ZnO纳米线形态对其光致发光性能的影响

以多孔氧化铝膜为模板,电化学沉积出Zn纳米线,再通过高温氧化得到ZnO纳米线阵列。通过改变制备多孔氧化铝模板的工艺参数来改变模板纳米孔径,进而改变ZnO纳米线的直径,得到不同形态的ZnO纳米线阵列。应用X射线衍射仪、透射电子显微镜测试技术表征了ZnO纳米线的结构与形貌。结果发现,X射线衍射时会出现随ZnO纳米线直径增大衍射峰增多和增强的现象。采用荧光光谱仪测试样品的光致发光性能,通过Gaussian原理对谱峰的拟合分析了ZnO纳米线形态对其光致发光光谱的影响。结果表明,随着纳米线直径从30nm至60nm依次增大,其结晶性和化学计量比逐渐变好。近紫外区和蓝光区的发射峰随着纳米线直径的增大而蓝移,而纳米线直径为60nm的样品则出现随直径增大而红移的现象。结果可见,直径在55~60nm间的某点将是ZnO纳米线的结构和光致发光性能变化的临界点。     

一步湿化学法合成超细金纳米线

以氯金酸(HAuCl₄)为前驱物, 油胺同时作为溶剂、表面稳定剂和还原剂, 通过简单的一步湿化学法合成超细金纳米线. 制备出的超细金纳米线不仅产量高、纯度高, 而且纵横比大, 纳米线平均直径~2 nm, 长度可达数十微米. 如果添加另一种还原剂油酸并调节油胺和油酸的体积比为1:1, 将生成直径为~9 nm的金纳米线. 通过改变反应温度和还原剂用量, 对该种超细金纳米结构的生长机制进行阐述说明: 以油胺为模板, 在油胺和一价金卤化物(AuCl)亲金键合形成的一维聚合链作用下, 被还原的金原子附着在已成核颗粒表面, 一维地生长成超细金纳米线.     

碳辅助CVD制备氧化硅纳米线及其光学性能

利用碳辅助CVD方法, 在1100~1140 ℃、常压、N2/H2气氛下, 以Fe-Al-O复合体系为催化剂, 在石英衬底上制备了大量非晶氧化硅纳米线. 该纳米线直径为20~200 nm, 长数百微米. 利用透射电镜、扫描电镜及电子能谱对氧化硅纳米线的形貌及组分进行了表征与分析; FTIR光谱显示了非晶氧化硅的3个特征峰(482, 806和1095 cm-1)和1132 cm-1无序氧化硅结构的强吸收峰. 氧化硅纳米线的光致发光光谱(PL)表明其具有较强的438 nm荧光峰.     

金、铜金属纳米棒或纳米线的AFM和SERS的研究(英文)

通过电化学氧化法制备具有不同孔径氧化铝模板 ,利用交流电镀的方法在模板中沉积金属 ,再用酸溶解模板可以得到相应尺度的金属纳米线或纳米棒的阵列 .本文利用原子力显微镜和表面增强拉曼技术分别表征了金和铜两种金属纳米线阵列 .研究结果表明 ,作为探针分子的硫氰(SCN )在金属纳米线上的碳氮三键的振动频率随纳米线直径的增大而蓝移 .这一现象可能是因为尺寸效应对纳米线的费米能级造成影响 ,使不同直径的金属纳米线电子结构存在微小的差别 .     

在水热条件下利用微胶束对TiO2纳米线阵列直径的精细调控

通过探讨氧化钛纳米线阵列反应机制,建立了在水热条件下,氧化钛纳米线阵列在亲水掺铟氧化锡表面上由极性/非极性溶剂体系中形成的胶束内反应并生长的模型.并由此利用微胶束的尺寸限制作用,通过温度对微胶束尺寸进行调节,以及Cl^-离子的晶面限制效应,实现了在较大范围内对纳米线直径的调控.另外反应体系中极性与非极性溶液的比例的变化对纳米阵列的直径影响不大,因此可以认为在此反应体系中,氧化钛纳米线的直径主要受到微胶束的限域效应以及Cl^-离子的晶面限制效应影响.此方法可应用于其他相关氧化物纳米材料的尺寸控制合成中.     

