A Study on the Influences of Processing Parameters on the Growth of Oxide Nanorod Arrays by Sol Electrophoretic Deposition

Template-based sol electrophoretic deposition has been demonstrated as an attractive method for the synthesis of oxide nanorod arrays, including simple and complex oxides in the forms of amorphous, polycrystalline, and single crystal. This paper systematically studied a number of processing parameters to control nanorod growth by sol electrophoretic deposition. The influences of particle and template zeta potentials, condensation rate, deposition rate (or externally applied electric field), the presence of organic additives, and sol concentration on the growth of nanorod arrays were studied. It was found that higher zeta potential or electric field resulted in higher growth rates but less dense packing. Templates with charge opposite to that of the sol particles prevented formation of dense nanorods, sometimes resulting in nanotubes, depending on the field strength during electrophoresis. In addition, the pH of the sol and chelating additives were also varied and likely affected the deposition process by affecting the condensation reactions.     

一维ZnO纳米棒阵列的水热合成

以锌片为衬底,用硝酸锌和氨水为原材料,在90 ℃时由水热法合成了有序生长的ZnO纳米棒阵列。 纳米棒长度为500～800 nm,直径约为100 nm,SEM图片显示该纳米棒顶部截面是六边形。 XRD谱表明,ZnO纳米棒为六方纤锌矿结构。 考察了制备温度、时间和物料比对合成的材料形貌和结构的影响。     

Cerium-Doped Iron Oxide Nanorod Arrays for Photoelectrochemical Water Splitting

In this work, a simple one-step hydrothermal method was employed to prepare the Ce-doped Fe₂O₃ ordered nanorod arrays (CFT). The Ce doping successfully narrowed the band gap of Fe₂O₃, which improved the visible light absorption performance. In addition, with the help of Ce doping, the recombination of electron/hole pairs was significantly inhibited. The external voltage will make the performance of the Ce-doped sample better. Therefore, the Ce-doped Fe₂O₃ has reached superior photoelectrochemical (PEC) performance with a high photocurrent density of 1.47 mA/cm² at 1.6 V vs. RHE (Reversible Hydrogen Electrode), which is 7.3 times higher than that of pristine Fe₂O₃ nanorod arrays (FT). The Hydrogen (H₂) production from PEC water splitting of Fe₂O₃ was highly improved by Ce doping to achieve an evolution rate of 21 μmol/cm²/h.     

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。     

加氢精制催化剂表面纳米棒束的电子显微镜研究

利用场发射扫描电镜(SEM)、高分辨透射电镜(HRTEM)、X射线能谱仪(EDX)和选区电子衍射(SAED)分析,对实验室硫化态加氢精制催化剂外表面上的纳米棒束的形貌、化学成分、晶体结构进行研究.SEM结果表明,该纳米棒束普遍分布于催化剂外表面并向外生长,纳米棒束形态较为规整,长度为500～1 500 nm,直径为20...     

高度有序氧化钨纳米棒的制备和表征

采用直流磁控溅射法结合阳极氧化法在铝基纳米点阵上制备氧化钨(WO3)纳米棒. 运用原子力学显微镜(AFM), 电子扫描显微镜(SEM), X射线衍射仪(XRD), 电化学工作站(EW)和紫外-可见分光光度计(UV)观察表征了WO3纳米棒的表面形貌、结构、光学性能和电致变色性能. 结果表明: 在溅射过程中, 溅射粒子优先沉积于铝基纳米点阵的凸点上, 然后成核并形成棒状; WO3纳米棒的直径约为200 nm, 与铝基纳米点阵的直径一致, 拥有一定的电致变色性能.     

ZnO纳米棒阵列在TiO2介孔薄膜上的生长及其表征

通过低温水热法成功地将ZnO纳米棒阵列定向生长在了介孔锐钛矿TiO2纳米晶薄膜上,并主要利用X射线衍射、场发射扫描电子显微镜和光致发光光谱等对其进行了表征。所制备的纳米棒具有六边形的端面,纳米棒的尺寸及端面边长分布范围窄,并且沿c轴方向(002)表现出了明显的择优化生长。此外,相比于玻璃基底或TiO2纳米颗粒薄膜,生长在介孔TiO2薄膜上的ZnO纳米棒阵列表现出了较好的取向生长,表明基底的表面结构和组成对ZnO纳米棒阵列的生长有显著的影响。根据基底有序的多孔结构,讨论了纳米棒阵列可能的生长机理。所得到的ZnO纳米棒阵列在室温下分别表现出了以370 nm为中心的强近紫外光和以530 nm为中心的弱绿光两条荧光谱带。     

ZnO/ZnS Heterostructured Nanorod Arrays and Their Efficient Photocatalytic Hydrogen Evolution

Semiconducting heterostructures have been widely applied in photocatalytic hydrogen evolution due to their variable band gaps and high energy conversion efficiency. As typical semiconducting heterostructures, ZnO/ZnS heterostructured nanorod arrays (HNRAs) have been obtained through a simple anion‐exchange process in this work. Structural characterization indicates that the heterostructured nanorods (HNRs) are all composed of hexagonal wurtzite ZnO core and cubic zinc‐blende ZnS shell. As expected, the as‐obtained one‐dimensional heterostructures not only lower the energy barrier but also enhance the separation ability of photogenerated carriers in photocatalytic hydrogen evolution. Through comparisons, it is found that 1D ZnO/ZnS HNRAs exhibit much better performance in photocatalytic hydrogen evolution than 1D ZnO nanorod arrays (NRAs) and 1D ZnS NRAs. The maximum H₂ production is 19.2 mmol h^?1 for 0.05 g catalyst under solar‐simulated light irradiation at 25 °C and the corresponding quantum efficiency is 13.9 %, which goes beyond the economical threshold of photocatalytic hydrogen evolution technology.     

