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Nanostructured Anodic Oxides: Fabrication, Characterization and Application

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 30402

Special Issue Editor


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Guest Editor
1. Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA
2. Department of Advanced Materials & Technologies, Military University of Technology, Kaliskiego 2 Str, 00908 Warsaw, Poland
Interests: anodization; nanostructured anodic oxides; anodic aluminum oxide; anodic oxides on copper; nanofabrication; CO2 reduction reaction
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Special Issue Information

Dear Colleagues,

The anodization of metals, especially aluminum, has been widely utilized in corrosion engineering during the last few decades. Anodic alumina provides insulation, compact layering, and corrosion protection. Since 1995, when Masuda and Fukuda from Tokyo Metropolitan University published their groundbreaking paper reporting two-step anodization of aluminum, anodization has become one of the most researched techniques in nanotechnology. Two-step, self-organized anodizing has allowed for the formation of highly ordered, uniform nanopores with morphologies that can be tuned by operating conditions. Such formed material serves as a template for the nanofabrication of nanowires, nanotubes, and nanodots made of a variety of materials.

Today, other metals and alloys, such as titanium, zinc, zirconium, copper, iron, and cobalt, are anodized. Moreover, these nanostructured oxides contribute to emerging applications, such as CO2 reduction, solar cells, sensing, and implant materials.

The forthcoming Special Issue will focus on recent advancements in the field of nanostructured anodic oxides. Topics include, but are not limited to:

  • Fundamental and mechanistic issues of anodizing;
  • Characterization of chemical composition, geometry, and arrangement of anodically grown oxides;
  • Study of the influence of operating conditions of anodizing on oxide growth;
  • New experimental conditions for anodizing;
  • Anodization of new metals and alloys;
  • Study of the properties of anodically grown oxides;
  • Applications of anodically grown oxides.

We invite our colleagues to contribute full papers, reviews, or communications to this Special Issue.

Dr. Wojciech J. Stepniowski
Guest Editor

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Keywords

  • anodization
  • self-organization
  • nanotechnology
  • nanopores
  • nanowires
  • nanotubes
  • passivation
  • nanofabrication
  • corrosion
  • electrochemistry

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Published Papers (8 papers)

