Properties of porous anodic aluminum oxide films as membranes.

Itaya, Kingo; Sugawara, Shizuo; Arai, Kunio; Saito, Shozaburo

doi:10.1252/jcej.17.514

Cited by 121 publications

(62 citation statements)

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“…Itaya et al demonstrated that gas permeation through the channels in an AAO film obeys Kunudsen flow and the film can be used for the ultrafiltration of both aqueous and nonaqueous solutions of organic polymers. 16 Many other researchers have also examined the applicability of an AAO film as a membrane filter. [17][18][19][20][21][22][23] Now it is commercially available as an inorganic membrane for microfiltration.…”

Section: Synthesis Of Various Types Of Carbon Nanotubesmentioning

confidence: 99%

Synthesis of Various Types of Nano Carbons Using the Template Technique

Kyotani¹

2006

Bulletin of the Chemical Society of Japan

101

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Using uniform nanochannels of an aluminum anodic oxide film as a template, uniform and unique multiwalled carbon nanotubes can be synthesized with a selectivity of 100%. This technique allows one to precisely control the diameters and the length of nanotubes. Moreover, it is possible to chemically modify only the inner surface of carbon nanotubes and to prepare carbon nanotubes with a double coaxial structure of heteroatom-doped multiwalls. The test tube like carbon prepared by this technique was found to be dispersible in water without any post treatment. In addition to this one-dimensional approach, unique microporous carbon can be prepared by the template technique using zeolite Y. The resulting microporous carbons are characterized by their regular ordering, originating from the regularity of the parent zeolite. When the synthesis conditions were optimized, the specific surface area and the micropore volume of the zeolitetemplated carbon reach more than 4000 m 2 g À1 and 1.8 cm 3 g À1 , respectively. This review introduces such a templatemediated approach and highlights how useful and versatile the template technique is for the production of nano carbons.Carbon is an element with a unique ability to bond with itself principally via sp 3 (diamond-like) and sp 2 (graphite-like) hybridization. This versatility gives rise to a rich diversity of structural forms of solid carbon. Most of the materials dealt with in carbon science and industry are considered to be composed of mainly large polycyclic aromatic molecules. The differences in the shape of such macromolecules and the way the molecules assemble (how they stack and how they are connected to one another) again lead to an immense variety of possibilities. If one could control the shape of the macromolecules and the state of their assemblage at the nanometer level, it would be possible to prepare carbon materials with a unique nano structure, thereby expecting novel and useful characteristics from the structure. Such control is, however, a very difficult task, because the nano structure of carbon materials is not uniform by nature, except for perfect graphite and diamond. To illustrate, a drawing of the molecular structure of activated carbon is shown in Fig. 1, where many curved polycyclic aromatic molecules with different sizes and shapes are stacked and connected in very complicated ways, which is quite different from the uniform ordered porous structure of zeolite materials. It is easily understood from this molecular model that control of the shape and the position of each macromolecule in the model is very difficult and essentially impossible. For the ultimate control of the carbon nano structure, it is desirable to build up a carbon structure from small building blocks, i.e., synthesize the structure from small organic molecules using techniques developed in the field of organic synthesis. However, the organic syntheses of fullerenes and carbon nanotubes have not been achieved yet, even by using cutting-edge technology. One of the most powerful and pro...

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Section: Synthesis Of Various Types Of Carbon Nanotubesmentioning

confidence: 99%

Synthesis of Various Types of Nano Carbons Using the Template Technique

Kyotani¹

2006

Bulletin of the Chemical Society of Japan

101

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“…A promising approach to fabricate nanowire systems is to fill an array of nanochannels with the media of interest. Porous anodic alumina, [1][2][3] which has hexagonally packed nanometer-sized channels, is one such possible host template. Besides its desirable geometry, the wide band gap energy of alumina makes it an excellent host material for quantum wires.…”

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confidence: 99%

Bismuth quantum-wire arrays fabricated by a vacuum melting and pressure injection process

