ZnO纳米棒的制备及其光催化活性研究

以Zn(Ac)2·2H2O、NaI和N2H4·H2O为原料,在未使用任何表面活性剂的简单水热反应体系中制得了ZnO纳米棒.采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物的晶体结构、形貌进行了表征分析,并对其光催化活性进行了探讨,以ZnO纳米棒为光催化剂对有机染料污染物甲基橙进行了光催化降解实验.实验结果表明,氧化锌纳米棒对甲基橙的光催化降解具有很好的催化作用,在紫外光照射120min后,对甲基橙的降解率接近完全.     

纳米ZnO的形貌对光催化降解焦炭废水效果的研究

制备了片状多孔、花状、球状、棒状和菱形的纳米ZnO粒子,采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)进行表征,并研究了片状多孔、花状、球状、棒状和菱形的纳米ZnO颗粒对焦炭废水的降解以及其不同形貌对光催化处理焦炭废水效果的影响。结果表明,不同形貌纳米ZnO的光催化降解焦炭废水能力大小顺序为:片状多孔>花状>球状>棒状>菱形,当片状多孔纳米ZnO的加入量为焦炭废水质量的2%,降解时间为0.5 h,其吸附性能与催化效果达到最佳。     

纳米ZnO的形貌对光催化降解焦炭废水效果的研究

制备了片状多孔、花状、球状、棒状和菱形的纳米ZnO粒子,采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)进行表征,并研究了片状多孔、花状、球状、棒状和菱形的纳米ZnO颗粒对焦炭废水的降解以及其不同形貌对光催化处理焦炭废水效果的影响。结果表明,不同形貌纳米ZnO的光催化降解焦炭废水能力大小顺序为:片状多孔>花状>球状>棒状>菱形,当片状多孔纳米ZnO的加入量为焦炭废水质量的2%,降解时间为0.5 h,其吸附性能与催化效果达到最佳。     

氧化锌纳米晶的制备及光催化性能研究

采用沉淀-热分解方法制备纳米ZnO,并用场发射扫描电子显微镜和X-射线衍射仪分析所制备的ZnO粉体的晶粒大小和物相,同时研究了在不同煅烧温度下制备的纳米ZnO对次甲基蓝的光催化降解效率.实验结果表明:在450 ℃下煅烧2 h制备的ZnO粉体的粒径基本分布在20～40 nm的范围内,且具有(假)六方结构.将在400 ℃和500 ℃下合成的ZnO纳米晶相比,在450 ℃下合成的样品对次甲基蓝的光催化降解效率较高;此外,外加适量的30%H2O2(质量含量,下同)溶液能显著提高纳米ZnO对次甲基蓝的光催化降解效率.     

MoS2/ZnO纳米复合材料的光学和光催化性能

在溶剂热法制备ZnO纳米粒子的基础上,利用物理剥离和纳米粒子互剪切作用成功制备了MoS₂/ZnO异质结构纳米复合物。以扫描电子显微镜、透射电子显微镜、X射线能量色散光谱、粉末X射线衍射、拉曼光谱仪、紫外-可见漫反射光谱、光致发光谱等对样品进行了结构形貌和性能表征。结果表明,利用物理剥离和互剪切作用能有效地获得MoS₂/ZnO复合物,复合作用使得MoS₂位于378cm^-1(E¹_2g)和400cm^-1(A_1g)处的两个特征拉曼峰显著增强。复合物中MoS₂含量越少,两个特征拉曼峰强度反而越高,且两峰波数间隔相应减小。可归因于MoS₂含量较低时,ZnO纳米粒子对MoS₂的物理剥离效果越显著,同时,MoS₂体现出良好的分散性和较小的厚度。MoS₂含量对MoS₂/ZnO的发光具有明显的调制作用,显著增强了复合物在可见光区域的吸收。随着MoS₂含量增加,其可见光发光强度迅速减小,紫外峰出现明显的蓝移。纯ZnO对苯酚的降解率最高达90%,而MoS₂/ZnO复合物对苯酚的降解率达100%,复合物对苯酚的最终降解率明显高于纯氧化锌。     

