ZnO纳米棒的绿色合成及光催化性能研究

以Zn(Ac)2·2H2O和NaOH为反应物,以离子液体1-十二烷基-3-甲基咪唑四氟硼酸盐[C12mim][BF4]水溶液为反应介质,80℃下制得ZnO纳米棒。采用透射电子显微镜(TEM)、X射线衍射(XRD)和紫外可见吸收光谱(UVVis absorption spectra)对纳米ZnO的形貌和结构进行了表征,以有机染料亚甲基蓝溶液为光催化反应模型降解物,考察纳米ZnO的光催化性能。结果表明,制备出的纳米氧化锌呈棒状,宽约10nm,长约160nm,为六方纤锌矿结构。紫外灯照射120min后,对亚甲基蓝溶液的降解率可达到86.3%。     

纳米针状ZnO的绿色合成及光催化性能研究

以Zn(Ac)2·2H2O和NaOH为反应物,以离子液体1-苄基-3-甲基咪唑四氟硼酸盐[Bzmim][BF4]水溶液为反应介质,在80℃制得纳米针状ZnO。采用扫描电子显微镜(SEM)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-Vis absorption spectra)对纳米ZnO的形貌和结构进行了表征,以有机染料亚甲基蓝溶液为光催化反应模型降解物,考察纳米ZnO的光催化性能。结果表明:制备出的纳米ZnO呈针状,宽约25nm,长约220nm,为六方纤锌矿结构。紫外灯照射180min后,对亚甲基蓝溶液的降解率可达到97.1%。     

分级介孔结构组成的ZnO微球及光催化性能

以硝酸锌、脲素及酒石酸为反应物, 采用水热法制备碱式碳酸锌前驱体微球, 通过煅烧前驱体制备了介孔氧化锌微球。通过扫描电子显微镜(SEM)可以观察到, 氧化锌微球的直径约为2~4 μm, 由大量厚度约为10 nm的介孔纳米片组装而成。X 射线衍射(XRD)和透射电镜(TEM)结果表明: ZnO微球为六方纤锌矿结构, 并结晶较好。比表面积测试(BET)表明ZnO微球为介孔材料, 孔径为20~50 nm, ZnO微球比表面积约为29.8 m²/g。以亚甲基蓝为目标降解物, 对介孔氧化锌微球进行了光催化降解实验。实验结果表明, 所合成的介孔ZnO微球对亚甲基蓝的光催化性能较好。     

纳米ZnO中Al的掺杂及其在水溶液中光催化性能的研究

分别用热物理法制备ZnO、掺Al/Zno和光化学反应沉积制备掺Al/ZnO的纳米粉体材料,采用XRD,TEM等手段研究了ZnO超微粒子结构与形貌.在Al掺杂ZnO纳米晶的水相体系中,通过吸光度、脱色率的测定证实了Al掺杂有效的改善了ZnO对亚甲基蓝(MB)的光催化降解性能.Al掺杂ZnO纳米晶较普通氧化锌有更好的光催化活性.效果最好的是热物理法掺Al/ZnO对亚甲基蓝的降解.     

Ce掺杂氧化锌的制备及应用研究

以醋酸锌和硝酸铈为原料,采用水热法制备氧化锌(ZnO)纳米棒和铈(Ce)掺杂的Ce-ZnO复合材料。并对样品的物理和光学性能进行了表征。以亚甲基蓝溶液为模拟废水,研究了制得的ZnO复合材料的紫外光催化脱色效能。结果表明,在Ce用量为1.5%(摩尔分数),紫外光照时间为50min条件下,光催化性能最好,Ce-ZnO对100mL浓度为10mg/L的亚甲基蓝(MB)溶液的降解率达到98.6%,经过4次循环,对MB的降解率仍达94.1%,说明材料的光催化稳定性较好。     

静电纺丝制备树皮状ZnO纳米纤维及其光催化降解性能研究

采用静电纺丝制备的一维氧化锌(ZnO)纳米纤维是一种常见的可用于光催化降解有机染料和重金属离子污染物的半导体光催化剂。然而已报道的纳米纤维表面较为光滑，光催化能力有待进一步提高。本研究以硝酸锌为锌源，乙醇和N,N-二甲基甲酰胺作为混合溶剂，利用静电纺丝和高温煅烧合成了表面和内部同时具有丰富孔洞的树皮状ZnO纳米纤维，并研究了其对亚甲基蓝和Cr(Ⅵ)的光催化降解性能。通过调节纺丝液中锌源的浓度，得到了不同结构的ZnO光催化剂。X射线衍射仪、扫描和透射电子显微镜测试结果表明，所制备的ZnO纳米纤维高度结晶，纤维表面均匀分布有片状结构。光催化测试表明，经过3h紫外光照射后，树皮状ZnO纳米纤维对亚甲基蓝和Cr(Ⅵ)的降解效率分别达93.6%和63.4%。     

