溶胶-凝胶法合成ZnO纳米材料及其抗菌性能研究

采用溶胶-凝胶法制备氧化锌纳米材料并考察了其抗菌性能.研究发现,通过调控醋酸锌-无水乙醇-氢氧化钠反应体系的反应温度、反应时间、反应物浓度以及反应体系中的水含量可以控制纳米ZnO的粒径分布;以金黄色葡萄球菌和大肠杆菌作为革兰氏阳性菌和革兰氏阴性菌的代表,用抑菌圈法考察了材料的抗菌性能,结果表明,溶胶-凝胶法合成的ZnO纳米材料抑菌效果明显优于相应的水热法产物和市售产品,且与其粒径分布密切相关;在实验条件下,ZnO材料对大肠杆菌和金黄色葡萄球菌的抑制性能随ZnO纳米材料的粒径增大在5nm左右出现一个极值,材料的粒径小于或大于5nm,其抗菌效果均变差.     

热蒸发沉积法制备多足状ZnO及其生长机理的研究

利用热蒸发沉积方法，使用高纯Zn粉为原料（ 〉99．99％），在常压下，成功制备了多针状的znO微结构。当沉积气氛为纯氧气时，多针ZnO单支的直径尺寸在2μm左右，通过调整Ar和O2的比例，发现当蒸发源温度为800℃，气体流量控制在Ar：O2=0．5L／min：0．1L／min的时候，所制备的多足状ZnO的单支直径减小为400nm,采用XRD和SEM对样品进行了表征，并对形成这种多针状ZnO的生长机理进行了详细的讨论。     

Low temperature aqueous chemical synthesis of CdS sensitized ZnO nanorods

Cadmium sulfide nanoparticles (CNPs) sensitized zinc oxide nanorod arrays (ZNRs) were synthesized in the two step deposition process at relatively low temperature. The vertically aligned ZNRs were grown on the conducting glass substrates (FTO) using aqueous chemical method, followed by the deposition of CNPs at 70 °C using chemical bath deposition (CBD) technique. The samples were characterized by optical absorption, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). Further, the photoelectrochemical (PEC) performance of ZNRs with and without CNPs sensitization was tested in Na₂S-NaOH-S and Na₂SO₄ electrolyte, respectively. When the CNPs are coated on the ZNRs, the optical absorption is enhanced and band edge is shifted towards visible region (525 nm) as compared with ZNRs (375 nm). The sample sensitized with CNPs shows higher photoelectrochemical (PEC) performance with maximum short circuit current of (I_sc) 2.60 mA/cm².     

纳米ZnO晶体的制备及其荧光性能研究

采用直接沉淀法，通过改变沉淀剂（氨水、NaOH）及反应时间制备纳米ZnO粒子，并通过扫描电子显微镜、荧光显微镜对所得产物的形貌及其荧光性能进行分析表征。结果显示：不同沉淀剂制备的ZnO纳米粒子的形貌和尺寸均不相同，用Zn（NO3）2和NH3．H2O反应可制得花状的纳米粒子，而用Zn（NO3）2和NaOH反应则会生成球状的纳米粒子，其尺寸分别为500和200nm左右；反应前期，反应时间主要影响粒子的尺寸，随反应时间的增加粒子的形貌也发生变化；与以NaOH为沉淀剂制备的纳米ZnO粒子相比，以氨水为沉淀剂制备的纳米ZnO粒子具有好的荧光性能。     

不同形貌纳米ZnO的合成及其光催化性能研究

以Zn(NO3)2·6H2O和NH4HCO3为原料,采用直接沉淀法制备了不同形貌和微观结构的纳米氧化锌。详细研究了反应终点pH值及沉淀前驱物的后处理方式等对粉体的晶体结构、形貌、粒径分布和团聚状况的影响。通过调节反应条件可分别获得网络状或颗粒状纳米氧化锌;光催化降解实验结果表明,网络状纳米氧化锌的光催化性能优于纳米颗粒状产物,而且该网络状和颗粒状纳米氧化锌的光催化活性均明显优于商品光催化剂P25。     

ZnO一维纳米材料的制备与表征

首先以乙醇为溶剂,乙酸锌为前驱体,油酸钠为表面修饰剂,采用溶液化学法,制得ZnO纳米粒子。以自制ZnO纳米粒子为基体,通过煅烧方法制备针状ZnO纳米线束。通过紫外-可见吸收光谱(UVVis)、荧光光谱(FL)、透射电子显微镜(TEM)、X射线衍射(XRD)和扫描电子显微镜(SEM)等方法对合成的样品进行表征。结果表明,所合成ZnO纳米粒子样品UV-Vis吸收光谱在355nm给出ZnO纳米粒子的特征吸收峰,FL光谱显示在400和550nm处产生荧光发射。ZnO纳米粒子尺寸约为5nm且粒径分布较窄。自制ZnO纳米粒子样品经500℃煅烧后可得到针状ZnO纳米线束。纳米线为六方晶系纤锌矿结构ZnO单晶纳米线,长度约为10μm,直径约为100nm,长径比约为100,且具有良好的紫外发光性能。     

氧化锌晶须的制备及生长机理研究

系统地介绍了氧化锌晶须的不同形态和制备方法(氧化法、液相法、微波辐射法、离子交换树脂法),阐述了氧化法制备氧化锌晶须的生长机理及应用前景.     

