Nanotube Arrays in Porous Anodic Alumina Membranes

This review summarizes the various techniques developed for fabricating nanotube arrays in porous anodic alumina membranes （AAMs）. After a brief introduction to the fabrication process of AAMs, taking carbons, metals, semiconductors, organics, biomoleculars, and heterojunctions as typical examples, attention will be focused on the recently established methods to fabricate nanotubes in AAM, including electrochemical deposition, surface sol-gel, modified chemical vapor deposition, atomic layer deposition, and layer-by-layer growth. Every method is demonstrated by one or two reported results. Finally, this review is concluded with some perspectives on the research directions and focuses on the AAM-based nanotubes fields.

Size-Tunable Porous Anodic Alumina Nano-Structure for Biosensing

A porous anodic alumina (PAA) film has been investigated to realise highly-ordered nano-porous structures. A two-step anodization process is used to anodize aluminium into size-controllable aluminium oxide. In this paper, we investigate how anodization parameters affect nano-porous structures, such as voltage and time of pretreatment, anodization voltage and time, pore widening time. The results showed pretreatment is important to obtain a smooth surface for anodizing. The pore size is controllable between 30 and 80 nm, with a linear fit curve. The interpore size is constant at around 95 nm, and the pore densities are between 1010 and 1011 cm–2. The formation of straight vertical walls is crucial if the PAA film is to be subsequently used as the template for the growth of metal nanowire arrays.

Synthesis of Biomimetic Superhydrophobic Surface through Electrochemical Deposition on Porous Alumina

The superhydrophobicity of plant leaves is a benefit of the hierarchical structures of their surfaces. These structures have been imitated in the creation of synthetic surfaces. In this paper, a novel process for fabrication of biomimetic hierarchical structures by electrochemical deposition of a metal on porous alumina is described. An aluminum specimen was anodically oxidized to obtain a porous alumina template, which was used as an electrode to fabricate a surface with micro structures through electrochemical deposition of a metal such as nickel and copper after the enlargement of pores. Astonishingly, a hier- archical structure with nanometer pillars and micrometer clusters was synthesized in the pores of the template. The nanometer pillars were determined by the nanometer pores. The lbrmation of micrometer clusters was related to the thin walls of the pores and the crystallization of the metal on a flat surface. From the as-prepared biomimetic surfaces, lotus-leaf-like superhydrophobic surfaces with nickel and copper deposition were achieved.

Preparation of Porous Alumina Film on Aluminum Substrate by Anodization in Oxalic Acid

Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.

Frequency Shifts of Luminescence for ZnO Nanoparticles in Porous Alumina Template

ZnO nanoparticles in porous anodized alumina were fabricated by sol-gel method. The PL spectra of pure ZnO nanoparticles, porous alumina template and the ZnO/PAA composite system were investigated after annealed at different temperatures. The annealing of ZnO/PAA composite system displays very complicated behavior, where changing of luminescence intensity and a "red shift" of emission frequency were observed at less or higher than 500 ℃ of the annealing temperature, respectively. To explain the phenomenon, it is considered that the emission origin of the green luminescence of ZnO nanoparticles came from OZn. It is suggested that the ZnO/PAA composite system should be annealed at the temperature above 500 ℃ in order to get intense luminescence of ZnO nanoparticle.

A novel approach to large-scale formation of through-hole porous anodic aluminum template

A novel anodic oxidization equipment was designed to fabricate a large number of porous anodic alumina （PAA） templates in one time. This approach improved the efficiency of the preparation of the PAA templates remarkably in a normal lab and is expected to be used for the large-scale production in the future.

Electrochemical Self-Assembly of Nanoporous Alumina Templates Title

Porous alumina was fabricated electrochemically through anodic oxidation of aluminum by means of such a self-organized method. Anodic aluminium oxide (AAO) template with nanopores was grown by two-steps anodization processes from a high purity aluminium foil. The anodization process was carried out in a phosphoric acid electrolyte at ambient temperature with a different duration of anodization. The analysis observation by Atomic Force Microscopy (AFM) showed that nanopore size increased with anodization time. The nanopore sizes of porous alumina were (16.04, 26.19 and 37.39 nm) for (1, 2 and 3 hour) respectively.