复合纳米ZnO-SnO2粉体的电合成及光催化性能的研究

采用改进的电化学法制备了ZnO-SnO2纳米复合氧化物粉体,通过XRD、FT-IR、TEM等测试手段,对产物的物相组成、粒径大小、形貌等进行了表征;并考察了该纳米复合粉体的光催化活性.结果表明,得到的产物(氧化锌与氧化锡的复合物)颗粒分布均匀、平均粒径约为30～50 nm;该复合氧化物对甲基橙及亚甲基蓝溶液的光催化降解明显优于单纯的ZnO或SnO2;前驱体的焙烧温度以及ZnO和SnO2的复合摩尔比对ZnO-SnO2的光催化活性有较大的影响.     

氧化锌/氧化镁纳米复合材料的制备及其光催化性能研究

采用微波辅助共沉淀法制备了纳米氧化锌/氧化镁(ZnO/MgO)光催化剂,并对催化剂样品进行了X射线衍射、透射电镜、红外光谱以及紫外-可见吸收光谱等表征。以亚甲基蓝(MB)为目标降解物对不同锌镁比的ZnO/MgO催化剂样品及相同方法下合成的ZnO及MgO进行光催化降解实验。结果表明:合成的纳米ZnO/MgO光催化剂由立方相的ZnO和非晶相的MgO组成,其尺寸均匀,在40nm左右,并在紫外区域吸收性能良好。光催化降解MB实验表明,锌镁比为2∶1时ZnO/MgO催化剂的光催化性能最佳。     

核壳纳米复合材料的光催化和抑菌性能研究

通过溶胶-凝胶法制备了银(Ag)@氧化锌(ZnO)纳米复合材料(Ag@ZnO),并采用激光粒度分布仪(DLS)、透射电子显微镜(TEM)、X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见分光光度计(UV-Vis)和热重分析仪(TGA)等仪器设备对制得的样品的形貌、晶型、热稳定性等进行了测试。结果表明:Ag@ZnO纳米复合材料呈现出良好的复合结构,粒径约50nm,具有良好的热稳定性能。研究了Ag@ZnO纳米复合材料对亚甲基蓝的光催化性能和对大肠杆菌等生物细菌的抑制性能。Ag@ZnO纳米复合微粒对亚甲基蓝溶液具有良好的光催化降解性能,降解率达到85%;对大肠杆菌具有很好的抑制性能。     

环境友好型塑料用改性ZnO添加剂的光催化性能研究

以纳米ZnO和AgNO3溶液为原料,采用掺杂的方法制备了改性的塑料用ZnO添加剂,通过其光催化降解亚甲基蓝的效果评价了样品的光催化性能。实验结果表明,当银的掺杂量为2.8%,光催化剂添加浓度是0.8g/L时,此时Ag/ZnO复合粉体对亚甲基蓝的光催化降解效果最好。制备的Ag/ZnO复合粉体在紫外光区和可见光区都有较强的吸收,且吸收峰波长和Ag与纳米ZnO相比都出现了一定程度的红移。掺杂银显著提高了纳米ZnO的光催化性能     

聚醋酸乙烯酯/纳米ZnO颗粒复合材料的等离子聚合及其光学性能

采用等离子镀膜方法在纳米ZnO颗粒表面沉积一层有机薄膜,制备出聚合物/ZnO复合材料.用高分辨透射电子显微镜(HRTEM)、傅立叶变换红外光谱(FTIR)、光致发光光谱(PL)和紫外-可见吸收光谱(UV-Vi8)对其形貌、结构和性能进行表征,研究了聚合物/ZnO复合材料的光学性能以及聚合物与纳米ZnO颗粒的结合强度.结...     

Novel and simple synthesis of ZnO nanospheres through decomposing zinc borate nanoplatelets

Spherical zinc oxide (ZnO) nanoparticles had been successfully synthesized through decomposing zinc borate nanoplatelets at high temperature. The resulted ZnO nanospheres were characterized by X-ray diffraction (XRD), which indicated that ZnO had the hexagonal structure. Field-emission-scanning electron micrographs (SEM) revealed that ZnO nanoparticles had perfect spherical shape with narrow size distribution (average diameters 50 nm). These nanoparticles showed a broad emission band centered at 438 nm using an excitation wave of 325 nm at room temperature. Moreover, the sample was characterized by N₂ adsorption-desorption and the pore size distribution showed a sharp peak at 3.1 nm.     

