Fabrication of Anodic Nanoporous Alumina via Acetylenedicarboxylic Acid Anodizing

Nishinaga

et al. 2014

Electrochimica Acta

The self-ordering behavior of anodic porous alumina that was formed by anodizing in selenic acid electrolyte (H 2 SeO 4 ) at various concentrations and voltages was investigated with SEM and AFM imaging. A high purity aluminum foil was anodized in 0.1-3.0 M selenic acid solutions at 273 K and at constant cell voltages in the range of 37 to 51 V. The regularity of the cell arrangement increased with increasing anodizing voltage and selenic acid concentration under conditions of steady oxide growth without burning. Anodizing at 42-46 V in 3.0 M selenic acid produced highly ordered porous alumina. By selective dissolution of the anodic porous alumina, highly ordered convex nanostructures of aluminum with diameters of 20 nm and heights of 40 nm were exposed at the apexes of each hexagonal dimple array. Highly ordered anodic porous alumina with a cell size of 102 nm from top to bottom can be fabricated by a two-step selenic acid anodizing process, that includes the first anodizing step, the selective oxide dissolution, and the second anodizing step.Key words: Aluminum; Anodizing; Anodic Porous Alumina; Selenic Acid IntroductionBarrier anodic oxide films and porous anodic oxide films on aluminum have been widely investigated by many researchers in the fields of surface finishing [1][2][3], electrolytic capacitor application [4][5][6], and micro-and nano-structure fabrication [7][8][9]. Recently, highly ordered anodic porous alumina with a cell size on the scale of 10-100 nm has been studied for potential use in various ordered-nanostructure applications [10][11][12][13][14][15][16][17][18][19][20][21]. Anodic porous alumina is typically fabricated on an aluminum substrate using electrochemical anodizing (or anodization) [22][23][24][25][26]. In several acidic electrolyte solutions, the porous alumina fabricated by anodizing is self-ordered when prepared at the appropriate electrochemical conditions, including appropriate concentrations, temperatures, and voltages (or electrochemical potentials) [27][28][29][30] [50], and acetylenedicarboxylic (HOOC-C≡C-COOH) [51] acids have also been reported as electrolytes used to fabricate porous alumina that has characteristic nanostructure morphologies.In addition to these acidic electrolytes, alkaline and neutral solutions used for porous alumina fabrication were reported by several research groups. Takahashi et al. reported that a porous anodic oxide film could be formed by anodizing in an H 3 BO 3 /Na 2 B 4 O 7 neutral borate solution at a high temperature [52]. Baron-Wiechec et al. investigated aluminum anodizing in a borax (Na 2 B 4 O 7 ) solution at 333 K and successfully obtained porous alumina [53]. Noguchi et al. investigated the anodizing behavior of aluminum in propylenediamine and choline alkaline solutions containing ammonium fluoride, ammonium tartrate, ammonium carbonate, and ammonium tetraborate, and obtained anodic porous alumina with nanopores that were 10-150 nm in diameter [54]. However, it is difficult to form a highly ordered porous alumina by anodiz...

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Self-Ordering Behavior of Anodic Porous Alumina via Selenic Acid Anodizing

Nishinaga

et al. 2014

Electrochimica Acta

“…Additional dicarboxylic acids with a large molecular structure, malonic and tartaric acids, for the fabrication of anodic porous alumina were reported by Ono et al, and self-ordering was achieved by anodizing with these acids for 300 and 500 nm intervals, respectively. 22 Recently, we reported several novel electrolytes for the formation of anodic porous alumina: selenic, 23,24 acetylenedicarboxylic, 25 squaric, 26 croconic, 27 rhodizonic, 27 ketoglutaric, 28 acetonedicarboxylic, 28 and etidronic acids. 29,30 Particularly, etidronic acid anodizing exhibited large-scale self-ordering behavior measuring 530-670 nm in cell diameter.…”

mentioning

confidence: 99%

Self-Ordered Aluminum Anodizing in Phosphonoacetic Acid and Its Structural Coloration