从壁垒型氧化膜生长过程研究PAA的生长机制

为研究PAA的生长机理,设计了铝在3种电解液中的阳极氧化,通过SEM和阳极氧化曲线详细分析了规则圆柱形孔道和表面不规则孔洞产生的原因。电解液中阴离子使氧化膜变成了壁垒层和污染层两层。雪崩电子电流导致了在壁垒层/污染层界面上O2的析出。PAA中圆柱形孔道的形成是氧气析出的结果,传统的"酸性场致溶解"只在表面形成不规则的孔洞。当电解液中磷酸含量减少后,氧气析出持续的时间降低,O2析出停止后,多孔孔道被新生成的氧化铝封堵,最后PAA膜转变成BAA膜。

CaO-SiO_2/PAA复合膜的制备及其体外生物活性

以四水合硝酸钙为钙源、正硅酸乙酯为硅源(按CaO/SiO2摩尔比1∶1),采用溶胶-凝胶法制备出CaO-SiO2生物玻璃溶胶.采用压力诱导的方法将CaO-SiO2溶胶注入多孔阳极氧化铝(PAA)的纳米孔道中,经550℃热处理,得到CaO-SiO2/PAA复合膜.所得样品在模拟体液(SBF)中分别浸泡1和7d,观察其表面诱导形成类骨磷灰石的能力.通过扫描电镜(SEM)、X射线能谱仪(EDS)、傅里叶变换红外衍射仪(FTIR)对浸泡前后样品的微观形貌和成分进行表征.试验结果表明:钙硅基生物活性材料能够装载在PAA的纳米孔道中,并且装载有钙硅基材料的PAA在SBF中浸泡后能诱导类骨磷灰石的生成.

POROUS MEMBRANE TEMPLATED SYNTHESIS OF POLYMER PILLARED LAYER

The anodic porous alumina membranes with a definite pore diameter and aspect ratio were used as templates tosynthesize polymer pillared layer structures. The pillared polymer was produced in the template membrane pores, and thelayer on the template surfaces. Rigid cured epoxy resin, polystyrene and soft hydrogel were chosen to confirm themethodology. The pillars were in the form of either tubes or fibers, which were controlled by the alumina membrane pore surface wettability. The structural features were confirmed by scanning electron microscopy results.

Polarization properties of porous anodic alumina with Y-branched Cu nanowires

Porous anodic alumina （PAA） templates with branch structure are fabricated by the two-step anodic oxidation processes, and then the Y-branched Cu nanowires are synthesized in the templates using an alternating current （AC） deposition method. We observe the morphology image of the samples by scanning electron microscopy （SEM）, and measure the transmission spectrum and the polarization spectrum of the samples by the spectrophotometer. The results show that PAA films with Y-branched Cu nanowires have better transmittance in the near infrared region. An extinction ratio of 15 - 18 dB and an insertion loss of 0.1 - 0.4 dB are obtained in this region. Therefore PAA with Y-branched Cu nanowires can be used as a near-infrared micropolarizer, and this kind of micropolarizer would have a promising future in the field of photoelectricity integration.

A vivid Au-porous anodic alumina composite film with the inverted taper structure for label-free detection

Localized surface plasmon resonance(LSPR)has been widely used in medical detection because of its time effectiveness,noninvasiveness,high sensitivity,and relatively simple fabrication process.Porous anodic alumina(PAA)can be regarded as a plasma substrate for label-free detection due to its unique two-dimensional structure.In this work,a vivid Au-PAA composite film with the inverted taper structure was developed by multi-step anodic oxidation and pore-widening processes followed by magnetron sputtering with Au nanoparticles(AuNPs).The highly saturated and bright structural color was generated by the synergistic effect of photonic and plasmonic modes.Interestingly,various Au-PAA composite films with structural colors altering from purple to red were obtained via adjusting the height/diameter ratio of PAA.Benefiting from the inverted taper structure,light trap characteristics were effectively enhanced by increasing the incident light and reducing the diffuse light.In addition,a finite difference time domain(FDTD)model was proposed to predict the relationship between the reflectance peak and the height of the composite film,and the simulated data were in good agreement with the experimental results.As a proof of concept,labelfree detections of various reagents(water,ethanol,glycol,glycerol,and glucose),the concentration of glucose(refractive index sensitivity of 376 nm/RIU,RIU:refractive index unit),and thrombin(detection limit of 0.1×10^(-7)mol/L)were realized by the Au-PAA composite film.This vivid Au-PAA composite film provides a very powerful tool for in-situ label-free bio-detection.

TiO_2纳米管的模板法制备及表征

The template method for preparing nanostructures entails the synthesis of the desired material within the pores of a nanoporous membrane. In this work, TiO2 nanotubules of the anatase form have been synthesized by sol-gel chemical method using porous anodic alumina as the template. Transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, infrared spectroscopy（IR） and X-ray diffraction were used to investigate the structure and morphology of the TiO2 nanotubules. The results showed that the diameter and length of the obtained nanotubules were determined by the pore size and length of the PAA template. It was founded that through control of immersion time, both tubules and fibrils can be prepared; in addition, the wall thickness of the nanotubules can be varied at will. The result indicated that the sol particles absorbed preferably to the pore walls of the PAA membrane due to the fact that the pore walls were negatively charged and the TiO2 particles were positively charged.

