具有四角状棒-线结构纳米氧化锌的制备和性能

用气相氧化法合成出具有纳米棒-线结构的ZnO纳米材料.扫描电子显微镜(SEM)、透射电子显微镜(TEM)观察和X射线衍射谱(XRD)的分析表明:四角状ZnO纳米材料具有六方纤锌矿晶体结构,在棒-线纳米结构中,每个角的长度为1～2 μm,纳米棒的直径为100～200 nm,纳米线的直径约为30 nm.用气-固(VS)生长机制解释了棒-线纳米结构的形成.与ZnO大块材料不同,四角状ZnO纳米棒-纳米线材料在室温下具有～380 nm波长的紫外发射和～520 nm波长的绿光发射,其机理是晶体中杂质与结构缺陷少,以及与其纳米尺度相联系的量子限域效应.     

晶面择优取向ZnO纳米棒阵列膜的制备及其光催化活性研究

采用简单、低温的方法,在修饰过的Zn片上成功制备出具有高度取向的ZnO纳米棒阵列.用SEM、XRD和PL技术对制备出的ZnO纳米棒的结构和谱学特性进行了表征,并通过降解甲基橙溶液研究了其光催化活性.结果表明,ZnO纳米棒是六方钎锌矿晶,与基底垂直,具有沿(002)晶面择优生长的特征.统计结果显示,湿化学反应24h后90%以上的ZnO纳米棒直径为80～140nm,长度为4μm.在PL谱中观察到3个荧光发射带,中心波长分别位于386nm的紫带、524nm的绿带和450～500nm附近的蓝带.ZnO纳米棒的光催化反应为一级反应,表观速率常数与甲基橙的初始浓度有关.     

氧化锌纳米棒形貌对ZnO/Cu2O异质结太阳能电池光伏性能的影响

采用电化学沉积法制备了ZnO纳米棒,首先讨论了电化学沉积参数对氧化锌(ZnO)纳米棒形貌的影响,并对不同长度ZnO纳米棒的光吸收和反射等性质进行了研究.实验发现沉积时间是影响纳米棒长度、直径的重要因素,ZnO纳米棒的微观形貌对其光学性质有重要影响.然后以氧化锌纳米棒为n型材料,以氧化亚铜为p型材料,通过电化学沉积法构筑了ZnO/Cu2O异质结太阳能电池,并测试了其光伏性能,研究表明增长纳米棒阵列的长度使得开路电压、短路电流密度及光电转换效率等性能得到提升.最后,综合分析了氧化锌纳米棒形貌与所组装电池的性能之间的关系,发现调控氧化锌纳米棒的形貌是提高ZnO/Cu2O异质结太阳能电池光伏性能的有效途径.     

纳米氧化锌的制备及其光致发光性能研究

采用低温蒸发和气相输运方法,研制出ZnO的纳米棒－纳米钉、纳米钉类球状聚集体和具有钉状结构的纳米梳。利用透射电子显微镜和X射线衍射仪对其形貌与结构进行了表征,阐明了ZnO纳米结构的生长机理。用荧光光谱仪测量了退火前后纳米棒－纳米钉结构的光致发光谱,结果显示,在380nm处两者均存在近紫外峰,在500nm处出现绿色宽谱峰,而退火2h后近紫外发光峰窄而强,且发生了少许蓝移,此现象可归因于退火后的ZnO纳米结构具有较低的点缺陷浓度。     

脉冲磁控溅射制备硼掺杂氧化锌纳米薄膜的光学特性研究

采用脉冲磁控溅射法制备硼掺杂氧化锌（ZnO：B）纳米薄膜,研究了其结构和光学特性,经XRD分析,ZnO：B为多晶纳米薄膜,具有六方钎锌矿结构,薄膜沿着c轴取向择优生长。薄膜在可见光和近红外光谱区的透光性很好,其中在可见光区的平均透光率可达84％以上,而在近红外区的透光率随着波长增加而逐渐降低至45％。在可见光区,ZnO：B纳米薄膜的光学常数随波长的变化很小且数值基本趋于恒定,而在紫外区,光学常数随波长的变化很明显,并且在367nm和397nm附近存在两个紫外发光峰。     

水解锌制备Zn/ZnO纳米结构及其光学性能研究

利用滚压振动磨在干法室温条件下将金属锌制备成尺度约为3~5nm的锌量子点,并使产物与水蒸气在250℃进行化学反应,得到纳米氧化锌或纳米氧化锌与锌的混合物。分别利用能量发射谱仪(EDS)、透射电镜(TEM)对样品成分和形貌进行了表征。结果表明,250℃反应温度下得到的产物具有良好的分散性,其特征是棒状和片状结构共存,而且纳米棒具有显著的沿[011 1]晶向生长的趋势。室温下光致发光(PL)谱显示,在360nm和388nm处有双紫外发射峰,属于激子态发光,双紫外发射峰可能与掺杂能级有关;同时,在496nm处有蓝光发射峰,在515nm处有绿光发射峰,这两种发射属于表面缺陷态发光。对各种发光峰的发光机制进行了讨论。UV-Vis吸收光谱表明,产物在紫外区有很强的紫外吸收,吸收峰出现了蓝移现象,验证了Zn纳米量子点的掺杂形成掺杂能级,也与测得的可见光发射一致。     