ZnO纳米带梳的制备及生长机理的研究

采用化学气相沉积(CVD)法成功制备出ZnO纳米带梳,实验过程不需要催化剂.X射线衍射仪(XRD)分析结果表明,ZnO纳米带梳为高度结晶的六方纤锌矿结构;利用扫描电子显微镜(SEM)观测,所制样品是由纳米带组成梳状形貌,纳米带梳的形成经过两个步骤:先通过VS机制形成微米带,而梳的齿通过自催化生长平行于(0001)极性面形成.对样品的光致荧光(PL)谱测量发现了位于～395nm和495nm处的室温光致发光峰.     

ZnO纳米棒水热法制备及其发光性能

采用水热法在玻璃基底上成功制备出了ZnO纳米棒.用x射线衍射仪(xRD)和扫描电子显微镜(SEM)对ZnO纳米棒的晶体结构和表面形貌进行了表征,初步探讨了ZnO纳米棒的生长机理;同时对ZnO纳米棒的光致发光性能进行测量,分析了水热温度和反应时间对ZnO纳米棒光致发光性能的影响.结果表明:ZnO纳米棒呈现六方纤锌矿结构,具有沿(002)晶面择优生长特征;随着水热反应温度的升高,ZnO纳米棒的发光强度逐渐增强;随着反应时间的延长,ZnO纳米棒发光强度在1～3 h内增强,而在3～10 h反而减弱.     

梳状氧化锌纳米材料的制备及结构、性能的表征

通过纯锌粉蒸发，在600-650℃无催化条件下成功制备了高质量的梳状ZnO纳米结构。通过扫描电镜（SEM）及高分辨透射电镜（HRTEM）观察，所制备的梳状ZnO纳米结构具有两种典型形貌，且皆为单晶结构，分析表明其生长由气-固生长机理控制。室温光致发光谱显示，梳状ZnO纳米结构在385nm附近形成紫外发射峰；在以495nm为中心的范围内，形成较宽的绿光发射峰。     

Folic acid mediated synthesis of hierarchical ZnO micro-flower with improved gas sensing properties

The microscale structure and size are extremely important factors for gas sensing materials. In this study, hierarchical flower-like ZnO architectures were synthesized by a biomolecular mediated route. The influence of various experiment parameters including reaction time, pH value, and reaction temperature on the formation of ZnO architectures was studied. When used as sensing material, this material possesses a higher sensing response towards ethanol and formaldehyde. Towards 100 ppm of ethanol and formaldehyde, the ZnO sensor can display remarkable sensing responses (R_a/R_g) of 13.6 and 16.5, respectively. These values are higher than or comparable to most of reported ZnO-based gas sensors. In addition, the sensors can show obvious sensing response to 5 ppm of ethanol and formaldehyde, indicating the lower limit of detection. It is proposed that the unique hierarchical microstructure contributes to the enhanced sensing performance.     

Direct synthesis of monodispersed ZnO nanoparticles in an aqueous solution

Monodispersed ZnO nanoparticles with mesopores were successfully prepared via a simple route through the transformation of Zn(NH₃)₄²⁺ precursor in the presence of sodium oleate and hydrazine at 80 °C with the pH of 8.5. Hydrazine and sodium oleate were used to control the size at 30-60 nm and to improve dispersion properties of ZnO nanoparticles. The samples were characterized by TEM, XRD, IR and TG-DTA, and the results suggest that the grains are composed of ZnO and a small quantity of oleate. The oleate plays an important role in preventing the ZnO nanoparticles from aggregating.     

Microfluidic synthesis of nanomaterials

An overview of the current information and analyses on the microfluidic synthesis of different types of nanomaterial, including metallic and silica nanoparticles and quantum dots, is presented. Control of particle size, size distribution, and crystal structure of nanomaterials are examined in terms of the special features of microfluidic reactors.     