金纳米线阵列制备及其光谱特性

利用电化学沉积方法在重离子径迹模板中制备出直径从45 nm到200 nm, 长径比达700的金纳米线阵列, 利用扫描电子显微镜(SEM)和X射线衍射(XRD)对所制备金纳米线的形貌及晶体结构进行分析, 结果表明, 在1.5 V(无参比电极)沉积电压下所制备出的直径为200 nm金纳米线沿[100]晶向具有较好择优取向. 利用紫外-可见光谱(UV-Vis)对镶嵌在透明模板中平行排列的金纳米线阵列光学特性进行研究, 发现金纳米线直径为45 nm时, 其紫外可见光谱在539 nm处有强烈吸收峰, 随着金纳米线直径增加, 吸收峰红移, 当金纳米线直径达到200 nm时, 其吸收峰峰位移至700 nm. 结合金纳米颗粒相关表面等离子体共振吸收效应对实验结果进行了讨论.     

电化学沉积金纳米线结构及其电学特性

用电化学沉积方法,在有机介孔模板上制备出直径为90nm的金纳米线.透射电子显微镜(TEM)分析结果表明,纳米线表面光滑并呈单晶结构.去除有机模板的金纳米线阵列用扫描电子显微镜(SEM)测试,纳米线顶端呈平台状,直径分布均一.我们利用原子力显微镜(AFM)测量了金纳米线阵列的微观结构,得到与SEM相一致的结果.在大气和室温条件下,用导电AFM针尖在接触模式下测量了单根纳米线的轴向I-V特性曲线,其结果为金属性.     

银纳米线的TEM表征

通过交流电沉积的方法,以多孔铝阳极氧化膜（Al2O3/Al）为模板,制备金属银纳米线.透射电子显微镜（TEM）分析表明, 银纳米线长度平均约为5 μm, 直径25 nm；银纳米线在多孔Al2O3/Al孔内互相平行,显示凸凹相间的条纹结构.选区电子衍射（SAED）证实,银纳米线具有面心立方（FCC）的多晶结构,探讨了银纳米线凸凹相间条纹结构的形成机理.     

用离子吸附法制备银/聚吡咯同轴纳米电缆

以多元醇还原反应法制备出直径为40~50 nm的纳米银线, 采用醋酸铜水溶液对银纳米线表面进行处理, 通过离子吸附在纳米银线表面吸附铜离子. 以吸附在银纳米线表面上的铜离子作为活性单元, 氧化吡咯单体聚合, 制得Ag/PPy同轴纳米电缆. 采用TEM, FTIR和XPS等表征手段对产物进行表征和检测, 并通过表面增强拉曼光谱进一步证实产物中聚吡咯层紧密地吸附在银线表面. 结果表明, 利用醋酸铜作为氧化剂, 通过离子吸附法制备的Ag/PPy同轴纳米电缆, 可以在较大范围内有效地控制聚吡咯层厚度, 避免银纳米线被刻蚀.     

电化学沉积金纳米线结构及其电学特性

用电化学沉积方法，在有机介孔模板上制备出直径为90 nm的金纳米线.透射电子显微镜（TEM）分析结果表明，纳米线表面光滑并呈单晶结构.去除有机模板的金纳米线阵列用扫描电子显微镜（SEM）测试，纳米线顶端呈平台状，直径分布均一.我们利用原子力显微镜（AFM）测量了金纳米线阵列的微观结构，得到与SEM相一致的结果.在大气和室温条件下，用导电AFM针尖在接触模式下测量了单根纳米线的轴向I－V特性曲线，其结果为金属性.     

Ultralong cadmium hydroxide nanowires: synthesis, characterization, and transformation into CdO nanostrands

Ultralong Cd(OH)2 nanowires were fabricated by a hydrothermal method from Cd(CH3COO)2 x H2O (0.01 mol/L) and C6H12N4 (0.015 mol/L) aqueous solution at 95 degrees C for 16 h without using any templates and were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). The length of the nanowires reached several micrometers, giving an aspect ratio of a few thousands. The formation mechanism of the nanowires is attributed to the oriented attachment of small particles. The growth method for the 1D nanostructure presented here offers an excellent tool for the design of other advanced materials with anisotropic properties. The Cd(OH)2 nanowires efficiently captured negatively charged dye, and the adsorbed dye molecules can be released after the addition of EDTA. The Cd(OH)2 nanowires as template compounds were further transformed into CdO semiconductor nanomaterials with similar morphology by calcination under 350 degrees C in air for 3 h.     

Hydrothermal synthesis of ultralong and single-crystalline Cd(OH)2 nanowires using alkali salts as mineralizers

Ultralong and single-crystalline Cd(OH)(2) nanowires were fabricated by a hydrothermal method using alkali salts as mineralizers. The morphology and size of the final products strongly depend on the effects of the alkali salts (e.g., KCl, KNO(3), and K(2)SO(4) or NaCl, NaNO(3), and Na(2)SO(4)). When the salt is absent, only nanoparticles are observed in TEM images of the products. The 1D nanostructure growth method presented herein offers an excellent tool for the design of other advanced materials with anisotropic properties. In addition, the Cd(OH)(2) nanowires might act as a template or precursor that is potentially converted into 1D cadmium oxide through dehydration or into 1D nanostructures of other functional materials (e.g., CdS, CdSe).     