表面活性剂辅助水热合成氧化锌纳米棒

以碱式碳酸锌为前驱体, 十六烷基三甲基溴化铵为表面活性剂, 在乙醇-水体系中水热反应制备了直径在10nm以下的氧化锌纳米棒. 用XRD、TEM、SAED等分析手段对制备的粉体进行了表征, 并对粉体的室温光致发光性能进行了测试. 结果表明, 合成的氧化锌纳米棒结晶良好, 沿[001]方向生长, 具有良好的近紫外发光性能. 同时对氧化锌纳米棒的生长机制进行了探讨.     

水热法制备掺铝氧化锌纳米棒阵列及其光学特性

采用水热法,在ZnO种子层上制备出不同Al掺杂量的ZnO纳米棒阵列薄膜,利用XRD、SEM、TEM、PL等检测手段对样品进行结构、形貌和发光性能分析.结果表明,纳米棒属于六方纤锌矿结构,具有垂直基底沿[002]方向生长的特征,PL谱上存在强的近紫外辐射峰.随着掺杂量的增加,纳米棒直径略有减小,近紫外辐射峰蓝移,强度先增加后减小,证明掺杂会形成非辐射中心,探讨了Al掺杂ZnO纳米棒阵列的发光机理.     

ZnO纳米棒的微波合成及Pt掺杂对其气敏性能的改善

以Zn(NO3)2·6H2O和NaOH为原料,CTAB为表面活性剂,微波加热到90℃,反应30min,成功制备了ZnO纳米棒.X射线衍射仪(XRD)和扫描电镜(SEM)结果表明,产物是六方纤锌矿结构ZnO纳米棒,长度为1～5μm,直径为50～100nm左右.对ZnO纳米棒进行了Pt掺杂,并对掺杂前后的气敏性能进行了对比...     

氧化锌纳米棒有序阵列的制备及表征

氧化锌是一种重要的化合物半导体,其低维结构在微电子器件领域具有潜在的应用前景.在温和的条件下利用软化学方法在沉积了单层ZnO颗粒膜的玻璃衬底上制备了直径为70～300nm,长约1μm的氧化锌纳米棒有序阵列,讨论了颗粒膜对阵列生长的作用以及水浴温度对晶体结构和形貌的影响.结果表明,产物为纤锌矿结构;ZnO颗粒膜为阵列的生长提供了分布均匀且固定的形核中心,对阵列的有序生长起诱导作用;随着反应温度的升高,阵列直径变小且排列更加有序,但过高的温度会抑制ZnO晶体内部的c轴择优取向作用.研究了ZnO阵列的光致发光特性,初步讨论了其发光机理.     

Low-temperature synthesis of ZnO nanorods using organic-inorganic composite as a seed layer

Well-aligned zinc oxide (ZnO) nanorods were synthesized using a low-temperature hydrothermal method employing a zinc/sodium dodecyl sulfate (Zn/SDS) composite as a seed layer. The results of X-ray diffraction measurements indicate that the Zn/SDS composite has a lamellar structure with an interlayer distance of 3.12 nm, which is shorter than that of the lamellar structure of SDS (3.82 nm) due to ion exchange between Zn and Na. The results of X-ray absorption fine structure analyses suggest that ZnO crystals start to grow after an induction period of 20-30 min. The length of nanorods and the aspect ratio of ZnO nanorods could be controlled by altering the molarity of ammonium and zinc nitrate in the growth solutions.     

Sonochemical method for the preparation of ZnO nanorods and trigonal-shaped ultrafine particles

ZnO nanorods and trigonal-shaped ZnO ultrafine particles were synthesized by sonochemical method through the decomposition of zinc acetate dihydrate in paraffin oil. ZnO nanorods and trigonal-shaped ZnO ultrafine particles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and UV–visible spectrophotometer. One strong UV emission peak at 390 nm was observed.     

Solvothermal synthesis of hexagonal ZnO nanorods and their photoluminescence properties

Pure hexagonal ZnO nanorods were synthesized by low-temperature (90 °C) solvothermal treatment of zinc acetate in 40-80 wt.% hydrazine hydrate aqueous solutions. The products were characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), selected area electron diffraction (SAED), and room temperature photoluminescence (RTPL) spectra. They show a strong UV emission at around 380 nm upon excitation at 360 nm using a Xe lamp at room temperature. The influence on the quality of the nanorods was investigated while the content of the solvent changed. The as-synthesized ZnO nanorods are promising materials for nanoscale optoelectronic devices due to their excellent UV emission properties.     