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Research

Jump to: Review

15 pages, 7415 KiB  
Article
Growth of Anodic Layers on 304L Stainless Steel Using Fluoride Free Electrolytes and Their Electrochemical Behavior in Chloride Solution
by Laura Patricia Domínguez-Jaimes, María A. Arenas, Ana Conde, Beatriz Escobar-Morales, Anabel Álvarez-Méndez and Juan Manuel Hernández-López
Materials 2022, 15(5), 1892; https://doi.org/10.3390/ma15051892 - 3 Mar 2022
Cited by 7 | Viewed by 2525
Abstract
Anodic layers have been grown on 304L stainless steel (304L SS) using two kinds of fluoride-free organic electrolytes. The replacement of NH4F for NaAlO2 or Na2SiO3 in the glycerol solution and the influence of the H2 [...] Read more.
Anodic layers have been grown on 304L stainless steel (304L SS) using two kinds of fluoride-free organic electrolytes. The replacement of NH4F for NaAlO2 or Na2SiO3 in the glycerol solution and the influence of the H2O concentration have been examined. The obtained anodic layers were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and potentiodynamic polarization tests. Here, it was found that, although the anodic layers fabricated within the NaAlO2-electrolyte and high H2O concentrations presented limited adherence to the substrate, the anodizing in the Na2SiO3-electrolyte and low H2O concentrations allowed the growth oxide layers, and even a type of ordered morphology was observed. Furthermore, the electrochemical tests in chloride solution determined low chemical stability and active behavior of oxide layers grown in NaAlO2-electrolyte. In contrast, the corrosion resistance was improved approximately one order of magnitude compared to the non-anodized 304L SS substrate for the anodizing treatment in glycerol, 0.05 M Na2SiO3, and 1.7 vol% H2O at 20 mA/cm2 for 6 min. Thus, this anodizing condition offers insight into the sustainable growth of oxide layers with potential anti-corrosion properties. Full article
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19 pages, 4407 KiB  
Article
A Strategy towards Light-Absorbing Coatings Based on Optically Black Nanoporous Alumina with Tailored Disorder
by Mikhail Pashchanka and Gennady Cherkashinin
Materials 2021, 14(19), 5827; https://doi.org/10.3390/ma14195827 - 5 Oct 2021
Cited by 6 | Viewed by 2041
Abstract
This work provides a conceptually new way of thinking about the light-absorbing mechanism in additive-free black porous anodic alumina (black PAA, or b-PAA) layers obtained via “burning” anodizing regime. The new insight into the controllable photonic effects in PAA allows the implementation of [...] Read more.
This work provides a conceptually new way of thinking about the light-absorbing mechanism in additive-free black porous anodic alumina (black PAA, or b-PAA) layers obtained via “burning” anodizing regime. The new insight into the controllable photonic effects in PAA allows the implementation of the optical blackening method based on the deliberate randomization of the initially well-ordered nanopore arrangement. The proposed black coloration mechanism rests solely on the destructive interference of light after its multiple scattering. Similar effects have been earlier considered for some natural or artificially created biomimetic structures (e.g., the so-called “moth eye effect”, or the coloration mechanism in the Neurothemis tullia dragonfly wings). Comprehensive analysis confirmed that the chemical composition of b-PAA has only a minor influence on the color changes and the optical density increase, and that the light-absorbing properties most likely result from the structural effects. The new functional 2D materials exhibit strong adhesion to aluminum surface, are cost-effective and suitable for application under harsh thermal or UV-light conditions. They are potentially useful for manufacturing of optical devices or heat-resistant coatings in aerospace technologies, as well as solid supports for biological filtration and fluorescence imaging. Full article
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13 pages, 4703 KiB  
Article
Fabrication, Characterization and Photocatalytic Activity of Copper Oxide Nanowires Formed by Anodization of Copper Foams
by Alaa M. Abd-Elnaiem, Moustafa A. Abdel-Rahim, Atta Y. Abdel-Latief, Ahmed Abdel-Rahim Mohamed, Kristina Mojsilović and Wojciech Jerzy Stępniowski
Materials 2021, 14(17), 5030; https://doi.org/10.3390/ma14175030 - 2 Sep 2021
Cited by 19 | Viewed by 3309
Abstract
In recent paper anodization of copper foams in 0.1 M K2CO3 is reported. Anodization was performed in the voltage range of 5–25 V and in all the cases oxides with a developed surface area were obtained. However, anodizing only at [...] Read more.
In recent paper anodization of copper foams in 0.1 M K2CO3 is reported. Anodization was performed in the voltage range of 5–25 V and in all the cases oxides with a developed surface area were obtained. However, anodizing only at 20 and 25 V resulted in the formation of nanostruc-tures. In all the cases, the products of anodizing consisted of crystalline phases like cuprite (Cu2O), tenorite (CuO), parameconite (Cu4O3) as well as spertiniite (Cu(OH)2). Copper foams after ano-dizing were applied as catalysts in the photocatalytic decolorization of a model organic compound such as methylene blue. The highest photocatalytic activity was observed for samples anodized at 25 V and closely followed by samples anodized at 5 V. The anodized copper foams proved to be a useful material in enhancing the photocatalytic efficiency of organic dye decomposition. Full article
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17 pages, 7376 KiB  
Article
TiO2 Nanotubes with Pt and Pd Nanoparticles as Catalysts for Electro-Oxidation of Formic Acid
