Zn/纳米棒阵列ZnO/聚噻吩复合电极的制备及光电化学性质

使用简单的水热法在锌片上生长ZnO纳米棒阵列,并用电化学共聚制备了ZnO纳米棒阵列与聚噻吩(Zn/ZnO/PTH)复合膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)等手段对ZnO的结构和形貌进行表征,XRD结果表明产物为六方纤锌矿型ZnO。SEM结果表明,在垂直锌片方向生长了包括纳米棒、纳米片、纳米线的表面光滑的ZnO纳米阵列,其中以纳米棒为主,其直径为30～100nm,长度1μm。用光电流作用谱、光电流-电势图研究了Zn/ZnO/PTH电极的光电转换性质。结果表明,PTH修饰ZnO/Zn电极可使光电流产生波长发生明显红移,使其光电转换效率提高了4倍,填充因子FF=33%,光电转换效率η=1.25%。     

ZnO:Cd纳米棒的制备及其光催化降解性能研究

采用水热法制备了ZnO和不同Cd掺杂浓度的ZnO:Cd纳米棒。通过x射线衍射仪、扫描电子显微镜、紫外-可见-近红外分光光度计和拉曼光谱对ZnO:Cd纳米棒的结构和光学特性进行了系统研究。结果显示,样品为一维纳米棒结构,Cd的掺杂可以减小ZnO纳米棒的晶粒尺寸和光学带隙。利用分光光度计检测ZnO:Cd纳米棒对偶氮结构染料(甲基橙溶液)的光催化降解效率,结果表明Cd掺杂可以改善ZnO的光催化性能,掺杂浓度为16%时ZnO:Cd纳米棒对甲基橙溶液的光催化降解效率最高。     

Zn0.98Nd0.02O室温拉曼特性和伏安特性

通过固相反应工艺制备了Zn0.98Nd0.02O纳米颗粒,射频磁控溅射技术在Si(111)衬底上制备了Zn0.98Nd0.02O薄膜。应用XRD、AFM以及拉曼光谱等手段,分析了Zn0.98Nd0.02O纳米颗粒与薄膜的结构,并测试了Zn0.98Nd0.02O薄膜的室温伏安特性。表明Nd掺杂没有改变ZnO纤锌矿结构,Zn0.98Nd0.02O颗粒为纳米多晶粉末态,其薄膜为沿(100)、(101)方向生长的纳米多晶结构,表面形貌粗糙。拉曼光谱分析表明,Zn0.98Nd0.02O颗粒的局部应力增大,晶格畸变缺陷增加,缺陷态比较复杂,导致拉曼峰发生频移。Zn0.98Nd0.02O薄膜的室温I-V曲线表明了Zn0.98Nd0.02O薄膜的非线性导电特性。其非线性导电特性源于,薄膜中的载流子受外加电场在薄膜中所产生热激发进入导带导电,环境光中能量高于ZnO带隙的光子引起的光电导效应,以及薄膜中纳米粒子间的隧穿导电。在光辐照作用下,提高了薄膜内浅施主缺陷浓度,降低了薄膜的表面电阻率,增强了Zn0.98Nd0.02O薄膜的导电能力。     

膨胀石墨/纳米氧化锌/锌复合电极材料的超级电容器性能

以膨胀石墨为原料,与滚压振动磨预处理得到的纳米锌粉混合,超声分散24h制备膨胀石墨-纳米氧化锌及锌的复合电极材料(EG/ZnO/Zn)。采用X射线衍射仪(XRD)、场发射扫描电子显微(SEM)、场发射透射电子显微镜(TEM)、拉曼光谱分析仪(Raman),对材料的微观结构及成分表征。结果表明,复合材料中含锌和氧化锌,纳米锌粉颗粒和氧化锌纳米棒在膨胀石墨表面和层间分散良好,其中氧化锌纳米棒呈现出六方晶系纤锌矿结构,其直径大约为20nm。利用电化学循环伏安和恒电流充放电对材料进行电化学电容性能测试,表明经处理的复合电极材料在0.1A/g的电流密度下有明显的赝电容特性,比电容达147F/g,其赝电容来源不只是欠电位沉积的化学吸附,还有氧化还原反应。     