Optoelectronics behaviour of ZnO nanorods for UV detection

In this study ZnO nanorods have been synthesized by a chemical precipitation method. The room temperature UV–Vis absorption spectra of the ZnO nanorods indicated two absorption peaks in the UV region, one in the near UV region and the other attributed to the band gap of ZnO. The Photoluminescence spectra of ZnO nanorods show two emission bands, one ultraviolet emission band at 378 nm and the other in the defect related yellow emission band near 550 nm. The stimulated yellow luminescence of ZnO nanorods were affected by the synthesis time and annealing temperature. The same ZnO nanorods were deposited onto the ITO substrate to form a UV photoconductive detector. The ratio of the UV photogenerated current to dark current was as high as nine times under 3 V bias. Hence, these nanorods can be promising materials in the use of UV radiation detection.     

High-yield chemical synthesis of hexagonal ZnO nanoparticles and nanorods with excellent optical properties

Large yield and low temperature growth of nanostructures are key requirements for fulfilling the demand of large scale applications of nanomaterials. Here, we report a highly efficient chemical method to synthesize high quality hexagonal ZnO nanoparticle and nanorods utilizing the low temperature oxidation of metallic zinc powder in the presence of an appropriate catalyst. This one-step method has advantages such as low temperature (90 degrees C) and atmospheric pressure synthesis and a high yield (> 90%). Microstructure and optical properties of the as-synthesized ZnO nanoparticles are found to be identical or better than those of the commercial ZnO nanopower (Sigma-Aldrich). In particular, in comparison to the commercial nanopowder the as-grown ZnO nanorods and nanoparticles exhibit stronger UV absorption at 376 nm and intense UV photoluminescence emission at -382 nm, with negligible defect emission band. This method is suitable for large-scale production of nanosized ZnO and could be extended for the synthesis of other metal oxides.     

ZnO@CdS core–shell thin film: fabrication and enhancement of exciton life time by CdS nanoparticle

In the present study photoluminescence behavior of ZnO and ZnO@CdS core–shell nanorods film has been reported. ZnO nanorods were grown on the glass coated indium tin oxide (ITO) surface by seeding ZnO particle followed with nanorods growth. These nanorods were coated with CdS by chemical bath deposition techniques to have ZnO@CdS thin film and further annealed at 200 °C for their adherence to the ITO surface. The coating was characterized for surface morphology using SEM and optical behavior using UV–visible spectrophotometer. Energy dispersive X-ray (EDX) was used for compositional analysis and time resolve photoluminescence decay for excitons life time measurement. The absorption spectrum reveals that the absorption edge of ZnO@CdS core–shell heterostructure shifted to 480 nm in the visible region whereas ZnO nanorods have absorption maxima at 360 nm. The excitons lifetime of ZnO@CdS was found to be increased with the thickness of the CdS layer on ZnO nanorod. These ZnO@CdS core–shell nanostructures will be of great use in the field of photovoltaic cell and photocatalysis in a UV–visible region.     

Growth of well-aligned ZnO nanorods using auge catalyst by vapor phase transportation

Well-aligned ZnO nanorods have been achieved using new alloy (AuGe) catalyst. Zn powder was used as a source material and it was transported in a horizontal tube furnace onto an AuGe deposited Si substrates. The structural and optical properties of ZnO nanorods were characterized by scanning electron microscopy, high resolution X-ray diffraction, and photoluminescence. ZnO nanorods grown at 650 degrees C on 53 nm thick AuGe layer show uniform shape with the length of 8 +/- 0.5 microm and the diameter of 150 +/- 5 nm. Also, the tilting angle of ZnO nanorods (+/- 5.5 degrees) is confirmed by HRXRD. High structural quality of the nanorods is conformed by the photoluminescence measurement. All samples show strong UV emission without considerable deep level emission. However, weak deep level emission appears at high (700 degrees C) temperature due to the increase of oxygen desertion.     

Synthesis of Sn-doped ZnO nanorods and their photocatalytic properties

Sn-doped ZnO nanorods were fabricated by a hydrothermal route, and characterized by X-ray diffraction, field emission scanning electron microscope, UV-vis spectroscopy, Raman spectra, solid-state nuclear magnetic resonance (NMR) spectra, and room temperature photoluminescence spectroscopy. Solid-state NMR result confirms that Sn⁴⁺ was successfully incorporated into the crystal lattice of ZnO. Room temperature photoluminescence showed that all the as-synthesized products exhibited a weak UV emission (380 nm) and a strong visible emission (540 nm), but the intensities of the latter emission increased with increase in Sn concentration. The improvement of visible emission at 540 nm in the Sn-doped ZnO samples was suggested to be a result of the lattice defects increased by doping of Sn in zinc oxide. In addition, the photocatalytic studies indicated that Sn-doped ZnO nanorods are a kind of promising photocatalyst in remediation of water polluted by some chemically stable azo dyes.     

ZnO纳米棒Al掺杂和A1,N共掺杂的制备技术与光致发光性能

采用水热法首先合成了Al掺杂ZnO(AZO)纳米棒,在此基础上通过550℃的氨气氛中退火制备了Al,N共掺杂ZnO(ANZ())纳米棒.运用X射线衍射(XRD),场发射扫描电镜(FESEM),透射电子显微镜(TEM),X射线能谱(EDS)和光致发光(PL)对样品进行了表征与分析.结果表明,制备的AZO和ANZ()纳米棒...     

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.