化学氧化聚合法制备聚噻吩及其表征

在不同温度、浓度、反应时间下通过化学氧化聚合制备不同的聚噻吩样品。用扫描电镜对样品形貌进行了表征,分析不同反应时间、不同试剂浓度下样品的形貌。再通过Raman光谱,XRD,分光光度计等技术进行表征。结果表明,不同的制备条件影响到聚噻吩的形貌及性能,温度的不同对形貌影响较大。通过对吸收光谱的研究可知,随着反应温度的增加,吸收峰值在变大,但光谱吸收范围在变小。浓度对样品的颜色及合成效率都有影响,反应时间超过某一数值时就不再影响聚噻吩的合成。     

不同形貌低维纳米／微米CdSe／ZnSe的溶剂热法合成

利用溶剂热法．通过添加不同种类的溶剂及改变反应温度、反应时间．成功合成了具有片状、棒状、球技，圆锥花序状等不同形貌的纳米/微米级硒化镉、硒化锌半导体材料.简单讨论了表面活性剂、反应温度及反应时间对产物形貌及尺寸的影响。所得产物进行了扫描电子显微镜（SEM）、透射电子显微镜（TEM）、能谱（EDS）、X射线折射（XRD）等表征.     

KTa0.6Nb0.4O3粉体溶剂热和水热法合成的对比研究

以Nb2O5和Ta2O5为前驱反应物，KOH为矿化剂，采用水热法和溶剂热法两种合成工艺制备了KTa1-xNbxO3（KTN）陶瓷粉体．实验结果表明，反应溶剂（水／异丙醇）和矿化剂KOH的摩尔浓度是影响KTN粉体结构和形貌的关键因素．采用水热工艺制备的KTN粉体，当KOH浓度达到3mol／L、反应温度为523K、反应时间8h时，开始出现以焦绿石结构为主的KTN粉体；随着KOH的浓度和反应温度的增加，粉体中的钙钛矿结构成分随之增加，而焦绿石结构则逐渐减少，但始终难以完全消除．采用溶剂热法，在KOH浓度1-2mol／L、反应温度523K、反应时间8h的条件下，合成了立方相钙钛矿结构KTa0.6Nb0.4O3陶瓷粉体，KTN晶粒形状呈规则的立方体，尺寸约为30-50nm；最后对溶剂热法合成纳米粉体的机理进行了分析讨论．     

溶剂热法制备Cu2ZnSnS4粉末及其表征

采用溶剂热法, 以CuCl₂·2H₂O、Zn(Ac)₂·2H₂O、SnCl₄·5H₂O作金属源, 硫脲作硫源, 乙二醇作溶剂, PVP作表面活性剂, 制备了Cu₂ZnSnS₄(CZTS)粉末。利用XRD、SEM、Raman、TEM、EDS、UV-Vis吸收光谱探讨了反应温度和反应时间对制备CZTS粉末的相结构、成分、形貌以及光学性能的影响。结果表明: 反应温度和反应时间对CZTS粉末的颗粒形貌和光学性能影响较大, 最佳合成温度为230℃, 反应时间24 h。该条件下生成的CZTS粉末相较为纯净、结晶完全, 形貌为表面嵌有薄片的微球, 各元素原子比接近化学计量比, 光学带隙为1.52 eV, 与太阳能电池所需的最佳带隙接近。并对其形成机理进行了初步探讨。     

K2Ta2O6光催化剂的水热法制备及其光催化性能

以Ta2O5和KOH为原料采用水热法系统地制备了钽酸钾光催化剂。通过XRD、SEM、UV-Vis漫反射等测试手段对样品进行表征,探讨了反应时间、温度、KOH浓度等实验条件对结晶性能和形貌的影响。实验结果表明,水热温度为180℃,反应时间为24h,KOH浓度0.5mol/L条件下合成了结晶完善、粒径200nm左右的焦绿石相K2Ta2O6,其形貌是正八面体形;这种结构能有效地提高K2Ta2O6对藏红T溶液的光催化降解效率。     

