ZnO/SAPO-34组装体的制备及发光性质研究

以微孔分子筛SAPO-34为主体，采用锌盐浸渍-灼烧的方法，在SAPO-34的菱沸石笼中制备出ZnO纳米粒子，并对不同温度下灼烧后得到的ZnO/SAPO-34组装体的发光性质进行了研究。由于SAPO-34菱沸石笼的尺寸所限，制备出来的ZnO粒子粒径小于1 nm。量子尺寸效应使得SAPO-34笼中的ZnO纳米粒子的荧光光谱在近紫外区的发射谱峰有明显的蓝移。     

CMC辅助纳米ZnO粒子的制备及表征

以离子型纤维素醚羧甲基纤维素(CMC)的水溶液为反应介质,制备[Zn4CO3(OH)6]CMC水凝胶,洗涤、干燥后经不同温度煅烧前驱物得到ZnO纳米粒子。通过XRD、SEM、TEM、TG-DSC及FT-IR等测试技术对产物的组成、粒径及形态进行表征,研究了CMC对前驱物及ZnO形态和尺寸的影响。结果表明,由于CMC加入对煅烧前驱物产生的空间位阻作用,所制得纳米ZnO粒子粒度分布均匀、分散性好、不易团聚、粒子的平均粒径<20 nm。利用UV-V is测试了纳米ZnO的光吸收性能,所得的纳米ZnO在200~400 nm具有较强的吸收性。     

ZnO纳米粒子多相催化n-C7H16-SO2气相光化学反应的研究

利用自制的ZnO纳米粒子和商品的ZnO粒子，研究了ZnO粒子多相催化n-C6H16- SO2的气相光化学反应。利用气相色谱－质谱联用仪（GC／MS）和气相色谱仪（GC ）对反应物n-C6H16和SO2以及主要气相产物3－庚酮进行了定量分析，考察了不同 条件下它们的降解和产生趋势，初步探讨了氧气和水蒸气对ZnO粒子多相催化n- C7H16-SO2气相光化学反应的影响，并对反应的一些现象作了描述及相应的说明。 结果表明，无论有无氧化存在，ZnO粒子均能够对n-C7H16-SO2的气相光化学反应起 一定的催化作用，但是有氧气的催化活性比无氧气的高。这可能说明了ZnO的光催 化作用主要与生成的活性氧物种（O^*)有关，同时光致空穴（h^+）也能够直接引 发氧化反应；虽然ZnO纳米粒子的光催化活性随着焙烧温度的升高而降低，但是均 比商品的高。而在模拟大气的条件下，ZnO纳米粒子对n-C7H16SO2的气相光化学反 应有很大的影响，大大地促进了n-C7H16和SO2的降解，这说明ZnO纳米粒子的存在 对大气中SO2－烃的气相光化学反应的影响是不容忽视的。此外，对ZnO粒子多相催 化n-C7H16-SO2气相光化学反应的机理进行了探讨。     

Pd/ZnO和Ag/ZnO复合纳米粒子的SPS和XPS研究

用焙烧前驱物碱式碳酸锌的方法制备了ZnO纳米粒子，采用光还原沉积贵金属的方法分别得到了质量分数为0.5％的Pd/ZnO和Ag/ZnO复合纳米粒子，并利用XRD、TEM、XPS和SPS等测试技术对样品进行表征.初步探讨了贵金属在ZnO纳米粒子表面形成原子簇的原因及沉积贵金属对ZnO纳米粒子表面光电压信号的影响.以光催化氧化气相正庚烷为模型反应，考察了沉积贵金属对ZnO纳米粒子光催化活性的影响，并探讨了光催化活性有所提高的内在原因.结果表明， ZnO纳米粒子沉积贵金属后，其表面光电压信号明显下降，而光催化活性却大大地提高，这说明可以通过表面光电压谱的测试来初步的评估纳米粒子的光催化活性，即粒子的表面光电压信号越弱，其光催化活性越高.     

