多孔阳极氧化铝模板制备的研究进展

多孔阳极氧化铝(PAA)模板在制备纳米材料、光谱材料、磁性材料、生物传感材料、太阳能电池材料等领域有着极为广泛的应用。实现多孔阳极氧化铝模板的孔径、孔间距、氧化层厚度等参数的可控制备是获得最佳性能材料的关键。概述了近年来多孔阳极氧化铝模板制备的研究进展,简要介绍了在电化学方法制备条件下各种工艺因素对模板形貌的影响,并综述了利用多孔阳极氧化铝作为模板合成纳米材料的几种方法。     

草酸溶液中制备大孔间距的通孔PAA模板

为了制备规则有序、大孔间距的多孔阳极氧化铝(PAA)模板,通过在传统的草酸溶液中添加乙醇以及阶梯升压的方法,使草酸溶液的耐压从原来的40V左右提高至150V,制备了大孔径(约200nm)、大孔间距(约350nm)的有序PAA模板。详细研究了这种高电压氧化得到的具有较厚阻挡层PAA模板的通孔工艺,实验结果表明,在5%(质量分数)磷酸水溶液中30℃下浸泡180min,可以得到有序的PAA通孔模板,首次计算了阻挡层的减薄速率为约1.26nm/min。     

多孔阳极氧化铝模板的影响因素

近年来,随着纳米技术的发展,研究制备具有纳米孔结构的氧化铝多孔膜越来越受到人们的关注.多孔阳极氧化铝(porous anodic alumina,PAA)薄膜具有易于制备,工艺简单,且价格便宜等诸多优点而被广泛地应用于各个领域.为了制备出性能更加优越的PAA模板,各国学者都对其进行了一些研究.但目前的研究大都不系统,针对这一问题,作者进行了大量的实验,通过实验总结出了PAA模板的主要影响因素,并分别讨论了这些影响因素对模板的有序度、孔密度和模板厚度的影响.     

多孔阳极氧化铝模板上电子束蒸发沉积TiO_2

以硫酸、草酸溶液为电解液,采用二次阳极氧化法制备了初始孔径在20~120 nm、孔间距在40~250 nm、孔深在200 nm~80μm范围内的具有高度有序纳米孔阵列的多孔阳极氧化铝(porous anodic alumina,PAA)模板。以PAA模板为基片,采用真空电子束蒸发的方法在PAA模板上制备了具有高度有序的TiO2纳米点阵列。利用场发射扫描电子显微镜和原子力显微镜对其形貌进行了表征。研究表明,所形成的TiO2纳米点阵列具有同其基底PAA模板相同的序列结构。对TiO2纳米点阵列的生长形成机理进行了讨论。     

模板法制备中空结构材料的研究进展

中空结构材料具有低密度、高比表面积、可以容纳客体分子等特点被广泛用于环境保护、生物医药、电子等领域。模板法具有简单、重复率高、预见性好等诸多优点, 在制备中空结构材料的过程中被广泛采用。根据所使用模板性质的不同, 模板法又可分为传统模板法和自模板法两类。本文对模板法制备中空结构材料的研究进行了综述, 首先阐述了硬模板法和软模板法两种传统模板法制备中空结构材料的研究进展, 并在此基础上重点综述和评价了奥斯特瓦尔德熟化法、柯肯达尔效应法、电化学置换法和化学刻蚀法四种自模板法制备中空结构材料的研究进展, 最后, 对模板法制备中空结构材料的发展前景进行了展望。     

模板法制备TiO2的研究进展

作为近些年来倍受关注的过渡族金属氧化物,TiO2被广泛应用于诸如光催化、染料敏化太阳能电池、气体传感器等多个领域。与合成TiO2的传统方法相比,模板法有着反应条件温和、产物形貌尺寸易控、操作简单等优点。将模板分为非生物模板与生物模板两大类,分别综述了以这两大类模板制备TiO2的最新进展,并且介绍了其在各个领域的应用,最后展望了模板法制备TiO2未来的发展方向,以期为今后模板法制备TiO2的工作提供参考与指导。     

聚乙二醇模板剂制备介孔材料的研究进展

聚乙二醇作为模板剂被广泛用于介孔材料的制备。介绍了使用单一聚乙二醇模板剂合成硅基、非硅基、复合类介孔材料的研究工作,探讨了聚乙二醇与表面活性剂、非表面活性剂类物质作复合模板剂制备介孔材料的方法。综述了聚乙二醇单一模板剂及复合模板剂制备介孔材料的机理。     

纳米多孔金属的制备方法研究进展

综述了去合金化法和模板法2种制备纳米多孔金属材料的方法.以多孔金的制备为代表.进行了较详细的介绍.比较2种制备方法得出,模板法简单方便、可控性良好,应用更加广泛;模板法包括AAO模板/PC模板法、蛋白石/反蛋白石结构模板法以及氢气模板法等.通过模板法能够获得分布有序的多孔结构,且孔间的联通性较好,是一种制备纳米多孔材料的重要方法.     