Takenaga

ECS Solid State Letters

2015

Self Cite

Ordered anodic porous alumina with large-scale periodicity was fabricated via phosphonoacetic acid anodizing. Aluminum specimens were anodized in a 0.1-0.9 M phosphonoacetic acid solution under various electrochemical operating conditions, and optimum anodizing at 205-225 V exhibited self-ordering growth of the porous alumina. These self-ordering voltages during phosphonoacetic acid anodizing filled an undiscovered vacant region in the linear relationship between the self-ordering voltage and the cell diameter. The nanostructured aluminum surface formed via self-ordering phosphonoacetic acid anodizing produced a bright structural coloration with a visible light wavelength of 500-700 nm, which is useful for optical nanoapplications. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0021508ssl] All rights reserved. Self-ordered anodic porous alumina possesses a well-defined periodic porous structure with numerous nanopores that have high aspect ratios. [1][2][3] This characteristic nanoporous material is widely used for various novel nanoapplications, including electronic, optical, and sensing devices. [4][5][6][7][8][9][10][11][12] Ordered porous alumina can be fabricated by electrochemical anodizing in several acidic electrolyte solutions under appropriate experimental conditions such as concentration and applied voltage. The periodical size of the obtained ordered porous alumina, defined as the "cell size" or "interpore distance", is typically determined by the electrolyte species used.2,3,13 In self-ordered anodizing, the regularity of the pore arrangement in the porous structure can be accurately determined by a quantitative analysis based on Fourier transformation.14-19 Sulfuric, oxalic, and phosphoric acids were found early and have been commonly used as the standard self-ordering electrolytes to date. 13,20,21 However, the cell size of these ordered porous alumina is limited to the following narrow nanometer-scale regions: 50-60 nm in sulfuric acid, 100 nm in oxalic acid, and 405-500 nm in phosphoric acid.13 Therefore, the identification of novel electrolytes for self-ordered porous alumina with different cell sizes has been a recent challenge to extensively expand the nano-periodicity. Additional dicarboxylic acids with a large molecular structure, malonic and tartaric acids, for the fabrication of anodic porous alumina were reported by Ono et al., and self-ordering was achieved by anodizing with these acids for 300 and 500 nm intervals, respectively. Particularly, etidronic acid anodizing exhibited large-scale self-ordering behavior measuring 530-670 nm in cell diameter. Eti...

“…Cyclic oxocarbonic acids such as squaric [24], croconic, and rhodizonic [25] acid were very recently determined to be suitable organic electrolytes for fabricating porous alumina, although the details of the growth behavior are still unknown. Carboxylic acids can also be employed as suitable electrolytes for fabricating porous alumina, including oxalic [26,27], malonic [28,29], citric [30,31], malic [32], acetylenedicarboxylic [33], tartaric [34,35], tartronic [36], glycolic [37], and formic [38] acid. Because the nanostructural features and chemical properties of anodic porous alumina are determined and limited by the electrolyte used [39], the discovery of a new suitable electrolyte would expand the applicability of porous alumina.…”

Section: Introductionmentioning

confidence: 99%

Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

Nakajima

Applied Surface Science

2014

The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films.Keywords: Aluminum; Anodizing; Glutaric Acid; Ketoglutaric Acid; Acetonedicarboxylic Acid IntroductionAnodic porous alumina with numerous vertical, nano-scale pores can easily be fabricated via aluminum anodizing in several types of acidic aqueous solutions and has been widely applied in the fields of corrosion protection and electronic applications [1][2][3][4][5][6]. In particular, the development of highly ordered anodic porous alumina, which is fabricated via self-ordering and two-step anodizing under appropriate electrochemical conditions, has expanded the applicability of porous alumina [7]. Accordingly, plasmonic devices [8], antireflection polymer structures[9], optical devices [10], and high-density recording media [11] have been successfully fabricated through the combination of methods for developing highly ordered anodic porous alumina and other nanostructure fabrication techniques.The electrolyte species used for anodic porous alumina fabrication can be specifically classified into the following three groups: inorganic, organic cyclic oxocarbonic, and organic carboxylic acids. It is a well-known experimental fact that anodic porous alumina can be formed by anodizing in these acidic electrolytes, which provide low acid dissociation constants. To date, sulfuric [12][13][14][15][16], selenic [17,18], phosphoric [19,20], and chromic[21] acids have been reported as useful inorganic electrolytes for fabricating anodic porous alumina. The ideal cell arrangement of porous alumina can be achieved via sulfuric, selenic, and phosphoric acid anodizing, whereas poorly ordered porous alumina is fabricated via chromic acid anodizing [22,23]. Cyclic oxocarbonic acids such as squaric [24], croconic, and rhodizonic[25] acid were very recently determined to be suitable organic electrolytes for fabricating porous alumina, although the details of the growth behavior are still unknown. Carboxylic acids can also be employed ...