Formation and microstructures of unique nanoporous AAO films fabricated by high voltage anodization

Li, Yi; Ling, Zhiyuan; Hu, Xing; Liu, Yisen; Yi, Chul-Young

doi:10.1039/c1jm10781j

Cited by 41 publications

(30 citation statements)

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“…In addition, the t b can also be influenced by the formation and dehydration of aluminum hydroxides (e.g., Al(OH) 3 ) during high voltage anodization, which will lead to the oscillations of J a under CV mode. 19,49,52 Considering that J a is mainly related to the movement of ionic species, the nearly exponential decrease of J a can be explained reasonably by the diffusion-limited aluminum anodization process at the pore bottom. 14,19,49,52,53 When an ending J a of 100 A m −2 is applied (Figures 4c and 4d), separated clusters of structural cells can be observed at the barrier layer surface of the sample, which is different from the larger interlinked clusters shown in Figures 1a and 1b.…”

Section: Resultsmentioning

confidence: 97%

“…48 It has been known that the competitive growth of AAO structural cells can be induced by a high enough U a during anodization, thus resulting in the initiation of competitive growth starting site (CGSS, the arrows in Figure 1c, 1f and 1i) in the AAO film. 48,49 Accordingly, separated clusters of structural cells can be formed around CGSS as their central growing site, and each of those larger clusters may contain more than one CGSS (Figures 1d-1f, 500 V). When a higher U a of 600 V is applied, the competitive growth process will be further enhanced, and more CGSS can be formed keeping other anodization conditions unchanged.…”

Section: Resultsmentioning

confidence: 97%

“…14,24,49 However, ξ has an opposite tendency, which can be attributed to the formation and dehydration of aluminum hydroxides (e.g., Al(OH) 3 ) during high voltage anodization. 49 It worth mentioning that more Al(OH) 3 can be formed under certain anodization conditions with a higher U a . 49,52 Considering that Al(OH) 3 has a relatively small dissociation energy (3.80 kcal mol −1 ), it will dehydrate easily during high voltage anodization thus leading to volume contraction of the AAO cell walls.…”

Section: Resultsmentioning

confidence: 99%

“…49 It worth mentioning that more Al(OH) 3 can be formed under certain anodization conditions with a higher U a . 49,52 Considering that Al(OH) 3 has a relatively small dissociation energy (3.80 kcal mol −1 ), it will dehydrate easily during high voltage anodization thus leading to volume contraction of the AAO cell walls. 16,49,52 Accordingly, it is not surprising to see that ξ decreases with U a (Figure 3).…”

Section: Resultsmentioning

confidence: 99%

“…49,52 Considering that Al(OH) 3 has a relatively small dissociation energy (3.80 kcal mol −1 ), it will dehydrate easily during high voltage anodization thus leading to volume contraction of the AAO cell walls. 16,49,52 Accordingly, it is not surprising to see that ξ decreases with U a (Figure 3). In other words, the influence of U a on ξ under extremely high U a cannot be ignored, which is different from that obtained by hard anodization under relatively lower U a of 110-150 V. 14 The influence of J a and ethanol adding on submicron/micron structures.-Considering that aluminum anodization processes and structural parameters of porous AAO films can also be influenced by J a to a certain extent, the sample with a different J a of 100 A m −2 has been fabricated under 600 V for a comparative study (Figures 4a-4d).…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

A Facile Method for Controllable Fabrication of Porous Anodic Aluminum Oxide Templates with Multiple-Scale Structures