晶格空位ZnO纳米棒的制备及其在镍锌电池中的应用

作为绿色、高功率密度的二次电池, 镍锌电池的应用往往受限于负极材料性能的不足。本工作以乌洛托品(HMT)为模板剂, 通过溶胶-凝胶法合成与热退火处理制备了高性能ZnO纳米棒。透射电子显微镜(TEM)、X射线衍射(XRD)和红外光谱(FT-IR)数据分别揭示了ZnO纳米棒的微观形貌、晶型结构和表面官能团。X射线光电子能谱(XPS)和电子顺磁共振(EPR)结果表明ZnO纳米棒中存在表层碳和晶格空位。Tafel曲线和电化学阻抗等测试表明: 与ZnO商品相比, ZnO纳米棒电极的腐蚀电流和电荷转移电阻分别降低了40%和62%。进一步研究发现, ZnO纳米棒构筑的镍锌电池具有更好的循环性能, 在1 A·g^-1下循环100圈后, ZnO纳米棒的容量保持率为92%, 显著优于市售的ZnO粉末(32%)。     

纳/微蒲公英状氧化锌材料的制备

采用溶剂热法,以Zn粉为锌源,通过柯肯特尔效应制备出由单晶ZnO纳米棒组成的三维蒲公英状的氧化锌纳米结构.通过XRD、SEM、RDS、SEAD、TEM和HRTEM等方法对样品的组成,结构和形貌进行了研究.该方法可作为一种新的大规模制备纳/微ZnO纳米材料而被广泛应用.     

ZnO纳米团簇与CdSe纳米棒复合膜的光电化学性能研究

用水热法合成了粒径均匀、分散良好的花状ZnO纳米团簇和CdSe纳米棒.讨论了ITO/ZnO/CdSe复合膜电极光电性能的影响因素,对比研究了ITO/ZnO纳米团簇及ITO/CdSe纳米棒膜电极的光电化学性能,实验表明:复合膜电极拓展了在长波方向的光吸收,提高了光电转换效率;当ZnO与CdSe复合摩尔比为1∶3时,ITO/ZnO/CdSe纳米复合膜电极在本实验中得到最高光电转换效率(IPCE)25.27%,远远高于单一ITO/ZnO花状纳米团簇膜电极和ITO/CdSe纳米棒膜电极.     

基于氧化铝模板的有序ZnO纳米棒的合成及光学特性研究

利用高度有序的多孔氧化铝膜作为模板,使用简单的热蒸发Zn粉的方法,成功地制备出高度有序的ZnO纳米棒束,该方法克服了制备有序纳米结构通常需要的催化剂或复杂的合成过程.利用扫描电镜、透射电镜和X射线衍射研究了样品的形貌及其结构特性,其结果表明模板表面所制备的ZnO纳米棒具有更好的有序度和结晶质量,从而推断出模板表面有序ZnO纳米棒的形成应该同模板表面局域化负电荷的存在有关.同Si基片上所形成无序纳米棒的光致发光谱相比,模板表面所形成的有序ZnO纳米棒束具有更强的紫外峰,表明有序的ZnO纳米棒具有更好的结晶质量和光学特性.     

ZnO纳米棒/石墨烯异质结构的应用研究进展

ZnO纳米棒具有优异的光学性质,石墨烯具有优良的电学性质并且可变形,制备出高质量ZnO纳米棒/石墨烯异质结构能够发挥两者协同效应,有望在高性能光电子器件中实现重要应用。综述了近几年来国内外关于ZnO纳米棒/石墨烯异质结构的最新研究进展,重点包括该结构的各种制备技术及特点,该结构在发光器件、太阳能电池器件、光电探测器以及光催化剂等方面的应用研究进展,最后展望了其未来发展趋势和研究重点。     

控制O2流量生长结状 ZnO微纳米棒及其特性研究

采用热蒸发法以锌粉和二水醋酸锌作为源材料在Si（111）衬底上制备了高密度的ZnO微纳米棒，制得的每根ZnO棒明显分为直径不同的四段．利用X射线衍射、扫描电镜、透射电镜、拉曼光谱和光致发光谱等测试手段对制备的样品进行了形貌、结构和光学性能的分析，结果表明制备的ZnO棒晶体质量良好，仅存在很少量的缺陷.通过讨论该结构的生长机理，发现O2分压对制备的ZnO微纳米棒的形貌有显著的影响，调节O2流量可控制ZnO纳米结构的形貌．     