1998

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Ultrafine bismuth nanowire arrays were synthesized by injecting its liquid melt into nanochannels of a porous anodic alumina template. A large area (1 cm 3 1.5 cm) of parallel wires with diameters as small as 13 nm, lengths of 30-50 mm, and packing density as high as 7.1 3 10 10 cm 22 has been fabricated. X-ray diffraction patterns revealed these nanowires, embedded in the insulating matrix, to be essentially single crystalline and highly oriented. The optical absorption spectra of the nanowire arrays indicate that these bismuth nanowires undergo a semimetal-to-semiconductor transition due to two-dimensional quantum confinement effects.Highly regular metal and semiconductor nanowire arrays embedded in a dielectric matrix have attracted a great deal of research attention because of their potential applications in electronic and optical devices and promise for studying one-dimensional (1D) quantum properties. The quantum confinement of carriers in two dimensions will significantly change their electronic energy states and make the properties of these 1D systems very different from their bulk counterparts. A promising approach to fabricate nanowire systems is to fill an array of nanochannels with the media of interest. Porous anodic alumina, 1-3 which has hexagonally packed nanometer-sized channels, is one such possible host template. Besides its desirable geometry, the wide band gap energy of alumina makes it an excellent host material for quantum wires. Anodic alumina has previously been used to synthesize a variety of metal and semiconductor nanowires, such as Ni, Pd, Au, Pt, and CdS, through chemical or electrochemical processes. [4][5][6][7] However, the diameters of those nanowires have not reached the quantum confinement regime. In order to exhibit strong quantum confinement characteristics, the wire diameter should be smaller than the exciton diameter, which is given by d ex 2eh 2 (m 21 e 1 m 21 h )͞e 2 , where e is the static dielectric constant, and m e and m h are the effective masses of electrons and holes, respectively. Bismuth, which is a semimetal and has a very small electron effective mass (m e ഠ 0.014m 0 at the band edge along a) Author to whom correspondence should be addressed. the trigonal direction, and m e ഠ 0.0036m 0 for heavy electrons along the bisectrix direction), is considered a good candidate to study quantum confinement effects in the 1D system. Our theoretical calculations estimate that Bi makes a transition from a semimetal to a 1D semiconductor at a wire diameter of about 45 nm or 81 nm if the wire is oriented along the trigonal direction or the bisectrix direction, respectively. 8In this paper, Bi quantum-wire arrays were fabricated by a novel vacuum melting and pressure injection technique which can produce continuous, dense nanowire arrays, as required by many practical electronic applications. High-pressure injection of molten metal has been used to fill a single glass nanotube, 9 and more recently, porous anodic alumina having channel diameters larger than 200 nm. 10 The injec...

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“…The electrochemical cell of anodizing consists of cathode, anode (the metal substrate to be converted to metal oxide) and direct current (DC) power supply. The anodic aluminum oxide thin film starts to grow at the anode (aluminum surface) as the anodic current or voltage is applied [1,2].…”

Section: Introductionmentioning

confidence: 99%

Effect of the removal of the barrier layer period in productive process for anodic alumina membrane

Daryakenari¹,

Zohrabi²,

Daryakenari³

2016

Nanosystems: Phys. Chem. Math.

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An anodic alumina membrane (AAM) is produced using two-step anodizing by using various types of acidic electrolytes, such as sulfuric acid, phosphoric acid and oxalic acid. Holes are characterized by hexagonal structure with diameters ranging from 40 to 420 nm. Heat and chemical stability also regular formed holes are made the membranes appropriate for using in gas separating process, drug delivery and applicant for fuel cell membrane. Detaching of membrane from the aluminum base is the most important stage of the membrane production process. In this research, initially, the aluminum base layer was removed with the use of CuSO 4 and HCl. In secondary step, barrier layer at the end of the holes were removed with phosphoric acid solution. The aim of this work is to analyze the effect of time on the barrier layer removal process.

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Properties of porous anodic aluminum oxide films as membranes.

Cited by 121 publications

References 1 publication

Synthesis of Various Types of Nano Carbons Using the Template Technique

Synthesis of Various Types of Nano Carbons Using the Template Technique

Bismuth quantum-wire arrays fabricated by a vacuum melting and pressure injection process

Effect of the removal of the barrier layer period in productive process for anodic alumina membrane

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