木质素碳/氧化锌复合材料的制备及其光催化性能

以来源于造纸黑液的碱木质素和草酸锌为前驱体采用原位碳化法制备了不同碳含量的木质素碳/氧化锌(LC/ZnO)纳米复合材料。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外分光光度计(UV-Vis)、荧光光谱仪(PL)等对所制备的LC/ZnO的微观结构和光学性质进行了表征。结果表明所制备的LC/ZnO复合材料是由高度分散的ZnO纳米颗粒和木质素碳纳米片构成,表现出优异的紫外和可见光吸收性能。以常见的有机污染物罗丹明B为降解对象,在模拟太阳光的照射下对所制备的LC/ZnO复合材料的光催化性能进行了研究。结果表明,LC/ZnO复合材料的光催化性能明显优于纯的ZnO纳米颗粒和氧化石墨烯/ZnO复合材料,且在550℃炭化温度下所制备的LC/ZnO-550复合材料具有最佳的光催化性能。     

ZnO纳米棒阵列的改进水热方法制备、银修饰及光催化活性研究

ZnO纳米棒阵列是近来研究较多的光催化剂,通过银等贵金属修饰可提高光催化活性。以硝酸锌和六亚甲基四胺为前驱物,通过优化水热合成参数（包括种子层和水热生长液浓度等）以及光化学还原沉积银制备高活性ZnO纳米棒阵列。利用扫描电子显微镜、X射线粉末衍射以及紫外-可见漫反射光谱对样品进行表征。结果表明,种子层和水热反应液浓度均对ZnO纳米棒阵列的活性产生影响。银修饰后,光吸收增强,吸收带边从紫外光区拓展到可见光区。光催化降解甲基橙溶液结果表明,银修饰的ZnO纳米棒阵列较纯ZnO纳米棒阵列降解甲基橙的活性提高30%。     

ZnO/C-dots/Ag复合材料的制备及其增强光催化降解抗生素性能

通过溶剂热法制备了ZnO纳米棒,进一步在ZnO纳米棒表面沉积碳点(C-dots)和Ag,成功制备了C-dots和Ag共修饰的ZnO纳米复合光催化剂(ZnO/C-dots/Ag)。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积(BET)和紫外可见(UV-Vis)分光光谱等分析对系列样品进行了物理表征。结果表明,C-dots的引入可以有效加速Ag在ZnO表面的沉积。在白光下降解抗生素(诺氟沙星)的结果表明,ZnO/C-dots/Ag复合材料的光催化性能相比于纯的ZnO、ZnO/C-dots和ZnO/Ag材料得到了明显的提升,并且光催化性能稳定。表明C-dots和Ag在ZnO光催化降解抗生素过程中起到了协同作用,C-dots起到实现光生电子快速转移的作用,配合Ag的等离子体共振效应共同加速了ZnO的光催化降解过程。     

掺N纳米ZnO的制备及光催化活性

采用溶胶-凝胶法合成纳米ZnO,用碳酸铵溶液浸渍的方法对其进行N掺杂。利用X射线衍射仪,透射电子显微镜,X射线能谱仪,Fourier红外光谱仪,X射线光电子能谱仪,紫外-可见光谱仪对产物结构进行了表征,通过可见光催化降解甲基橙对N-ZnO的光催化活性进行了考察。结果表明:合成的ZnO颗粒大小在20～30 nm,N的掺杂没有改变ZnO的晶型,N在ZnO晶格中形成N—Zn—O键;N掺杂拓宽了ZnO的可见光吸收范围。N-ZnO作为光催化剂在可见光作用下能有效降解甲基橙,表现出较高的可见光催化活性。当(NH4)2CO3和ZnO的摩尔比为0.20时,N-ZnO的光催化性能最好。     

稀土掺杂ZnO光催化降解偏二甲肼废水研究

利用水热法制备稀土掺杂ZnO/La3+、ZnO/Ce3+、ZnO/Y3+纳米颗粒,用于光催化降解偏二甲肼废水。结果表明,掺杂ZnO颗粒大小均匀,直径在100～200 nm,纯度高。2 h后,对30 mg/L偏二甲肼废水的最大降解率分别为80.4%,82.3%,67.8%,降解率较纳米复合ZnO平均提高80%以上。     