Fabrication of Cu(OH)_2 Nanowires Blended Poly(vinylidene fluoride) Ultrafiltration Membranes for Oil-Water Separation

Cu(OH)_2 nanowires were prepared and incorporated into poly(vinylidene fluoride)(PVDF) to fabricate Cu(OH)_2-PVDF ultrafiltration(UF) membrane via immersion precipitation phase inversion process. The effect of Cu(OH)_2 nanowires on the morphology of membranes was investigated by X-ray photoelectron spectroscopy(XPS), Fourier transform infrared(FTIR) spectroscopy, atomic force microscopy(AFM), scanning electron microscopy(SEM) and X-ray diffraction(XRD) measurements. The results showed that all the Cu(OH)_2-PVDF membranes had wider fingerlike pore structure and better hydrophilicity, smoother surface than pristine PVDF membrane due to the incorporation of Cu(OH)_2 nanowires. In addition, water flux and bovine serum albumin(BSA) rejection were also measured to investigate the filtration performance of membranes. The results indicated that all the Cu(OH)_2-PVDF membranes had high water flux, outstanding BSA rejection and excellent antifouling properties. It is worth mentioning that the optimized performance could be obtained when the Cu(OH)_2 nanowires content reached 1.2 wt%. Furthermore, the membrane with 1.2 wt% Cu(OH)_2 nanowires showed outstanding oil-water emulsion separation capability.     

Controllabe growth of cadmium hydroxide nanostructures by hydrothermal method

We proposed a general hydrothermal strategy for the fabrication of one-dimensional cadmium hydroxide nanostructures.Through controlled experimental conditions, such as solvent properties, salt concentration and alkaline concentration, the different morphologies and dimensions of the final products have been controlled. With this method, Cd(OH)₂ nanowires were prepared readily. XRD, TEM, FESEM and UV-vis absorption spectroscopy were used to characterize the nanowires product, which revealed that the Cd(OH)₂ nanowires consisted of about 30 nm in diameter and length up to several hundreds of nanometers. The optical absorption spectrum indicates that the Cd(OH)₂ nanowires have a indirect band gap of ～2.56 eV. In addition, the as-prepared Cd(OH)₂ nanowires acting as a precursor was converted into porous cadmium oxide through dehydration.     

Photoluminescence and Raman scattering from catalytically grown Zn(x)Cd(1-x)Se alloy nanowires

Zn(x)Cd(1-x)Se alloy nanowires, with composition x = 0, 0.2, 0.5, 0.7, and 1, have been successfully synthesized by a chemical vapor deposition (CVD) method assisted with laser ablation. The as-synthesized alloy nanowires, 60-150 nm in diameter and several tens of micrometers in length, complied with a typical vapor-liquid-solid (VLS) growth mechanism. The Zn(x)Cd(1-x)Se nanowires are single crystalline revealed from high-resolution transmission electron microscopic (HRTEM) images, selected area electron diffraction (SAED) patterns, and X-ray diffraction (XRD) measurement. Compositions of the alloy nanowires can be adjusted by varying the precursor ratios of the laser ablated target and the CVD deposition temperature. Crystalline structures of the Zn(x)Cd(1-x)Se nanowires are hexagonal wurtzite at x = 0, 0.2, and 0.5 with the [0 1 -1 0] growth direction and zinc blende at x = 0.7 and 1 with the [1 -1 1] growth direction. Energy gaps of the Zn(x)Cd(1-x)Se nanowires, determined from micro-photoluminescence (PL) measurements, change nonlinearly as a quadratic function of x with a bowing parameter of approximately 0.45 eV. Strong PL from the Zn(x)Cd(1-x)Se nanowires can be tuned from red (712 nm) to blue (463 nm) with x varying from 0 to 1 and has demonstrated that the alloy nanowires have potential applications in optical and sensory nanotechnology. Micro-Raman shifts of the longitudinal optical (LO) phonon mode observed in the Zn(x)Cd(1-x)Se nanowires show a one-mode behavior pattern following the prediction of a modified random element isodisplacement (MREI) model.     