Room temperature ferromagnetism in Tb-doped ZnO dilute magnetic semiconducting nanoparticles

Pure and Tb-doped ZnO nanoparticles have been synthesized by chemical co-precipitation method. The transmission electron microscopy study reveals the spherical morphology of synthesized nanoparticles with average particle size 14–18 nm. The effect of Tb-doping on structural, optical and magnetic properties has been studied. X-ray diffraction shows that pure and Tb-ZnO nanoparticles exhibit wurtzite structure having hexagonal phase with primitive unit cell. It further reveals that there is no effect of Tb-doping on the X-ray diffraction pattern up to 2 % doping, however, higher doping concentration result in accumulation of Tb on ZnO surface. Photoluminescence spectra reveal that the doping Tb in ZnO changes crystallographic structure generating non-radiative oxygen vacancies. Three emission peaks located around 423, 485 and 515 nm has been observed. Pure ZnO nanoparticles show diamagnetic character, however, Tb-doped ZnO nanoparticles exhibit room temperature ferromagnetism. The correlation between defects generated upon Tb-doping to the observed ferromagnetism, in the synthesized nanoparticles, has been reported.     

ZnO nanoparticles embedded in sapphire fabricated by ion implantation and annealing

ZnO nanoparticles were fabricated in sapphire (α-Al(2)O(3) single crystal) by Zn ion implantation (48?keV) at an ion fluence of 1 × 10(17)?cm(-2) and subsequent thermal annealing in a flowing oxygen atmosphere. Transmission electron microscopy (TEM) analysis revealed that metallic Zn nanoparticles of 3-10?nm in dimensions formed in the as-implanted sample and that ZnO nanoparticles of 10-12?nm in dimensions formed after annealing at 600?°C. A broad absorption band, peaked at 280?nm, appeared in the as-implanted crystal, due to surface plasma resonance (SPR) absorption of metallic Zn nanoparticles. After annealing at 600?°C, ZnO nanoparticles resulted in an exciton absorption peak at 360?nm. The photoluminescence (PL) of the as-implanted sample was very weak when using a He-Cd 325?nm line as the excitation source. However, two emission peaks appeared in the PL spectrum of ZnO nanopraticles, i.e., one ultraviolet (UV) peak at 370?nm and the other a green peak at 500?nm. The emission at 500?nm is stronger and has potential applications in green/blue light-emitting devices.     

Small angle neutron scattering and photoluminescence property of wet chemistry process synthesised ZnO nanoparticles

We report the synthesis of zinc oxide (ZnO) nanoparticles from aqueous solution at 25°C and subsequent heating of the solution at 115°C by the suitable selection of the solution chemistry and the control of the alkaline conditions. The structure of the synthesised ZnO particles was studied by X-ray diffraction (XRD), confirming the formation of Wurtzite structure. The optical property of synthesised ZnO nanoparticles is investigated through room temperature photoluminescence (PL) measurement. The PL of ZnO nanoparticles shows a strong UV emission band at approximately 385 nm, a blue–green band at approximately 473 nm and a very weak green band at approximately 554 nm, although polydispersity of the sample shows no presence on the PL spectrum. Small angle neutron scattering is used to determine the size and the size distribution of ZnO nanoparticles. The SANS data analysis and model fitting predict the size as about 18–20 nm, which is closely matched with XRD and transmission electron microscopy results with Gaussian distribution.     

基于PEG修饰的ZnO量子点光学特性研究

采用溶胶-凝胶法制备了ZnO量子点, 并采用有机高分子试剂PEG(聚乙二醇, M_w=2000)对其表面进行修饰。借助X射线衍射分析、傅立叶红外光谱、光致发光谱和透射显微镜等测试方法, 研究了PEG表面修饰对ZnO量子点结构和光学性能的影响规律。研究表明, 混合加入的PEG聚合物能够成功地包覆在ZnO量子点表面, 但没有改变量子点的晶体结构, 经PEG表面修饰后的ZnO量子点尺寸变小, 稳定性增强, 分散更均匀。同时经PEG修饰的ZnO量子点在400~500 nm波长区域缺陷态发射峰明显减弱, 表明采用PEG来改善ZnO量子点表面缺陷结构具有良好效果。     

ZnO and conjugated polymer bulk heterojunction solar cells containing ZnO nanorod photoanode