表面活性剂对氧化锌纳米棒形貌的影响与机理

分别以PEG400和PVA124为表面活性剂辅助水热法合成了氧化锌(ZnO)纳米棒.X射线衍射分析显示:产物为结晶良好的六角结构ZnO晶体,PEG400为表面活性剂制得的ZnO比PVA124为表面活性剂时的结晶性好.用透射电镜和选区电子衍射研究了不同表面活性剂对ZnO纳米棒形貌和结晶性的影响,解释了PEG400和PVA124对ZnO形貌影响的机理,并对ZnO的生长机制进行了初步探讨.     

Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

ABSTRACT: One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods.     

溶剂热法合成氧化锌纳米棒

采用PEG辅助溶剂热合成了ZnO纳米棒,通过SEM、EDS和XRD等手段对产物进行了表征。结果显示,合成的ZnO纳米棒直径在20 nm左右,长大约150,且长度和直径分布均匀。研究了PEG的添加量对形成ZnO纳米棒的影响,并且探讨了PEG促进纳米棒生长的机理。     

Improved photocatalytic performance of Gd and Nd co-doped ZnO nanorods for the degradation of methylene blue

This paper reports the synthesis of pure ZnO, Gd and Nd co-doped ZnO nanorods based nanocomposites via simple hydrothermal method. Subsequently, the prepared photocatalysts were characterized using XRD, SEM/EDX, TEM, UV–visible and PL spectroscopy. The XRD results demonstrate that Gd and Nd ions were incorporated into ZnO lattice in the synthesized ZnO based nanocomposites and showed hexagonal wurtzite structure. The SEM and TEM results show that nanorods having nanoscale diameter and length were successfully synthesized by hydrothermal method. The UV–visible spectroscopy verified that the band gap of ZnO was reduced due to incorporation of Gd and Nd into ZnO photocatalyst. Similarly, Gd and Nd incorporation into ZnO was found effective to reduce the recombination of electrons and holes as confirmed by PL spectroscopy. Moreover, the prepared nanocomposites with various atomic ratios (0.5–2%) were tested for photocatalytic degradation of methylene blue (MB), under visible light irradiation. The highly efficient and optimized 1.5% Nd/ZnO nanocomposite demonstrated enhanced photocatalytic performance for the degradation of methylene blue compared to pure ZnO and other nanocomposites. Furthermore, the recycling results show that the 1.5% Nd/ZnO nanocomposites displayed good stability and long-term durability. These finding suggest that the ZnO based nanocomposite could be efficiently used in various energy and environmental applications.     

Microcontact Printing of Organic Self-Assembled Monolayers for Patterned Growth of Well-Aligned ZnO Nanorod Arrays and their Field-Emission Properties

This paper describes a simple method for preparing well-aligned ZnO nanorod arrays in a more tunable fashion, which enables the synthesis of nanorods directly in various patterns and the easy control of the array density. This method is based on a combination of the microcontact printing process for patterning and a solution approach for depositing ZnO nanorods. The growth behavior between the contact and noncontact areas is investigated. Different formation mechanisms are proposed, and it is found that the key difference between nanorod and microrod forms was the ZnO seed layer and the van der Waals force at specific conditions. The role of self-assembled monolayers of octadecyl-trichloro-silane in the reaction solution is also discussed. Wettability of the surfaces is assessed by measuring the water contact angle, and the results show significant variation with surface morphology, from 17.6° to 123.6°. The lowest turn-on applied field strength is 4.65 V/μm at the current density of 10 μA/cm², which is achieved by the lowest array density of nanorods. The field-emission characteristics of the nanorods are found to be highly reproducible. The results could be valuable for the application of field-emission-based devices using ZnO nanorod arrays as cathode materials.     

Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires

Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In₂O₃ structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO.     