低温溶剂热法合成形貌可控的EuS中空微球

采用(Phen)Eu(Et_2CNS2)_3·nH_2O做前驱物,乙腈做反应溶剂,在230℃的低温下,通过溶剂热法首次成功地合成了EuS中空晶体。对样品进行扫描电镜表征,发现EuS晶体是空心微球,通过样品的傅里叶红外光谱和液体紫外可见吸收谱表征,确定了EuS空心微球表面吸附的有机物成分;通过乙腈溶剂热法在不同反应条件的研究得出如下结论:当温度升高,压强增大,样品结晶质量变好,粒径减小;通过改变溶剂热条件,可以合成形貌可控的EuS中空微球。     

磷酸银多面体微晶的水热合成及光催化性能的研究

本文利用水热法合成了Ag3P04多面体微晶光催化剂,用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）对所合成的样品进行了表征,实验结果表明利用水热法于140℃下反应6h制得的Ag3PO4样品为多面体微晶,反应温度、反应时间以及表面活性剂都对多面体微晶的结构与形貌造成影响。在可见光照射下,Ag3PO4多面体微晶样品对甲基橙和罗丹明B溶液有较好的光催化降解作用。     

不同温度下硒化镉(CdSe)量子点的生长及荧光性研究

研究了以氧化镉（CdO）和硒（Se）粉为前驱体,在三辛基膦（TOP）和油酸中合成无机半导体量子点（quantum dots, QDs）CdSe.研究了在不同的反应温度下粒子的生长,通过紫外吸收光谱（UV-Vis）、荧光发射光谱（PL）、透射电子显微镜（TEM）等手段跟踪反应过程并对样品性能进行了表征.实验结果表明,反应温度和反应时间对量子点的生长和荧光性能有很大的影响.     

锂离子电池阴极材料LixNiO2合成

介绍了由氢氧化锂和氢氧化镍（Ⅱ）通过高温法合成氧化镍锂的方法，并讨论了合成条件对产物结构的影响。实验结果表明，反应温度、反应时间、Ｌｉ／Ｎｉ摩尔比对产物结构有国大的影响，并合成出具有高结晶层状结构的ＬｉｘＮｉＯ２。     

水热/溶剂热法合成不同形貌结构光催化剂BiVO4的研究进展

BiVO4光催化剂的颗粒粒径、物相及形貌结构等因素都对其催化性能有显著影响,因此制备粒径、物相及形貌结构可控的BiVO4光催化剂具有重要意义。水热/溶剂热法是目前合成光催化剂BiVO4的一种重要方法,从影响水热/溶剂反应体系的因素方面概述了水热反应温度、反应时间、反应液pH值、表面活性剂以及反应溶剂等对终产物BiVO4的颗粒尺寸、物相结构以及形貌的影响。     

A simple synthesis and characterization of CuS nanocrystals

Water-soluble CuS nanocrystals and nanorods were prepared by reacting copper acetate with thioacetamide in the presence of different surfactants and capping agents. The size of the nanocrystals varied from 3–20 nm depending on the reaction parameters such as concentration, temperature, solvent and the capping agents. The formation of nanocrystals was studied by using UV-visible absorption spectroscopy.     

Large-scale growth of Cu2ZnSnSe4 and Cu2ZnSnSe4/Cu2ZnSnS4 core/shell nanowires

We present a fast and simple protocol for large-scale preparation of quaternary Cu(2)ZnSnSe(4) (CZTSe), as well as CZTSe/Cu(2)ZnSnS(4) (CZTS) core/shell nanowires using CuSe nanowire bundles as self-sacrificial templates. CuSe nanowire bundles were synthesized by reacting Cu(2 - x)Se nanowire bundles with sodium citrate solution. CZTSe nanowires were prepared by reacting CuSe nanowire bundles with Zn(CH(3)COO)(2) and SnCl(2) in triethylene glycol. X-ray diffraction (XRD) and selected area electron diffraction studies show that stannite CZTSe is formed. The formed CZTSe nanowire bundles have diameters of 200-400 nm and lengths of up to hundreds of micrometers. CZTSe/CZTS nanocable bundles with similar morphologies were grown by the addition of some elemental sulfur to the reaction system for growth of CZTSe bundles. The stannite CZTSe/kesterite CZTS core/shell structure of the grown nanocables was confirmed by XRD and high-resolution transmission electron microscope investigation. The influence of S/Se molar ratio in the reaction system on the crystallographic structures and optical properties of CZTSe/CZTS nanocables was studied. The obtained CZTSe/CZTS core/shell nanocable bundles show broad and enhanced optical absorption over the visible and near-infrared region, which is promising for use in photovoltaic applications.     