TiO_2纳米管对十二烷基苯磺酸钠的光催化降解

以多孔阳极氧化铝为模板制备 Ti O2 纳米管。研究锐钛矿型 Ti O2 纳米管对降解低浓度的十二烷基苯磺酸钠的光催化作用。实验表明 ,与 Ti O2 膜相比 ,Ti O2

多孔阳极氧化铝的微观结构与气压的关系

为验证氧气析出对PAA孔道产生和发展的作用,深入探讨PAA的形成机理,本文分别研究了在真空下和常压下,铝在磷酸溶液中的阳极氧化过程,用SEM表征了不同气压下PAA孔道的微观结构。在低气压下制备PAA膜,因为氧气析出速度快,所以同样条件下得到的PAA的孔道比常压下的孔径大、孔壁薄。结果表明,"酸性溶解腐蚀孔洞"只发生在氧化膜的表层,而表层下方是规则的"氧气析出孔道";PAA孔道的生成和发展是内部氧气析出孔道和酸性溶解腐蚀孔洞贯通的过程,但起决定作用的是"氧气气泡模具效应"。

铜/多孔铝纳米有序阵列的近红外偏振特性研究

利用二次阳极氧化法在稀硫酸溶液中制备了不同孔径的多孔铝模板,并用交流电化学沉积的方法在多孔铝中合成了铜纳米线。测量了铜/多孔铝复合膜的透射光谱及偏振光谱。实验结果表明,这种含铜纳米线多孔铝膜微偏振器件在近红外光区有较好的透射率和消光比,且随着铜纳米线直径的增加,样品的透射率下降而其消光比却明显提高。通过分析得出,优化模板参数可制备出高效率的铜/多孔铝微偏振器。这种微偏振器件制备方法简单、效率高、造价低,在光电集成领域有着广泛的应用前景。

不同分枝结构多孔氧化铝膜的制备和光学特性

在阳极氧化铝的制备过程中,采用二次氧化方法,通过降低二次氧化过程中的电压,使之变为初始电压的1/n～1/2,得到了具有n个分枝结构的纳米孔径的氧化铝膜.利用岛津UV3101分光光度计测试了样品的透射光谱与偏振光谱.结果表明,在可见和近红外波段,线型孔径结构的多孔铝膜比Y型和枝状结构的多孔铝膜具有更好的透射性能,在偏振性能方面也有优势,更适合作含金属微偏振器件的膜板材料.

多孔阳极氧化铝的化学修饰及其应用于过氧化氢的测定

多孔阳极氧化铝经化学修饰后吸附细胞色素C,制备了过氧化氢生物传感器电极。多孔阳极氧化铝通过电化学和化学腐蚀阻挡层后,用两步无电沉积方法制备了纳米金修饰的多孔阳极氧化铝电极,再在含有L-半胱氨酸的细胞色素C的溶液中通过吸附制备细胞色素C电极。用循环伏安法和计时电流法测试细胞色素C电极的电化学性能及催化对过氧化氢的还原。结果表明,包覆的细胞色素C电极显示较好的稳定性,在扫描速度为80 mV/s时于-50 mV、-190 mV附近出现一对稳定的氧化还原峰。该电极对过氧化氢具有良好的电催化还原性能,在1.5×10-5 mol/L～4.8×10-4 mol/L浓度范围内,电流与浓度呈良好的线性关系。多孔阳极氧化铝经化学修饰后,可应用于生物传感器。

多通孔阳极氧化铝膜的制备

通过两步阳极氧化法由铝片制得高度有序的多孔氧化铝膜(PAA),采用高电压瞬时脉冲法分离出完整而独立的多通孔氧化铝模板。用SEM对其表面进行分析,结果表明用瞬时电压脉冲法可以很好地分离出完整的通孔膜,且膜质量很高。孔直径为40~50nm,孔间距为90~105nm,膜厚度为25μm左右,孔密度高达1.34×10^(10)个/cm^2。通过4次阳极氧化的时间电流密度曲线对比,表明两步阳极氧化可以刺得高度有序的PAA膜。

镀Ni超细孔径多孔阳极氧化铝模板的合成和特性

采用电沉积法制备的镀Ni超细孔径(5 nm)的多孔阳极氧化铝(PAA)薄膜系列,显示出鲜艳而多样的结构色。Ni沉积在超细孔径的多孔阳极氧化铝(UPAA)模板的表面上,形成了孔隙率很大的网状镀层。Ni层是由疏松的纳米点组成。这些纳米点平均长度约为46 nm,纵横比小于2。Ni纳米点吸收和散射了来自UPAA-Al界面反射的自然光,从而提高了UPAA模板的结构色饱和度。通过改变UPAA薄膜的厚度,可在自然光范围内精细调控样品的结构色。Ni/UPAA复合薄膜的矫顽力和方形度高达810 Oe和0.61。沉积的Ni层呈面心立方相和磁各向异性,其矫顽力基本符合一致转动模型。Ni/UPAA复合薄膜可应用于装饰、液体传感器、显示器和多功能防伪领域。