超声辐射沉淀法纳米ZnO的制备与表征

以草酸盐为沉淀剂,采用超声辐射沉淀法制备出纳米ZnO粉体,并通过XRD、TG－DTA－DTG、IR和TEM等技术研究了纳米ZnO的合成过程及粉体性能。结果表明,将超声辐射引入了普通沉淀法,可显著提高粉体性能,所得纳米ZnO粒子外貌的球形,粒度分布均匀,分散性好,平均晶粒尺寸为26nm。     

高能Zn离子注入CaF2基质形成ZnO纳米粒子的机制、构型及电子结构

将高能Zn2+注入到CaF2介电基质中,在CaF2的表面下注入Zn2+浓度呈近似高斯分布,通过氧气氛后经热退火形成ZnO量子点.采用MaterialsStudio和Gaussian98W程序,结合实验结果计算分析了CaF2基质中ZnO纳米粒子的电子结构和光学性质.选取由4个ZnO原胞组成的超晶胞模型计算了ZnO纳米粒子的吸收光谱,理论结果与实验结果相符.对ZnO纳米粒子电子结构的研究结果表明,ZnO纳米粒子与CaF2基质的相互作用主要是ZnO表面的O与基质中Ca之间的作用,这种作用使ZnO纳米晶体的Fermi能级变窄,带隙相应减小;ZnO纳米粒子表面构型的变化对其本征吸收光谱没有影响,理论计算结果与实验值一致.     

纳米结构ZnO在TiO_2薄膜上的电化学沉积及其表征

在三电极体系中,以硝酸锌水溶液作为电解液,采用阴极还原电沉积法成功实现了一维纳米结构ZnO阵列在TiO2纳米粒子/ITO导电玻璃薄膜基底上的沉积,并通过XRD、SEM、EDS和PL光谱等方法对样品进行了表征.重点研究了薄膜基底、电解液浓度、沉积时间、六次亚甲基四胺(HMT)的引入对ZnO沉积及其发光性质的影响.结果显示:与ITO玻璃基底相比,ZnO更易于在TiO2纳米粒子薄膜上实现电化学沉积.ZnO属于六方晶系的铅锌矿结构,并且沿着c-轴方向表现出明显的择优化生长,以形成垂直于基底的ZnO纳米棒阵列.延长沉积时间、增加电解液浓度和引入一定量的HMT等均对ZnO的生长有促进作用,进而使其纳米棒的结晶度和取向程度提高,进而解释了所得的薄膜分别约在375和520nm处表现出ZnO的强而窄的带边紫外光发射峰和弱而宽的表面态绿光发射带.     

纳米氧化锌的粒度控制与表征

采用溶胶-凝胶法制备了粒度小于10nm的ZnO纳米颗粒,用沉淀法制备了粒度大于10 nm的ZnO纳米颗粒.讨论了颗粒粒度的控制因素,得到不同粒度的产品.采用TEM、XRD、BET、UV-Vis等检测手段对不同粒度的ZnO纳米颗粒进行表征.结果表明粒度小于10 nm的ZnO纳米颗粒,具有量子效应,随粒度减小,紫外可见光光谱蓝移;粒度大于10 nm的ZnO纳米颗粒,不具有量子效应,它们的禁带宽度与块体ZnO的禁带宽度相同,为3.2 eV,不同粒度的ZnO纳米颗粒紫外可见光光谱相同.     

用TiO2，ZnO及Fe2O3纳米粒子光催化氧化庚烷的反应

 制备了三种n－型半导体氧化物TiO2，ZnO和Fe2O3纳米粒子，用X射线衍射和N2吸附技术分别对它们的结构及比表面积进行了表征．考察了三种氧化物粒子对庚烷的气相光催化氧化反应的催化活性．研究表明，对于同种催化剂，随着焙烧温度的升高，催化剂的粒径增大，比表 面积减小，光催化活性下降．三种催化剂纳米粒子的光催化活性顺序为TiO2（锐钛矿）＞ZnO＞Fe2O3，金红石型TiO2粒子的催化活性低于ZnO粒子．结合能带理论探讨了三种催化剂光催化活性差异的原因．     

ZnO纳米棒阵列的同步法制备及其PL性能研究

在较低温度下，采用化学法在Zn片和玻璃片上同步制备了ZnO纳米棒阵列。利用XRD、FESEM和HRTEM对样品进行了表征，并且通过光致发光谱研究了阵列的光致发光(PL)性能。结果表明，ZnO纳米棒阵列较为致密、取向性较好。纳米棒为六方纤锌矿相，沿c轴生长，平均直径约为60 nm。同步法制备的2种ZnO纳米棒阵列均具有较好的紫外和橙红色发光性能，但发光特性却存在一定差异，这可能主要是由于2种阵列中纳米棒的缺陷含量不同所致。     