Hot-injection synthesis and characterization of quaternary Cu2ZnSnSe4 nanocrystals

Cu₂ZnSnSe₄ (CZTSe) is one of promising materials in the use of absorber layers of solar cells. It contains earth-abundant elements of zinc and tin, a near-optimal direct band gap of ∼ 1.5 eV, as well as a large absorption coefficient ∼ 10⁴ cm-1. The CZTSe nanocrystals in oleylamine (OLA) was successfully prepared via hot-injection method. The characterization of its structure, composition, morphology and absorption spectra were done using powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and UV-vis absorption spectra. The results revealed that the monodispersed nanocrystals were single phase polycrystalline within the range of 15-20 nm. Optical measurements showed a direct band gap of 1.52 eV, which was optimal for low cost solar cells. The capping property of OLA was also demonstrated by examining Fourier Transform Infrared Spectroscopy (FTIR) feature peaks of CZTSe and OLA, respectively.     

Low temperature synthesis of colloidal CdSe quantum dots

In this study, the CdSe nanocrystals were prepared in phenyl ether and octyl amine to investigate the variations of their size, bandgap energy, and photoluminescence with growth time and temperature. The sizes of the CdSe nanocrystals were measured using High Resolution Transmission Electron Microscopy (HRTEM), and found to be nearly monodisperse for relatively low growth temperature, 130 degrees C. Their optic properties were characterized by photoluminescence measurements, which showed that the colors of the nanocrystals could be controlled. The bandgap energies of the nanocrystals were calculated theoretically and found to be in accord with quantum confinement theory. This synthetic method requires only a cheap solvent and offers good reproducibility at a lower price.     

Structural and optical properties of the Cu2ZnSnSe4 thin films grown by nano-ink coating and selenization

Quaternary semiconductor Cu₂ZnSnSe₄ (CZTSe) is a very promising alternative to semiconductors based on indium (In) and gallium (Ga) as solar absorber material due to its direct band gap, inherent high absorption coefficient (>10⁴ cm^?1) and abundance of cheap elements zinc (Zn) and tin (Sn). In this study, high quality CZTSe thin films were successfully synthesized by a green and low-cost solution based non-vacuum method, which involves spin coating non-toxic solvent-based CZTSe nano-inks onto Mo coated soda lime glass substrates followed by selenization with elemental Se vapor. The effect of selenization temperature on structural, morphological, compositional and optical properties of CZTSe films are investigated using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and photoluminescence spectroscopy. XRD and Raman analysis indicates that a tetragonal stannite-type structured CZTSe is formed. Depend on the selenization temperature, the dense and compact films with grain sizes from 200 nm (500 °C) up to about 1 μm (580 °C) are obtained. EDS measurement indicates that the composition ratios of the prepared CZTSe films are copper-poor and zinc-rich nature. The CZTSe films are p-type conductivity confirmed by a hot point probe method. Photoluminescence spectrum shows slightly asymmetric narrow bands with a maximum of intensity at 0.92 eV. The dependence of the photoluminescence on the excitation temperature reveals a decrease in the intensity of the photoluminescence bands. An absorption coefficient exceeding 10⁴ cm^?1 and the band gap energy about 0.87 eV of the studied films are determined by an absorption spectroscopy.     