Selective patterning of ZnO nanorods on silicon substrates using nanoimprint lithography

In this research, nanoimprint lithography (NIL) was used for patterning crystalline zinc oxide (ZnO) nanorods on the silicon substrate. To fabricate nano-patterned ZnO nanorods, patterning of an n-octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on SiO₂ substrate was prepared by the polymer mask using NI. The ZnO seed layer was selectively coated only on the hydrophilic SiO₂ surface, not on the hydrophobic OTS SAMs surface. The substrate patterned with the ZnO seed layer was treated with the oxygen plasma to oxidize the silicon surface. It was found that the nucleation and initial growth of the crystalline ZnO were proceeded only on the ZnO seed layer, not on the silicon oxide surface. ZnO photoluminescence spectra showed that ZnO nanorods grown from the seed layer treated with plasma showed lower intensity than those untreated with plasma at 378 nm, but higher intensity at 605 nm. It is indicated that the seed layer treated with plasma produced ZnO nanorods that had a more oxygen vacancy than those grown from seed layer untreated with plasma. Since the oxygen vacancies on ZnO nanorods serve as strong binding sites for absorption of various organic and inorganic molecules. Consequently, a nano-patterning of the crystalline ZnO nanorods grown from the seed layer treated with plasma may give the versatile applications for the electronics devices.     

ZnO纳米棒水热法生长与表征

采用两步法在FTO导电玻璃衬底上制备ZnO纳米棒,首先利用浸渍-提拉法在FTO导电玻璃衬底上制备ZnO晶种层,然后把有ZnO晶种层的FTO衬底放入盛有生长溶液的反应釜中利用水热法制备ZnO纳米棒.研究了生长溶液的浓度、生长温度和生长时间对所制备的对ZnO纳米棒阵列的微结构和光致发光性能的影响,利用X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光谱(PL)研究了ZnO样品的结构、形貌和光学性质.实验结果表明:所制备的ZnO纳米棒呈现六方纤锌矿结构,沿(002)晶面择优取向生长,纳米棒的平均直径约为100 nm,长度约为2.5 μm.所制备的ZnO纳米棒在390 nm附近具有很强的紫外发光峰和在550 nm附近有较弱的宽绿光发光峰.     

Nanoseed-assisted rapid formation of ultrathin ZnO nanorods for efficient room temperature NO2 detection

The influence of ZnO nanoseeds on the formation of ZnO nanorods from ε-Zn(OH)₂ in NaOH solution at 80 °C was investigated, using ZnO nanoparticles with a diameter of 4–10 nm as the seeds. The experimental results indicated that the presence of ZnO nanoseeds promoted the rapid heterogeneous formation of ultrathin ZnO nanorods. Compared with the ZnO submicron rods with a diameter of 0.5–1.0 µm, the ultrathin ZnO nanorods with a diameter of 10–15 nm were found to be more sensitive for detecting NO₂ at room temperature owing to their higher variation of channel conduction to the diameter.     

Morphological exploration of chemical vapor–deposited P-doped ZnO nanorods for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is beneficial and has received attractive attention due to a greater potential to generate hydrogen and oxygen from water by using plentiful solar light to solve the problem of energy crisis. Various active semiconductor materials are used in PEC water splitting applications. Nevertheless, in past decades, most of the researchers suggested that titanium oxide (TiO₂) is the best photoanode for this type of applications. Now, Zinc oxide (ZnO) is considered a perfect substitution to TiO₂ due to its comparable energy band structure and superior photogenerated electron transfer rate. In this study, bare and phosphorous-doped ZnO nanorods were successfully developed on fluorine-doped tin oxide-coated glass (FTO) substrate by chemical vapor deposition. X-ray diffraction (XRD) pattern authenticated hexagonal structure formation with strong diffraction peak of (101), which showed that ZnO nanorods were perfectly developed along c axis. The optical and morphological properties were analyzed by UV–Vis and scanning electron microscopy images. The energy-dispersive X-ray spectra demonstrated that doping agent phosphorous was present in ZnO nanorods. The PEC properties of the developed ZnO nanorods were further investigated and obtained results suggested that a small amount of phosphorous-doped ZnO nanorods enhances their PEC performance.