Hydrolysis constants and ion-interaction parameters for Cd(II) in zero to high concentrations of NaOH−KOH,and the solubility product of crystalline Cd(OH)2

The solubility of Cd(OH)₂(c) was studied in 0.01M NaClO₄ solutions, from both the over- and the undersaturation directions, with OH^– ion concentration ranging from 10^–6 to 1.0 mol-L^–1, and the equilibration period ranging from 2 to 28 days. Equilibrium Cd concentrations were reached in less than 2 days. The Cd(OH)₂(c) solubility showed an amphoteric behavior. In the entire range of OH^–/H⁺ investigated, the only dominant aqueous Cd(II) species required to explain the solubility of Cd(OH)₂(c) are Cd²⁺, Cd(OH) ₂ ⁰ , and Cd(OH) ₄ ^2– . The logarithms of the thermodynamic equilibrium constants of the Cd(OH)₂(c) solubility reactions involving these species, that is, the reactions

Room temperature electrodeposition of photoactive Cd(OH)2 nanowires

Cd(OH)₂ nanowires (NWs) were successfully prepared by room temperature electrogeneration of base using Cd(NO₃)₂ aqueous electrolyte and Anodic Alumina Membrane (AAM) as template. Cd(OH)₂ films have been also deposited on tin-doped indium oxide (ITO) for comparison. SEM analysis shows high quality deposits made of closely packed nanowires (NWs) into AAM and uniform flake-like surface on ITO. XRD analysis reveals that Cd(OH)₂ films on ITO are polycrystalline, while the nanowires grow along the preferential directions [1 0 0] and [1 1 0]. Photoelectrochemical measurements show that Cd(OH)₂ NWs are photoactive materials with indirect and direct band gap of 2.15 and 2.75 eV, respectively.     

氢氧化镍纳米线/三维石墨烯复合材料的制备及其电化学性能

采用水热法制备了氢氧化镍纳米线/三维石墨烯复合材料及作为比较的三维石墨烯、氢氧化镍纳米线、还原氧化石墨烯和氢氧化镍纳米线/还原氧化石墨烯, 通过X射线衍射、扫描电镜、热失重分析和氮气吸脱附表征了材料的形貌、结构和组成, 并采用循环伏安法和恒电流充放电测试了复合材料的电化学性能. 结果表明: 氢氧化镍纳米线/三维石墨烯复合材料中直径为20-30 nm的氢氧化镍纳米线和三维结构的石墨烯紧密结合, 相互交联形成网状结构, 其比表面积达到136 m²·g^-1, 孔径分布20-50 nm, 氢氧化镍纳米线的含量达到88% (w,质量分数). 在6 mol·L^-1的KOH电解液中, 复合材料的比电容在1 A·g^-1电流密度下达到1664 F·g^-1, 在1 A·g^-1电流密度下循环3000 次后的比电容保持率为93%. 将复合材料的比电容和循环性能与氢氧化镍纳米线、氢氧化镍纳米线/还原氧化石墨烯、三维石墨烯和还原氧化石墨烯的性能进行比较, 发现三维石墨烯较还原氧化石墨烯具有更高的比表面积和三维多孔结构, 可以更大地提高活性物质的利用率, 进而提高复合材料的比电容和稳定性.     

CdSe纳米线阵列的制备及其表征(英)

通过在含有SeSO₃^2-和Cd²⁺的室温水溶液中，用模板-电沉积法在纳米孔阵列阳极氧化铝膜(AAM)模板中制备了高有序性的CdSe纳米线阵列，并对其形貌、结构和组分进行了表征。扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果表明，纳米线阵列中的CdSe纳米线具有相同的长度和直径，分别对应于使用的AAM模板的厚度和孔径；X-射线衍射(XRD)和X-射线能谱(EDAX)结果表明，CdSe纳米线中Cd和Se的化学组成非常接近于1∶1，其结构为立方CdSe。另外，对模板-电沉积法制备CdSe纳米线的机理进行了讨论。     

Solution synthesis of germanium nanowires using a Ge2+ alkoxide precursor

A simple solution synthesis of germanium (Ge0) nanowires under mild conditions (<400 degrees C and 1 atm) was demonstrated using germanium 2,6-dibutylphenoxide, Ge(DBP)2 (1), as the precursor where DBP = 2,6-OC6H3(C(CH3)3)2. Compound 1, synthesized from Ge(NR2)2 where R = SiMe3 and 2 equiv of DBP-H, was characterized as a mononuclear species by single-crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 degrees C under an atmosphere of Ar, led to the formation of Ge0 nanowires. The Ge0 nanowires were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1-10 microm) increases with increasing temperature (285-315 degrees C) and time (5-60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire; and (2) self-assembly mechanism where an aggregate of small rods (<50 nm in diameter) recrystallizes on the tip of a longer wire, extending its length.