Jin

Qin

et al. 2015

J. Electrochem. Soc.

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Porous anodic aluminum oxide (AAO) templates with diverse nano/submicron/micron multiple-scale structures have been fabricated by a facile and controllable two-step anodization process. The first step anodization has been achieved by using a simple competitive growth process with high anodization voltage (U a ) in ethanol-oxalic acid mixture electrolytes. The effects of U a (300-600 V), anodization current density (J a , 100-200 A m −2 ), and the proportion of ethanol adding (0.3 M oxalic acid : ethanol = 1 : 1, 3 : 2, V/V) on the submicron/micron structures of AAO templates have been investigated in detail. The second step anodization has been conducted under relatively lower U a of 30 V and 40 V, respectively. The effects of U a , etching process, and anodization time on the nanostructures of as-fabricated porous AAO templates have been studied carefully. In addition, related intrinsic formation mechanisms have also been investigated. Based on these quantitative experimental results, the fabrication of multiple-scale porous AAO films with diverse nano/submicron/micron structures can be more controllable and designable, facilitating their practical applications in simple template synthesis of complex multiple-scale functional materials.Anodic aluminum oxide (AAO) films prepared by aluminum anodization have been investigated and used in numerous fields for more than 150 years. 1-24 In 1953, Keller et al. investigated the structural features of porous type AAO films in detail with the electron microscope and proposed a corresponding structural model. 5 Since then, porous AAO films which contain a large number of nanopores have attracted considerable attention. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] In 1995, Masuda et al. firstly proposed a pre-patterning fabrication process which contains the first anodization for forming highly ordered dimples on the aluminum surface, and the second anodization for obtaining ideally ordered porous AAO films. 12,13 At present, they have become one of the most commonly used nanoporous templates for the fabrication of diverse nanomaterials (e.g., nanowire, nanotube, and nanodot) because of their apparent advantages, such as good reproducibility, adjustable pore size, and controllable film thickness, etc. 25-35 Moreover, they can also be used as functional materials for many applications: e.g., biotechnology, photonics, sensors. [36][37][38][39][40] Nowadays, although porous AAO films can be applied in many practical fields, there are still some shortcomings which greatly limit their applications: most of the fabricated porous AAO films have a simple honeycomb-like microstructure, and their pore size is typically limited to nanoscale or submicron scale. Based on these structural features, it is difficult for their template synthesis of functional materials with micron scale or nano/submicron/micron multiple-scale structures. Over the last decade, tremendous research has been focused on the development of multiple-scale materials which have become a h...

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

A Facile Method for Controllable Fabrication of Porous Anodic Aluminum Oxide Templates with Multiple-Scale Structures

Jin

Qin

et al. 2015

J. Electrochem. Soc.

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Mechanisms of Nanoporous Alumina Formation and Self-organized Growth

Ling

2015

Nanoporous Alumina

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The synthesis of nanoporous alumina based on anodization process is a field of active research. In this chapter, some fundamental scientific topics toward formation mechanisms of nanoporous alumina will be discussed in detail.(1) The intrinsic mechanisms of mild and hard anodization processes: the definition of mild anodization (MA) and hard anodization (HA); the critical condition between MA and HA processes. (2) The origins of self-ordering phenomenon: the structure models of nanoporous alumina; the influence of electrical field and internal stress. (3) The growth models of nanoporous alumina: the classical growth models of nanoporous alumina; the advantages and disadvantages of present models; the physical and chemical processes during aluminum anodization. (4) The intrinsic relationship between anodization conditions and anodization processes: the influence of anodization voltage and current density; the influence of electrolyte system; the influence of other anodization conditions. (5) Controllable fabrication of nanoporous alumina: the relationship between anodization conditions and structural parameters (e.g., interpore distance, pore size); fabrication of regular nanoporous alumina (i.e., with highly ordered pores); fabrication of nanoporous alumina with complex pore structure. In addition to nanoporous alumina, the findings and conclusions in this chapter may also be applied in other valve metal anodization processes (e.g., Ti, Zr, W anodization).

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Fabrication of porous anodic aluminum oxide by hybrid pulse anodization at relatively high potential

2013

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Formation and microstructures of unique nanoporous AAO films fabricated by high voltage anodization

Cited by 41 publications

References 37 publications

A Facile Method for Controllable Fabrication of Porous Anodic Aluminum Oxide Templates with Multiple-Scale Structures

A Facile Method for Controllable Fabrication of Porous Anodic Aluminum Oxide Templates with Multiple-Scale Structures

Mechanisms of Nanoporous Alumina Formation and Self-organized Growth

Fabrication of porous anodic aluminum oxide by hybrid pulse anodization at relatively high potential

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