强发光多孔氧化铝模板

以氧化铝模板(PAA)为母体,通过浸泡Cr2(SO4)3溶液掺入三价Cr离子,将掺杂的PAA煅烧使其晶化,不同的煅烧温度形成不同的相.随着α相的形成,材料就会有极强的光致发光,发光波长在692nm附近,而且线宽很窄.通过适当控制煅烧温度,微量存在的γ相仍然可以使PAA保持其固有的纳米孔洞结构,而大量的α相已经使PAA具有了良好的光致发光性能.这种氧化铝发光模板可以用来制备纳米复合功能材料.     

矿物模板法制备多孔炭材料研究进展

与传统的炭材料合成方法相比,模板法在孔径控制方面优势突出,是一种制备多孔炭的简易方法。天然矿物具有微米、纳米孔道结构,而且资源丰富、价格低廉,为制备多孔炭材料提供了理想模板。综述了常用矿物模板的性质以及天然矿物为模板合成炭材料的研究进展,指出了制备模板炭材料过程中存在的问题,并对其发展前景进行了展望。     

Lithography-free in situ Pd contacts to templated single-walled carbon nanotubes

We report a metalization technique for electrically addressing templated vertical single-walled carbon nanotubes (SWNTs) using in situ palladium (Pd) nanowires. SWNTs are synthesized from an embedded catalyst in a modified porous anodic alumina (PAA) template. Pd is electrodeposited into the template to form nanowires that grow from an underlying conductive layer beneath the PAA and extend to the initiation sites of the SWNTs within each pore. In this way, individual vertical channels of SWNTs are created, each with a vertical Pd nanowire back contact. Further Pd deposition results in annular Pd nanoclusters that form on portions of SWNTs extending onto the PAA surface. Two-terminal electrical characteristics produce linear I-V relationships, indicating ohmic contact in the devices.     

Emulsion templating of poly (acrylic acid) by ammonium hydroxide/sodium hydroxide aqueous mixture for high-dispersed hollow silica nanoparticles

A water-in-oil (W/O) emulsion, in which the water phase including poly (acrylic acid) (PAA), ammonium hydroxide (NH₃ aq.), and sodium hydroxide aqueous solutions (NaOH aq.) dispersed in ethanol (EtOH), was proposed for producing hollow silica nanoparticles. The PAA molecules with the NH₃-NaOH mixture are insoluble in EtOH and can be a template. When tetraethoxysilane (TEOS) is added as a silica source, a silica shell is formed on the PAA-NH₃-NaOH template to form a core-shell particle and the addition of water removes the template to form hollow silica nanoparticles. The optimum volume ratio of 25% NH₃:1.0 M NaOH was 2:1 to obtain high-dispersed hollow silica nanoparticles. A thermogravimetric analysis indicated that the condensation force of the PAA molecules in the PAA-NH₃-NaOH template is similar to that in the PAA-NH₃ template. The small angle X-ray scattering (SAXS) analysis also showed that the electron densities in the PAA-NH₃-NaOH and PAA-NH₃ templates are similar. In the proposed PAA-NH₃-NaOH system, NH₃ aq. mainly contributes to form PAA condensation by an ionic interaction and NaOH aq. preferentially work as a sol-gel catalyst for the fast silica coating on the template surface.     

Preparation and Analysis of Porous Anodic Alumina Template on Silicon Substrate

Porous anodic alumina (PAA) template is widely used to prepare ordered nanostructure materials. But conventional PAA templates have been restricted for application in micro-electro-mechanical systems (MEMS) technology due to limitations such as shape and brittleness. In this article, a novel process of fabricating alumina porous template based on silicon wafer is described. Porous alumina films were formed by two-step anodization of aluminum layers sputter deposited on silicon wafer. The pore diameters range from 80 to 100 nm. The Pilling–Bedworth ratio of Al/Al₂O₃ was measured and calculated. Thickness of PAA template can be precisely controlled. This research provides an effective tool to nanofabrication in MEMS technology.     

Fabrication of mesoporous titanium oxide nanotubes based on layer-by-layer assembly

Titanium oxide (TiO2)/polyacrylic acid (PAA) composite nanotubes were firstly fabricated through the sol-gel process of titanium alkoxide in the inner pores of alumina template followed layer-by-layer assembly with polyacrylic acid (PAA). Mesoporous TiO2 nanotubes could be obtained after the removal of PAA component by calcination and etching of the template with concentrated sodium hydroxide aqueous solution. The surface area of as-prepared porous TiO2 nanotubes was measured as twice larger than that of the conventional TiO2 nanotubes and the pore diameter in the wall of the tubes is several nanometers. Such assembled mesoporous nanotubes can serve as carriers for catalysis release and biomolecules.     