Cu2ZnSnS4纳米颗粒及其薄膜的制备与表征

采用热注入法,在油胺(OLA)中合成出Cu2ZnSnS4(CZTS)纳米颗粒,并在玻璃衬底上制备了薄膜,研究了不同合成温度对纳米颗粒生成的影响.通过X射线衍射仪、拉曼光谱仪、透射电子显微镜、扫描电子显微镜、紫外可见分光光度计对所得纳米晶材料的结构与成分、颗粒大小与形貌、光吸收谱进行了测试分析.研究结果表明:采用热注入法的最佳合成温度在260℃左右,该温度下生成的多晶CZTS纳米颗粒尺寸约10 nm,分散性良好,光学禁带宽度约1.5 eV.     

Solvothermal synthesis of crystalline phase and shape controlled Sn(4+)-doped TiO2 nanocrystals: effects of reaction solvent

The Sn(4+)-doped TiO(2) nanocrystals with controlled crystalline phase and morphology had been successfully prepared through easily adjusting the solvent system from the peroxo-metal-complex precursor by solvothermal method. The Sn(4+)-doped TiO(2) nanocrystals were characterized by XRD, Raman, TEM, HRTEM, XPS, ICP-AES, BET, and UV-vis. The experimental results indicated that the Sn(4+)-doped TiO(2) nanocrystals prepared in the pure water or predominant water system trend to form rodlike rutile, whereas the cubic-shaped anatase Sn(4+)-doped TiO(2) nanocrystals can be obtained in the alcohol system. The growth mechanism and microstructure evolution of the Sn(4+)-doped TiO(2) nanocrystals prepared in the different solvent systems are discussed. The liquid-phase photocatalytic degradation of phenol was used as a model reaction to test the photocatalytic activity of the synthesized materials. It was found that sample Sn(4+)-doped TiO(2) prepared in 1-butanol showed the maximum photoactivity, which attributed to higher band gap, optimal crystalline phase and surface state modifications.     

Effect of reaction conditions on the morphology and optical properties of ZnO nanocrystals

We report a simple hydrothermal method at low temperature for synthesis of zinc oxide (ZnO) nanorods followed by ultrasonication. The samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), UV–Vis absorption spectrophotometer and photoluminescence (PL) spectroscopy. The XRD results shows the prepared ZnO nanocrystals are in wurtzite structure. TEM results indicate the growth of ZnO nanorods with increasing reaction stirring time and morphology also get affected after ultrasonication. PL studies also reveal the presence of defects considered as the main reason for the green emission in PL with increasing reaction time and blue shift in UV emission corresponds to reduction of tensile strain.     

Fabrication and luminescent enhancement of Eu3+-doped Y2O3@YOF core-shell nanocrystals

In this paper, a two-step synthesis method for preparing Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals is introduced. Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals were prepared by combining an autocombustion process with a low temperature solid state reaction. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and fluorescence decay were employed to characterize the prepared samples. The results of XRD, TEM and EDS indicated that the products prepared by this method were not a mixture of Y2O3:Eu3+ and YOF:Eu3+ nanocrystals, but Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals. Compared with Y2O3:Eu3+ nanocrystals, a 20% increment in luminescence intensity was observed in the Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals, thus suggesting that coating with a YOF:Eu3+-shell can efficiently block the nonradiative relaxation channels that are induced by surface defect states.     

Preparation of nanocrystalline NiO–MgO solid solution powders as catalyst for methane reforming with carbon dioxide: Effect of preparation conditions

A surfactant assisted co-precipitation method was employed for the preparation of nano crystalline NiO–MgO with high specific surface area. The effects of several process parameters such as refluxing time; refluxing temperature and calcination temperature were investigated on the structural properties of the powders. The prepared samples were characterized by X-ray diffraction (XRD), N₂ adsorption (BET); temperature programmed reduction (TPR), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. The obtained results showed that increase of refluxing time and temperature increased the specific surface area and decreased the crystallite size. The results revealed that the addition of surfactant has a significant effect on the synthesis of MgO nanocrystals and led to obtain a powder with high surface area. The powder prepared with a surfactant to metal molar ratio of 0.03 was employed as catalyst in methane reforming with carbon dioxide.