Effect of Zn2+ source concentration on hydrothermally grown ZnO nanorods

We studied the effect of Zn2+ source concentration on the structural and optical properties of hydrothermally grown ZnO nanorods. The nanorods were grown on ZnO/p-Si(111) substrate using by a hydrothermal process in various concentrations of reagent at a low temperature (approximately 95 degrees C) and the structural and optical characteristics of ZnO nanorods were subsequently investigated by X-ray diffraction, field-emission scanning electron microscopy, and room temperature photoluminescence. The results demonstrate that the morphology and crystallinity of ZnO nanorods are influenced by the overall concentration of the precursor. The density and diameter of ZnO nanorods with a hexagonal structure are especially sensitivite to concentration of reactants. Furthermore, the structural transition is shown by increasing concentration. At the lowest concentration of Zn2+, the ZnO nanorods grow as single crystals with a low density and variable orientations. On the contrary, at the highest concentration, the nanorods grow as polycrystas due to the supersaturated Zn2+ source.     

Effects of seed layers on structural, morphological, and optical properties of ZnO nanorods

We studied the effects of seed layers on the structural and optical properties of ZnO nanorods. ZnO and Ag-doped ZnO (ZnO:Ag) seed layers were deposited on glass substrates by magnetron co-sputtering. ZnO nanorods were grown on these seed layers by the chemical bath deposition in an aqueous solution of Zn(NO3)2 and hexamethyltetramine. SEM micrographs clearly reveal that ZnO nanorods were successfully grown on both kinds of seed layers. The XRD patterns indicate that crystallization of ZnO nanorods is along the c-axis. Meanwhile, the packing density and the vertical alignment of the ZnO nanorods on the ZnO seed layer are better than those of the ZnO nanorods on ZnO:Ag. The enhanced growth of nanorods is thought to be due to the fact that the ZnO layer exhibits a higher crystalline quality than the ZnO:Ag layer. According to the low-temperature photoluminescence spectra, the ZnO nanorods on the ZnO seed layer show a narrow strong ultraviolet emission band centered at 369 nm, while those on ZnO:Ag exhibit multiple bands. These results are thought to be related with the crystallinity of ZnO nanorods, the morphologies of ZnO nanorods, and the reflectivities of seed layers. More detailed studies for clarification of the seed layer effect on the growth of ZnO nanorods are desirable.     

Effect of rapid thermal annealing on Zn/ZnO layers

Zn/ZnO layers were deposited on SiO₂/Si substrate by magnetron sputtering at room temperature, and then these layers were annealed at various temperatures from 200 to 400 °C in nitrogen atmosphere for 1 min. The structural and electrical properties of the Zn/ZnO layers before and after annealing are systematically investigated by X-ray diffraction, scanning electron microscopy, current–voltage measurement system, and Auger electron spectroscopy. Current–voltage measurements show that the Zn/ZnO layers exhibit an Ohmic contact behavior. It is shown that, initially, the specific contact resistivity decreases with the increase of the annealing temperature and reaches a minimum value of 9.76 × 10^?5 Ω cm² at an annealing temperature of 300 °C. However, with a further increase of the annealing temperature, the Ohmic contact behavior degrades. This phenomenon can be explained by considering the diffusion of zinc interstitials and oxygen vacancies. It is also shown that Zn-rich ZnO thin films can be obtained by annealing Zn on the surface of ZnO film and that good Ohmic contact between Zn and ZnO layers can be observed when the annealing temperature was 300 °C.     

Uniform ZnO nanorods can be used to improve the response of ZnO gas sensor

Uniform ZnO nanorods were synthesized in high-yield by using metal zinc powder as zinc source via a one-step facile hydrothermal process under mild conditions, in which cetyltrimethylammonium bromide (CTAB) with ordered chain structures acted as the conversion of Zn powder into ZnO nanorods. The characterization results show that the as-synthesized products were structurally uniform and have diameters of 40–80 nm. Gas sensing properties studies show that ZnO nanorods exhibit more excellent response and stability to ethanol than that of ZnO nanoparticles. After working continuously for 50 days, the sensitivity of ZnO nanorods still retained 7.3, whereas, the ZnO nanoparticles showed only 1.0. The facile preparation method and the improved properties derived from typical rods-like nanostructure are significant for the future applications of gas sensing material.     