Electrical,optical and photocatalytic properties of Ti-loaded ZnO/ZnO and Ti-loaded ZnO nanospheres

Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles have been synthesized by sol–gel method and analyzed for photocatalyst application. The phase confirmation was analyzed by powder XRD and surface morphology with HR-SEM and EDAX spectrum. The particle size measured using HR-TEM and SAED pattern confirms the crystalline nature of Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles. The optical properties were studied with UV–visible diffuse reflectance spectra. The DRS of Ti-loaded ZnO/ZnO nanoparticles are similar to those of pristine ZnO nanoparticles. The KM plots show both the synthesized Ti-loaded ZnO/ZnO and Ti-loaded ZnO exhibit in UV-A region. The electric properties are studied with impedance analyzer, and the results show the charge-transfer resistance of Ti-loaded ZnO/ZnO is larger than that of Ti-loaded ZnO nanoparticles. The photocatalytic activity was studied with methylene blue dye and phenol degradation by Ti-loaded ZnO/ZnO, Ti-loaded ZnO, TiO₂ and ZnO nanoparticles. The photocatalytic activity of Ti-loaded ZnO/ZnO nanospheres is slightly higher than that of other nanoparticles, which shows that they have excellent application as photocatalyst.     

脉冲激光法连续制备高蓝光荧光性的修饰纳米ZnO乙醇溶胶

采用聚焦脉冲激光束轰击浸于含有水杨酸的无水乙醇流动相中的ZnO固体靶, 连续制备得到了强度高达1.12×105的蓝色荧光(440 nm)的水杨酸修饰纳米ZnO乙醇溶胶. 考察了修饰剂的种类、浓度、添加顺序和流动相流速对其荧光性能的影响. 透射电镜结果表明, 所制备的纳米ZnO粒径分布在15—30 nm.     

Preparation of ZnO nanoparticles in a reverse micellar system and their photoluminescence properties

ZnO nanoparticles with spherical morphology and narrow size distribution were obtained by calcination of Zn(OH)2 nanoparticles, which were prepared in a polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar system and incorporated into polyurea (PUA) via an in situ polymerization of hexamethylene diisocyanate (HDI). The resulting ZnO nanoparticles demonstrated a near-UV emission and a green emission, the intensity ratio of which depended on calcination conditions. For the nanoparticles studied, the calcination atmosphere influenced remarkably the photoluminescence properties such as intensity ratio of the near-UV emission to green emission, rather than the size, morphology, and crystallinity of the ZnO nanoparticles. The green emission decreased by calcination in O2 flow but increased by calcination in N2 flow, as compared with the case calcined in air flow. This finding suggests that the green emission is enhanced with the increase of the number of oxygen vacancies of the ZnO nanoparticles and thus the photoluminescence properties of the nanoparticles were successfully controlled by the calcination condition, without changing the size and morphology.     

Enhanced luminescence of SiO2:Eu3+ by energy transfer from ZnO nanoparticles

ZnO nanoparticles embedded into SiO(2) by an ex situ method were shown to result in stable green emission with a peak at 510 nm compared to the normal peak at 495 nm from micron-sized ZnO powders. Green emission from ZnO nanoparticles was completely suppressed when they were embedded in SiO2 doped with Eu3+. Instead, the f-f emissions from Eu3+ were enhanced 5-10 times by energy transfer from the embedded ZnO nanoparticles to Eu3+. The Eu3+ luminescence increased as the Eu3+ concentration increased from 1 vs 5 mole % (for 10 mole % ZnO). In addition, the intensity increased as the embedded ZnO nanoparticles concentration increased up to 10 mole % (for 5 mole % Eu3+). The effects of phonon mediated energy transfer, quenching by activator interactions between Eu3+ ions, and energy back-transfer from Eu3+ ions to ZnO nanoparticles were discussed.     

Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.     

