluating effects of silica coating and Mn2+ activator doping. As a result, the structure of two layers could be observed, and optimum composition of ZnS/ZnS:Mn/SiO2 structure was also obtained. 相似文献
13.
Hydrophobic Mn-doped ZnS quantum dots (Mn:ZnS d-dots) were made to be water soluble by coating a monolayer of mercaptopropionic acid (MPA). It is found that the PL efficiency of Mn:ZnS d-dots with various shell thicknesses were all improved after thiol (MPA) ligand exchange. We attribute their PL enhancement to the effective surface passivation induced by the thiol ligand and significantly decrease of holes transfer from d-dots to ligands. The PL QY of as-synthesized thiol-coated d-dots can reach as high as 50%. These efficient, stable, and water soluble d-dots are confirmed to be suitable for biomedical applications. 相似文献
14.
Bohua Dong Lixin Cao Ge Su Wei Liu Hua Qu Daixun Jiang 《Journal of colloid and interface science》2009,339(1):78-82
Silica-coated ZnS:Mn nanoparticles were synthesized by coating hydrophobic ZnS:Mn nanoparticles with silica shell through microemulsion. The core–shell structural nanoparticles were confirmed by X-ray diffraction (XRD) patterns, high-resolution transmission electron microscope (HRTEM) images and energy dispersive spectroscopy (EDS) measurements. Results show that each core–shell nanoparticle contains single ZnS:Mn nanoparticle within monodisperse silica nanospheres (40 nm). Photoluminescence (PL) spectroscopy and UV–vis spectrum were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnS:Mn nanoparticles, the silica-coated ZnS:Mn nanoparticles have the improved PL intensity as well as good photostability. The obtained silica-coated ZnS:Mn nanoparticles are water-soluble and have fluorescence sensitivity to Cu2+ ions. Quenching of fluorescence intensity of the silica-coated nanoparticles allows the detection of Cu2+ concentrations as low as 7.3 × 10−9 mol L−1, thus affording a very sensitive detection system for this chemical species. The possible quenching mechanism is discussed. 相似文献
15.
High-quality Mn doped ZnS d-dots were successfully synthesized via an alternative route based on the solvothermal method using oleic acid as stabilizing agent. X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as photoluminescence (PL) spectra were employed to characterize the obtained samples. The as-obtained d-dots are highly crystalline and uniform sized, and they can be well dispersed in hexane to form stable and clear colloidal solution. The optical properties of the d-dots with different Mn doped concentration are investigated in detail. The Mn doped ZnS d-dots have two emission bands, including surface state emission (blue) and Mn emission (orange), which are both sensitivity to the Mn doped concentration. By varying the Mn doped concentration, the relative PL intensities of dual-color emissions can be well manipulated, showing their application in tunable color output. Furthermore, a subsequent ligand exchange has been introduced to give the d-dots hydrophilic surfaces, which are favorable for biological applications. 相似文献
16.
以SnCl2•2H2O、SbCl3为原料, 通过溶胶-凝胶法制备SnO2:Sb干凝胶. 利用干凝胶氧化过程中的部分升华产物对新制的ZnS:Mn荧光粉进行了表面处理. 在固定氧气流量和氧化时间的条件下, 考察了SnO2:Sb干凝胶与ZnS:Mn荧光粉的质量比和氧化温度对处理后荧光粉电阻率的影响. 当干凝胶粉与荧光粉的质量比为3.0, 氧化温度为500 ℃处理后荧光粉的电阻率明显下降. 对处理后的荧光粉进行了室温光致荧光(PL)光谱、X射线衍射(XRD)以及透射电镜(TEM)分析. 结果表明对荧光粉进行表面处理没有改变荧光粉的光致发光性质和晶体结构. 相似文献
17.
18.
以溶于十八烯的Se作为Se前驱体,在无膦条件下制备得到了具有较高量子产率的Mn:ZnSe纳米晶.为了进一步提高纳米晶的稳定性和发光强度,运用外延生长的方法进行ZnS壳层包覆并得到了具有核-壳结构的Mn:ZnSe/ZnS纳米晶.X射线衍射、透射电子显微镜及吸收和荧光光谱测试结果表明,该方法合成的Mn:ZnSe纳米晶以及核-壳结构Mn:ZnSe/ZnS纳米晶均为闪锌矿结构,具有良好的单分散性,包覆ZnS外壳层后量子产率可达到60%以上.此外,对ZnS壳层厚度和Mn2+的掺杂量对Mn:ZnSe/ZnS纳米晶发光强度的影响及发光机制也进行了初步讨论. 相似文献
19.
Manganese-doped zinc sulfide quantum dots (Mn:ZnS d-dots) with high optical quality, pure dopant emission of 55-65% photoluminescence quantum yield, were synthesized in octadecene media with generic starting materials, namely, zinc (manganese) carboxylic acid salts, S powder, and dodecanethiol (DDT) based on a "nucleation doping" strategy. The optical properties and structure of the obtained Mn:ZnS d-dots have been characterized by UV-vis, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The resulting nearly monodisperse d-dots were found to be of spherical shape with a zinc-blende crystal structure. The influences of various experimental variables, including the reaction temperature for the MnS core nanocluster and ZnS host material, the amount of octadecene (ODE)-S, DDT, as well as Zn/Mn ratio have been systematically investigated. The use of DDT as capping ligand ensured the reproducible access to a stable small-sized MnS core. This paves the way for reproducibly obtaining highly luminescent d-dots. Programmed overcoating temperature for growth of ZnS shell was employed to realize balanced diffusion of the Mn ions in the d-dots. 相似文献
20.
通过高压静电纺丝技术制备了聚乙烯醇/聚乙烯亚胺(PVA/PEI)纳米纤维膜, 对纤维膜进行功能化使其转化为对重金属离子具有高络合能力的聚乙烯醇/二硫代氨基甲酸盐功能化聚乙烯亚胺(PVA/DTC)纳米纤维膜. 研究了PVA/PEI纳米纤维膜的交联和功能化以及PVA/DTC纤维膜对铅离子的吸附行为. 结果表明, 高压静电纺丝法可制备出纤维直径分布均匀、 形貌良好的纳米纤维膜, 且交联、 功能化后仍能保持蓬松纳米纤维状的网状结构. PVA/DTC纳米纤维膜对铅离子吸附速率快, 吸附量容量高, 且具有良好的再生吸附能力, 是一种潜在的重金属离子高效吸附材料. 相似文献