Shed light on submerged DC arc discharge synthesis of low band gap gray Zn/ZnO nanoparticles: Formation and gradual oxidation mechanism

Synthesis of colloidal metal oxides with controllable size and morphology is burgeoning field of research in nanoscience. Low band gap gray Zn/ZnO colloidal nanoparticles were fabricated by plasma-liquid interaction of DC arc discharge in water. Scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy were employed for morphology, crystal structure and optical characterizations respectively. Optical emission spectroscopy was used to investigate the plasma properties during the synthesis and formation mechanism of nanoparticles. Nanoparticles with different size and shape were fabricated only by adjusting discharge current during synthesis without introducing any chemical agent. Electric discharge current was set to 20, 50, 100 and 150?A during synthesis. Estimated values of plasma excitation energies were 2.41, 2.66, 2.86 and 3.04?eV and diameter size of nanoparticles were 63, 42, 37 and 29?nm for these applied currents respectively. Synthesized nanoparticles were dark gray as prepared and became more transparent gradually getting white color finally. XRD and UV–vis results revealed that the oxidation process was time dependent. The colloidal nanoparticles composed of two metal and metal-oxide phase and white crystalline ZnO was achieved after complete oxidation process. These results provided a flexible and versatile method to synthesize metal oxide nanoparticles with controlled composition.     

Sol-gel synthesis,structural and enhanced photocatalytic performance of Al doped ZnO nanoparticles

In this research ZnO and Zn_1?x Al_xO (x = 1, 3, 5, 7% mol) nanoparticles were synthesized by sol-gel method. The effect of Al concentration on the structure, morphology, absorption spectra and photocatalytic properties investigated by using X-ray, TEM, EDS and UV–Vis spectrophotometer approaches. Hexagonal, spherical and rod-like structure was achieved as the dominant structure for undoped nanoparticles, low and high concentrations of doped Al, respectively. Photocatalytic activity of nanoparticles was measured by degradation of methyl orange as a pollutant under radiation of ultraviolet (UV). The experimental test results indicate that the best photocatalytic performance is at of 5% of Al. Furthermore, the doped ZnO nanoparticles have more activity in visible area compared with undoped nanoparticles. The absorption amount in this area increases by raising the Al concentrations. Furthermore, the band gap of the particles decreases from 3.22 eV to 2.93 eV by increasing Al percentage.     

Dendritic and epitaxial growths of ZnO particle-rod and rod-rod nanostructures with quasi-one-dimensional and two-dimensional configurations

Quasi-one-dimensional and two-dimensional ZnO nanostructures have been fabricated through thermal evaporation approach. The microstructures of the ZnO nanostructures have been studied using scanning electron microscopy and high-resolution electron microscopy. Quasi-one-dimensional ZnO nanostructures are formed by dendritic growths of ZnO nanoparticles from the stem nanorods surfaces, forming particle-rod nanostructures. While epitaxial growths of branch nanorods from the stem nanorods configure two-dimensional ZnO nanostructures. The epitaxial growth orientation relationship can be described as [2? 110]_R1 || [2? 110]_R2 and (0001) _R1 || (011?0)_R2. The growth mechanism of the quasi-one-dimensional and two-dimensional ZnO nanostructures has been discussed.     

ZnO纳米结构的CVD制备工艺及其应用

纳米结构的ZnO由于具有优异的光、电、磁、声等性能,已经成为光电、化学、催化、压电等领域中聚焦的研究热点之一.不同纳米结构的ZnO其制备方法不同,着重概述了采用化学气相沉积(CVD)工艺制备ZnO纳米材料,包括直接热分解、高温加热锌粉、碳热还原法以及金属有机气相沉积(MOCVD)4种方法,重点讨论了不同锌源和氧源对ZnO纳米结构的影响规律,并初步探讨了ZnO的VLS与VS生长机理,同时展望了ZnO在各领域中的最新应用.     

Sn掺杂ZnO纳米带的制备及其光致发光性能研究

采用热蒸发法制备了单晶Sn掺杂ZnO纳米带,其中Sn的掺杂含量约为5%(原子分数).X射线衍射(XRD)结果表明Sn掺杂ZnO纳米带为单相纤锌矿结构.X射线光电子能谱(XPS)表明样品中Sn的价态为4+.样品的室温光致发光谱(PL)在445.8nm处存在较强的蓝光发射峰,对其发光机制进行了分析.     

表面活性剂对ZnO纳米晶形貌的影响

采用低温水热法，通过未添加表面活性剂、添加CTAB和添加SDS三种方式成功制备了各种ZnO纳米晶。利用X射线衍射（XRD）、拉曼光谱及扫描电镜（SEM）等测试手段对ZnO纳米晶的晶体结构和表面形貌进行了表征。结果表明，所有ZnO纳米晶均为高质量的六方纤锌矿结构，并呈现不同的形态，如花形、卷心菜形等。详细讨论了在不同表面活性剂水热生长的条件下，ZnO纳米晶的生长机制。此外，对ZnO纳米晶的光致发光性能进行了测量，发现所有产物均具有相似的光发射峰位。