球形Y2O2S∶Yb,Ho上转换粒子的合成及其尺寸相关的发光机制研究

采用改进的均匀沉淀法结合固-气硫化工艺制备了一系列Y2O2S∶Yb, Ho上转换粒子. 利用X射线晶体衍射(XRD)和透射电子显微镜(TEM)对粒子的结构和形貌进行了表征, 并通过上转换发光光谱(UCL)和红外光谱(FTIR)研究了粒子的上转换发光性质. XRD和TEM结果表明, 所制备的样品均为单一的六方相结构, 且所有粒子均呈单分散和尺寸均一的球形, 其尺寸分别为40, 80和200 nm. 根据发光强度和激发功率间的对数关系曲线发现, 随着粒子尺寸的降低, 蓝光发射由三光子吸收过程转变为双光子吸收过程; 而绿光和红光发射虽然一直保持双光子吸收过程, 但其对数曲线斜率均随粒子尺寸的降低而逐渐增大. 对该材料的粒子尺寸与上转换发光机制的关系进行了讨论.     

The Effects of Non-thermal Plasma on the Morphology of Ce-doped ZnO: Synthesis,Characterization and Photocatalytic Activity of Hierarchical Nanostructures

ZnO nanoparticles with and without 8 mol % Ce dopant were synthesized by precipitation method and the prepared samples were treated with various types of non-thermal plasma in order to study their effects on the morphology and photocatalytic activity of the samples. As-prepared Ce-doped ZnO has a hexagonal wurtzite structure and the crystal system was not changed by the plasma treatment. The morphology of Ce-doped ZnO was changed from spherical particle to flower and rod-like shapes by the plasma treatment. The particle size of the treated Ce-doped ZnO is smaller in comparison with that of untreated sample. The photodegradation of methylene blue by the plasma-treated Ce-doped ZnO in aqueous solution is higher than that of the untreated Ce-doped ZnO. The enhancement of the photocatalytic activity by the plasma-treated samples may come from the particle size reduction, enhancement in charge separation efficiency and increase of the surface area.     

Green biosynthesis and characterization of zinc oxide nanoparticles using Corymbia citriodora leaf extract and their photocatalytic activity

ABSTRACT

We reported a green and simple method for biosynthesizing zinc oxide nanoparticles (ZnO NPs) using Corymbia citriodora leaf extract as reducing and stabilizing agent. SEM, EDX, XRD, UV–VIS spectroscopy, Raman spectroscopy and TGA have been used for characterizing the biosynthesized ZnO NPs. The results indicating the ZnO NPs synthesized by C. citriodora leaf extract have high purity and the average size is 64?nm. The photocatalytic activity of the ZnO NPs has been investigated by degradation methylene blue under visible light irradiation. Due to the smaller size, the biosynthesized ZnO NPs showed an excellent photocatalytic performance.     

焙烧温度对ZnO粉体结晶及光学性能的影响

以草酸铵和醋酸锌为原料,采用直接沉淀法制备ZnO粉体,考察了焙烧温度对粉体结晶和光学性能的影响。 采用热重分析（TGA-DTA）、X射线衍射、紫外-可见漫反射（UV-Vis）、荧光分光光度计（FS）和扫描电子显微镜（SEM）等方法对样品进行了分析。 结果表明,制备的前驱物为C2O4Zn·2H2O,最低焙烧温度400 ℃,随着焙烧温度的提高,粉体结晶度提高,一次粒径增大;600 ℃焙烧后有较强紫外发光峰,粉体由200 nm的粒子排列成层叠状;900 ℃焙烧后有较强可见发光峰,粉体粒子大于500 nm,团聚严重;粉体有较强的紫外吸收,吸收峰有蓝移。     

基于介孔纳米粒子模板合成兼有荧光和近红外发光的稀土核-壳结构纳米材料

利用单分散性良好介孔SiO2纳米粒子为模板,选择Y2O3为基底,同时掺杂可见区红光中心Eu3+和近红外区Er3+(1.54 μm)发光中心,成功制备特殊结构的核壳多功能发光纳米材料. 光谱测试表明这种核壳材料同时具有可见区发光和近红外发光的双重性质. 表明Y2O3可作为红光Eu和近红外发光Er的良好基底材料. 该方法可以大大降低纳米发光材料中稀土元素的使用量,降低发光材料的成本,并且该核壳结构材料密度相对较低,易于分散在有机溶剂或者水中,在药物释放和多功能生物标记等方面有着潜在的应用价值.