Ti基ZnO纳米棒阵列的制备及其光催化性能研究

采用两电极体系中恒电流电沉积在Ti基底上制得较均一的ZnO纳米棒阵列,利用SEM和XRD观察表征样品,研究Zn(NO₃)₂浓度及电流密度对ZnO纳米棒阵列微观形貌的影响. 以甲基橙为目标降解物,考察该电极光催化性能. 结果表明,Zn(NO₃)₂浓度和电流密度对纳米棒阵列的形貌有显著影响;与ITO玻璃等其他基底相比,在Ti基底上也可沉积较好均一取向的ZnO纳米棒阵列;紫外灯照射下,ZnO/Ti电极对甲基橙（10 mg·L^-1）模拟印染废水降解2.5 h,降解率达到83.3%,光催化活性较佳;无光照时ZnO纳米棒的降解率仅7%.     

Microphase Separation of a Diblock Copolymer Dispersed in Nanorod Arrays Grafted on a Plate: A Monte Carlo Study

The microstructure of a diblock copolymer dispersed in nanorod arrays grafted on a plate are investigated via annealing MC simulation. The confinement in nanorod arrays provides a complex confined space which leads to complicated microphase separation structures. Different morphologies of top and bottom of the film in the nanorod arrays are observed by varying the inducing height of nanorod and its grafting density in the bottom. Due to a short inducing range by the nanorods, the top structures are therefore mainly dominated by the competition between the absolute height of off‐induced layer on the top and the nature of block copolymer itself; while the bottom structures are affected by the symmetry of block copolymer and the gap among rods.

     

Precursor and Solvent Effects in the Nonhydrolytic Synthesis of Complex Oxide Nanoparticles for Bioimaging Applications by the Ether Elimination (Bradley) Reaction

Investigation of the solvent and alkoxide precursor effect on the nonhydrolytic sol–gel synthesis of oxide nanoparticles by means of an ether elimination (Bradley) reaction indicates that the best crystallinity of the resulting oxide particles is achieved on application of aprotic ketone solvents, such as acetophenone, and of smallest possible alkoxide groups. The size of the produced primary particles is always about 5 nm caused by intrinsic mechanisms of their formation. The produced particles, possessing the composition of natural highly insoluble minerals, are biocompatible. Optical characteristics of the perovskite complex oxide nanoparticles can easily be controlled through doping with rare earth cations; for example, by Eu³⁺. They can be targeted through surface modification by anchoring the directing biomolecules through a phosphate or phosphonate moiety. Testing of the distribution of Eu‐doped BaTiO₃ particles, modified with ethylphosphonic acid, demonstrates their facile uptake by the plants with active fluid transport, resulting finally in their enhanced concentration within the cell membranes.     

基于微通道内表面上垂直生长的ZnO纳米棒阵列的微反应器型光催化装置

通过在微通道内表面上制备均匀的ZnO晶种层薄膜,再在晶种膜的基础上制备出了垂直生长的ZnO纳米棒阵列。将长有ZnO纳米棒的微通道用作微反应器,以光催化降解亚甲基蓝(MB)溶液为例考察了流体停留时间和连续重复使用对光催化性能的影响。结果表明,在停留时间为80 s时MB的光降解率为95%,连续重复使用180 h后,MB的降解率仍在80%以上。     

碘氧铋/二氧化钛纳米棒复合材料的制备及其对双酚A的光电化学检测

采用简易的两步水热法在FTO导电玻璃表面合成碘氧铋/二氧化钛纳米棒(BiOI/TiO₂ NRAs)复合材料。通过扫描电子显微镜、X射线单晶衍射仪对该复合材料进行了表征,基于电流-时间法考察了其光电化学行为。 BiOI的负载不仅成功地将TiO₂的光吸收范围拓展到可见光区,同时二者结合形成的p-n异质结构有效地促进光生电子空穴分离,增强了光催化能力。 基于该复合材料对双酚A的光催化氧化作用,建立了一种新型检测双酚A的方法。 结果表明,420 nm可见光激发下,利用电流-时间法,在外加偏压为0.0 V时,光电流密度与双酚A浓度在0.0047~14.7 μmol/L范围内呈线性关系,检测限为0.93 nmol/L(S/N=3)。 该传感器具有高的灵敏度、良好的稳定性及重现性,将其应用于塑料制品和牛奶中的双酚A检测,获得令人满意的结果,回收率为98.0%~107.1%。     