Effect of phosphorus incorporation on morphology and optical properties of ZnO nanorods

Phosphorus-doped ZnO nanorods have been prepared on Si substrates by thermal evaporation process without any catalyst. X-ray photoelectron spectroscopy and Raman spectra indicate that phosphorus entering into ZnO nanorods mainly occupies Zn site rather than O one. The introduction of phosphorus leads to the morphological changes of nanorods from hexagonal tip to tapered one, which should be attributed to the relaxation of the lattice strain caused by phosphorus occupying Zn site along the radial direction. Transmission electron microscopy shows that phosphorus-doped ZnO nanorods still are single crystal and grow along [0 0 0 1] direction. The effect of phosphorous dopant on optical properties of ZnO nanorods also is studied by the temperature-dependent photoluminescence spectra, which indicates that the strong ultraviolet emission is connected with the phosphorus acceptor-related emissions.     

Growth of aligned ZnO nanorods

Growth of high-density and aligned ZnO nanorods on ZnO film substrate has been demonstrated using vapor-transport of thermally evaporated Zn metal powders followed by condensation. Morphological studies show that the nanorods grow preferentially from a hexagonal ZnO base with a uniform hexagonal structure following three-dimensional island-like growth mechanism. Structural and spectroscopic properties clearly indicate that the nanorods are relatively good and defect-free in quality. These nanorods have potential for technological implications.     

Defect stabilization in ZnO nanorods by Mg2+ doping

Luminescent ZnO and Zn0.95Mg0.05O nanorods with length around 0.5 to 3 microm and diameter 100-150 nm were prepared by a facile solvothermal method. On hydriding at room temperature, a change of morphology from nanorods with aspect ratio 5-10 to particles of sizes 100 nm has been observed in both ZnO and Zn0.95Mg0.05O. While hydrided Zn0.95Mg0.05O showed an enhanced defect related green emission, the same got suppressed in hydrided ZnO. Even though it is observed that zinc vacancies are present in both as prepared ZnO and Zn0.95Mg0.05O, luminescence studies indicate that zinc vacancies get stabilized in Zn0.95Mg0.05O on hydrogenation.     

Investigations on structural, optical and electrical properties of p-type ZnO nanorods using hydrothermal method

Undoped and doped ZnO nanorods were grown from an aqueous solution at low temperature (90 °C) on sapphire (100) substrates coated with ZnO thin film annealed in air at 550 °C for 1 h. X-ray diffraction results show that these nanorods have wurtzite type structure, and they are oriented in the c-axis direction. The optical properties are examined by room temperature micro photoluminescence and Raman scattering analysis which confirm that the nanorods exhibit good optical and electrical properties. A strong enhancement of multiple-phonon Raman scattering process with longitudinal optical phonon overtone up to fifth order was observed. It is found that the thin film coating of ZnO plays an important role in the c-axis oriented growth of undoped and doped ZnO nanorods due to good lattice match between the thin film and nanorods.     

Structural and optical properties of ZnO films grown on the AAO templates

Structural and optical properties of ZnO films grown on Al substrate and anodic alumina oxide (AAO) templates by rf magnetron reactive sputtering deposition were investigated using X-ray diffraction (XRD), atomic-force microscope (AFM) and photoluminescence (PL). We found that ZnO thin films on Al substrate show good C-axis orientation, while the orientation of ZnO film on AAO templates is disordered, this due to the fact that the crystalline of ZnO is greatly influenced by surface morphology of substrates. PL measurements show a blue band in the wavelength range of 400–500 nm caused by the interstitial Zn in the ZnO films. The intensity of emission peak of ZnO films deposited on AAO templates increases compared with that on the Al substrate. Combining electrical resistivity and carrier concentration measurements, we found that that the blue emission intensity is consistent with the concentration for the interstitial zinc in the ZnO films.     

Growth process observation of homoepitaxial ZnO thin films using optical emission spectra during pulsed laser deposition

Homoepitaxial ZnO thin films were prepared on the Zn-polar or O-polar ZnO substrates by pulsed laser deposition method. Optical emission spectroscopy of the plume was carried out to estimate O/Zn flux ratio under the various deposition conditions such as oxygen pressure, laser fluence, and the distance between target and substrate. It is revealed that the O/Zn flux ratio could be controlled by laser fluence, oxygen pressure, and target-substrate distance. Zn-rich O/Zn flux promotes pit formation and O-rich flux yields the three-dimensional growth. The difference of the growth process on Zn-polar or O-polar substrates is also discussed.