铜纳米线阵列的模板组装

采用电解法溶解多孔阳极氧化铝(PAA)模板的阻挡层,用直流电沉积的方法在模板中组装了铜纳米线阵列.分别用扫描电镜和X射线衍射表征铜纳米线阵列的形貌和晶体结构,用电化学法表征了铜纳米线阵列的电催化性能.结果表明,PAA去阻挡层后,伏安图上出现一个阳极氧化峰.恒电位沉积的铜纳米线直径为22nm,沿(111)晶面择优取向.铜纳米线阵列电极能催化亚硝酸根的还原,其催化电流比本体铜电极上大2倍,峰电位正移80mV.纳米铜阵列电极可用于亚硝酸盐的电化学检测.     

Screening the Insecticidal Efficacy of Nano ZnO Synthesized via in-situ Polymerization of Crosslinked Polyacrylic Acid as a Template

Nano zinc oxide (ZnO) is a very useful and important material in many industrial and biological applications. In the present work, ZnO was synthesized by post thermal degradation of the precursor "zinc acetate di-hydrate" templated in crosslinked polyacrylic acid (PAA). The crosslinked PAA template was prepared through an in-situ polymerization process adopted in presence of ammonium per sulphate, as an initiator, and N, Nmethylene bis-acrylamide as the crosslinker. Variation of preparation parameters and their impact on the oxide stoichiometry, crystal structure, crystallite size and surface texture of the oxide were investigated. Energy dispersive X-ray technique (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were convincingly used to reveal the oxide structural features and characteristics. The performed bioassay tests indicated the efficacy of this method of preparation to produce nano ZnO with novel insecticidal activity against the greater wax moth, Galleria mellonella.     

Templated growth of tungsten oxide micro/nanostructures using aerosol assisted chemical vapour deposition

Porous anodized alumina (PAA) and macroporous silicon (MS) substrates have been used to template the growth of tungsten oxide via aerosol assisted chemical vapour deposition from the precursor tungsten hexaphenoxide. The results show that thin PAA substrates have potential as templates for growing microstructured tungsten oxide films and MS substrates cause the growth of ‘grids’ of polycrystalline tungsten oxide.     

Phase development and structural characterization of calcium phosphate ceramics-polyacrylic acid nanocomposites at room temperature in water-methanol mixtures

Calcium phosphate ceramics (CPCs) were prepared via an in-situ formation in the presence of polyacrylic acid (PAA) polymer under water-methanol (WM) mixture at room temperature. The PAA polymer was employed as both structure-directing agent and crystallization retardant to manipulate the development of resulting CPCs nano-crystallites which are observed to show a core-shell configuration with a thin layer of PAA molecules. A resulting phase evolution map with respect to the developing phases of calcium-deficient hydroxyapatite (CDHA), -tricalcium phosphate (-TCP), and an intermediate amorphous calcium phoshate (ACP) that were structurally and spectroscopically identified, was constructed in terms of fractions of water-to-methanol proportions and concentration of PAA. It is found that for the solutions in both water-rich and methanol-rich regions, pure CDHA and -TCP instead of intermediate ACP phase can be developed irrespective of the concentration of PAA, respectively. For conditions in between, i.e., with methanol fractions of 15%–90%, ACP appeared only when the PAA fell in a limited concentration range.     

Assemblies of carbon nanotubes and unencapsulated sub-10-nm gold nanoparticles

The development of assemblies consisting of unencapsulated, sub-10-nm gold particles attached to individual carbon nanotubes (CNTs) with diameters of 2 nm is described. The assemblies are formed on the surface of a porous anodic alumina (PAA) template on which the CNTs (single- or double-walled) are grown by plasma-enhanced chemical vapor deposition. The Au nanoparticles are formed through an indirect evaporation technique using a silicon nitride membrane mask, and diffuse along the PAA surface into the regions containing CNTs. The nanoparticles bind relatively strongly to the CNTs, as indicated by observations of nanoparticles that are suspended over pores or that move along with the CNTs. This approach may provide a new method to functionalize CNTs for chemical or biological sensing and fundamental studies of nanoscale contacts to CNTs.     

Structure-dependent adhesion and friction on highly ordered metallic nanopore membranes

Highly ordered metallic nanopore membranes are fabricated by direct deposition of nickel on typical porous anodic alumina (PAA) templates. The large-area uniform nanopore arrays of the PAA templates are accurately transferred to the metallic nanopore replicas, depending on the thickness of the deposited metal and the pore size of the base template. We demonstrate the ready tunability of the pore size and reproducibility of the metallic nanopore structure in a wide range of pore sizes. The adhesion and friction characteristics of the metallic replicas are studied according to the pore size using atomic force microscopy (AFM). As the pore diameter increases, the friction coefficients increase nonlinearly, and the adhesive forces scarcely change. These characteristics are understood in terms of the structural properties of the replicas, specifically the surface morphology and the real contact area. Initial pore formation from a flat thin film reduces the adhesive force by up to four times.