ZnO纳米棒阵列基-芴类共轭聚合物膜的制备及对TNT的检测评价

将共轭芴类荧光聚合物涂覆在纳米Zn O棒阵列上,制成荧光传感膜检测痕量TNT。通过水热法生长的Zn O纳米棒阵列具有较好的取向性,作为衬底可有效增大荧光膜荧光强度,同时,Zn O纳米棒阵列的高比表面积可提高膜对TNT气体的响应效率,使20s内的荧光猝灭率可达72%。     

基底对电沉积制备ZnO纳米棒阵列的影响

采用恒电位电沉积方法, 在未经修饰的ITO导电玻璃基底上通过控制实验条件制备出不同形貌的纳米ZnO结构, 而在经过ZnO纳米粒子膜修饰后的ITO导电玻璃基底上, 制备出透明、高取向、粒径小于30 nm的ZnO纳米棒阵列. 用扫描电子显微镜(SEM)、X射线衍射(XRD)以及透射光谱对制备出的ZnO纳米棒阵列的结构、形貌和透明性进行了表征. 测试结果表明, ZnO纳米棒阵列的平均直径为21 nm, 粒径分布窄, 约18～25 nm, 择优生长取向为[001]方向, 垂直于基底生长. 当入射光波长大于400 nm时, ZnO纳米棒阵列的透光率大于95%.     

Nucleation and Growth Synthesis of Siloxane Gels to Form Functional,Monodisperse, and Acoustically Programmable Particles

Nucleation and growth methods offer scalable means of synthesizing colloidal particles with precisely specified size for applications in chemical research, industry, and medicine. These methods have been used to prepare a class of silicone gel particles that display a range of programmable properties and narrow size distributions. The acoustic contrast factor of these particles in water is estimated and can be tuned such that the particles undergo acoustophoresis to either the pressure nodes or antinodes of acoustic standing waves. These particles can be synthesized to display surface functional groups that can be covalently modified for a range of bioanalytical and acoustophoretic sorting applications.     

Hydrothermal Synthesis of Pencil‐like SAPO‐5 and Observation of Its Reversed Crystal‐Growth Process

SAPO‐5 with a novel hexagonal pencil‐like morphology was hydrothermally synthesized from hydrogels that contain triethylamine and high concentrations of acetic acid at 180 °C for 48 h. The effect of the acetic acid concentration was examined and indicated that usage of a high concentration of acetic acid is crucial to the synthesis of SAPO‐5 with a pencil‐like morphology. The time‐dependent growth process of novel SAPO‐5 was observed by scanning electron microscopy with the aid of acid treatment to remove the amorphous materials for clearer observation. The samples were also characterized by X‐ray diffraction and Fourier‐transform infrared spectroscopy. The results show that the crystal growth at the early stage follows the reversed crystal‐growth route. First, the crystallization occurs on the surface of the aggregated amorphous ellipsoidal particles to form a hexagonal prism crystal shell with the encapsulation of amorphous materials. Then, the amorphous materials wrapped inside start to grow to a hexagonal prism inside the hollow larger hexagonal prism shell. Finally, the interior hexagonal prism continues to grow to the two ends with its length beyond that of the larger one by means of the Ostwald ripening process, thus forming the pencil‐like crystal.     

Generalized Nonaqueous Sol–Gel Synthesis of Different Transition‐Metal Niobate Nanocrystals and Analysis of the Growth Mechanism

A general nonaqueous route for the synthesis of phase‐pure transition‐metal niobate (InNbO₄, MnNb₂O₆, and YNbO₄) nanocrystals was developed based on the one‐pot solvothermal reaction of niobium chloride and the corresponding transition‐metal acetylacetonates in benzyl alcohol at 200 °C. All samples were carefully characterized by XRD, TEM, HRTEM, and energy‐dispersive X‐ray (EDX) analysis. The crystallization mechanism of these niobate nanocrystals points to a two‐step pathway. First, metal hydroxide crystals and amorphous niobium oxide are formed. Second, metal niobate nanocrystals are generated from the intermediates by a dissolution–recrystallization mechanism. The reaction mechanisms, that is, the processes responsible for the oxygen supply for oxide formation, were found to be rather complex and involve niobium‐mediated ether elimination as the main pathway, accompanied by solvolysis of the acetylacetonate ligands and benzylation reactions.     

Structural Features of Phosphate and Sulfate Modified Zirconia Prepared by Sol–Gel Route

This paper describes the effect of sulfate, phosphate and nitrate complexing ligands on the structural features of amorphous xerogels and on the crystallization of metastable zirconia phases during the xerogel-ceramic conversion. Powdered samples were prepared by a sol–gel route using zirconyl chloride precursors chemically modified by complexing ligands. The structural evolution of ZrO₂ phases as function of firing temperature was analyzed by XRPD, EXAFS and ³¹P NMR/MAS. The experimental results show the formation of metastable t-ZrO₂ during the low firing temperature of xerogels modified by sulfate or phosphate groups. The martensitic tetragonal-monoclinic transformation occurs during desorption of sulfate groups. The largest temperature interval of stability of metastable tetragonal zirconia was observed for phosphate-modified xerogels.