Hybrid solar cells based on poly(3-hexylthiophene) (P3HT) and ZnO nanoparticle bulk heterojunctions (BHJ) combined with ZnO nanorod arrays were fabricated and analyzed. The dispersion of ZnO nanoparticles in P3HT is assisted by dye molecules, which function as a surface modifier for ZnO nanoparticles to improve compatibility between ZnO nanoparticles and P3HT. Compared to the ZnO nanorod/P3HT devices, the optimized cells with the ZnO nanoparticles dispersed in P3HT can significantly increase the short-circuit current and the overall power conversion efficiency from 1.36 mA cm(-2) to 2.51 mA cm(-2) and from 0.18% to 0.45% with 625 nm long ZnO nanorod arrays, respectively. The novel scheme of using the light-absorbing dye molecules both as light absorber and as surfactant for ZnO nanoparticles presents a facile route towards forming bulk heterojunction hybrid solar cells based on semiconducting nanomaterials and conjugated polymers.     

Preparation and characterization of ZnO/ZnS core/shell nanocomposites through a simple chemical method

In this paper, we reported the preparation of ZnO/ZnS core/shell nanocomposites by sulfidation of ZnO nanostructures via a simple hydrothermal method. The precursors of bare ZnO nanoparticles and ZnO nanorods were synthesized by a surfactant-assisted hydrothermal growth. The structural, morphological, and element compositional analysis of bare ZnO nanostructures and ZnO/ZnS core/shell nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy techniques. The XRD results indicated that the phase of bare ZnO nanoparticles and ZnO nanorods was wurtzite structure, and the phase of coated ZnS nanoparticles on the surface of bare ZnO nanostructures was sphalerite structure with the size of about 8 nm. Photoluminescence measurement was carried out, and the PL spectra of ZnO/ZnS core/shell nanocomposites revealed an enhanced UV emission and a passivated orange emission compared to that of bare ZnO nanostructures. In addition, the growth mechanism of ZnO/ZnS core/shell nanostructures through hydrothermal method was preliminarily discussed.     

Study of the properties of undoped and fluorine doped zinc oxide nanoparticles

ZnO and ZnO:F nanoparticles were successfully prepared by precipitation in the presence of oxalic acid. This procedure yields ZnO and ZnO:F nano-arrangements of different lengths consisting of chains of quasi-spherical nanoparticles of ∼ 30 nm in size. Only the wurtzite ZnO structure was detected for both undoped and fluorine doped ZnO nanoparticles. By absorption and photoluminescence measurements, a diminishing of singly ionized oxygen vacancies was detected when fluorine is present in the nanoparticles; while a blue shift of the exciton absorption was observed. Additionally, by NIR reflectance measurements, the creation of free carriers by the fluorine doping of ZnO nanoparticles was observed.     

Chemical Synthesis of ZnO Nanocrystals

A new chemical process to synthesize pure ZnO nanocrystal colloidal for bioimaging applications is reported. Zinc acetate dihydrate was dissolved and refluxed in a methanol solution at a low temperature (68degC) and ambient environment. Biocompatible surface capping agents were introduced to the synthesis process to control the particle nucleation and growth and, therefore, the particle size and its surface chemistry. Five types of capping agents were investigated for their effectiveness in limiting the particle growth. Three capping agents-3-amino- propyl trimethoxysilane (Am), tetraethyl orthosilicate (TEOS), and mercaptosuccinic acid (Ms)-were found effective in capping the ZnO nanoparticles and limiting the growth of the particles, while the other two-3-mercaptopropyl trimethoxysilane (Mp) and polyvinylpyrrolidone (Pv)-caused agglomeration or forming large clusters in the solutions. Particles synthesized were in the size range of 10-30 nm after capping, and grew to 60 nm and 100 nm in 3 weeks and 6 weeks respectively during storage at ambient conditions. Refluxing time was found to affect only the first precipitation time. Washing by ethanol and slow drying were found critical in converting Zn(OH)₂ into ZnO. XRD analyses revealed forming of single phase ZnO Wurzite (P63mc) structure. TEM analysis determined the single crystal size of 6 nm. Photo- luminescence (PL) spectra showed high intensity in UV emission and low intensity in the visible emission, which imply a good surface morphology of the ZnO nanoparticles with few surface defects. Optical absorption spectra indicated absorption at the wavelength of 380 nm from the uncapped ZnO, corresponding to the bandgap of bulk ZnO. The capped ZnO absorbed at a shorter wavelength (350 nm) indicating a much smaller particle size. Capping effectiveness of each agent is discussed through possible capping mechanisms and chemical reactions.