by Marcin Pisarek, Piotr Kędzierzawski, Mariusz Andrzejczuk, Marcin Hołdyński, Anna Mikołajczuk-Zychora, Andrzej Borodziński and Maria Janik-Czachor
Materials 2020, 13(5), 1195; https://doi.org/10.3390/ma13051195 - 6 Mar 2020
Cited by 22 | Viewed by 4296
Abstract
In the present work, the magnetron sputtering technique was used to prepare new catalysts of formic acid electrooxidation based on TiO2 nanotubes decorated with Pt (platinum), Pd (palladium) or Pd + Pt nanoparticles. TiO2 nanotubes (TiO2 NTs) with strictly defined [...] Read more.
In the present work, the magnetron sputtering technique was used to prepare new catalysts of formic acid electrooxidation based on TiO2 nanotubes decorated with Pt (platinum), Pd (palladium) or Pd + Pt nanoparticles. TiO2 nanotubes (TiO2 NTs) with strictly defined geometry were produced by anodization of Ti foil and Ti mesh in a mixture of glycerol and water with ammonium fluoride electrolyte. The above mentioned catalytically active metal nanoparticles (NPs) were located mainly on the top of the TiO2 NTs, forming ‘rings’ and agglomerates. A part of metal nanoparticles decorated also TiO2 NTs walls, thus providing sufficient electronic conductivity for electron transportation between the metal nanoparticle rings and Ti current collector. The electrocatalytic activity of the TiO2 NTs/Ti foil, decorated by Pt, Pd and/or Pd + Pt NPs was investigated by cyclic voltammetry (CV) and new Pd/TiO2 NTs/Ti mesh catalyst was additionally tested in a direct formic acid fuel cell (DFAFC). The results so obtained were compared with commercial catalyst—Pd/Vulcan. CV tests have shown for carbon supported catalysts, that the activity of TiO2 NTs decorated with Pd was considerably higher than that one decorated with Pt. Moreover, for TiO2 NTs supported Pd catalyst specific activity (per mg of metal) was higher than that for well dispersed carbon supported commercial catalyst. The tests at DFAFC have revealed also that the maximum of specific power for 0.2 Pd/TiO2 catalyst was 70% higher than that of the commercial one, Pd/Vulcan. Morphological features, and/or peculiarities, as well as surface composition of the resulting catalysts have been studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and chemical surface analytical methods (X-ray photoelectron spectroscopy—XPS; Auger electron spectroscopy—AES). Full article
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12 pages, 4087 KiB  
Article
A Superhydrophilic Aluminum Surface with Fast Water Evaporation Based on Anodic Alumina Bundle Structures via Anodizing in Pyrophosphoric Acid
by Daiki Nakajima, Tatsuya Kikuchi, Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda, Ryosuke O. Suzuki and Shungo Natsui
Materials 2019, 12(21), 3497; https://doi.org/10.3390/ma12213497 - 25 Oct 2019
Cited by 28 | Viewed by 5188
Abstract
A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina [...] Read more.
A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina nanofibers, and completely bent nanofibers. During the water contact angle measurements at 1 s after the water droplet was placed on the anodized surface, the contact angle rapidly decreased to less than 10°, and superhydrophilic behavior with the lowest contact angle measuring 2.0° was exhibited on the surface covered with the pyramidal bundle structures. As the measurement time of the contact angle decreased to 200–33 ms after the water placement, although the contact angle slightly increased in the initial stage due to the formation of porous alumina, at 33 ms after the water placement, the contact angle was 9.8°, indicating that superhydrophilicity with fast water evaporation was successfully obtained on the surface covered with the pyramidal bundle structures. We found that the shape of the pyramidal bundle structures was maintained in water without separation by in situ high-speed atomic force microscopy measurements. Full article
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18 pages, 8014 KiB  
Article
Cubic Silver Nanoparticles Fixed on TiO2 Nanotubes as Simple and Efficient Substrates for Surface Enhanced Raman Scattering
by Robert Ambroziak, Marcin Hołdyński, Tomasz Płociński, Marcin Pisarek and Andrzej Kudelski
Materials 2019, 12(20), 3373; https://doi.org/10.3390/ma12203373 - 16 Oct 2019
Cited by 28 | Viewed by 4788
Abstract
In this work we show that ordered freestanding titanium oxide nanotubes (TiO2 NT) may be used as substrates for the simple and efficient immobilization of anisotropic plasmonic nanoparticles. This is important because anisotropic plasmonic nanostructures usually give greater spectral enhancement than spherical [...] Read more.
In this work we show that ordered freestanding titanium oxide nanotubes (TiO2 NT) may be used as substrates for the simple and efficient immobilization of anisotropic plasmonic nanoparticles. This is important because anisotropic plasmonic nanostructures usually give greater spectral enhancement than spherical nanoparticles. The size of the pores in a layer of titanium oxide nanotubes can be easily fitted to the size of many silver plasmonic nanoparticles highly active in SERS (surface-enhanced Raman scattering) spectroscopy (for example, silver nanocubes with an edge length of ca. 45 nm), and hence, the plasmonic nanoparticles deposited can be strongly anchored in such a titanium oxide substrate. The tubular morphology of the TiO2 substrate used allows a specific arrangement of the silver plasmonic nanoparticles that may create many so-called SERS hot spots. The SERS activity of a layer of cubic Ag nanoparticles (AgCNPs) deposited on a tubular TiO2 substrate (AgCNPs@TiO2 NT) is about eight times higher than that of the standard electrochemically nanostructured surface of a silver electrode (produced by oxidation reduction cycling). Furthermore, a super hydrophilic character of the TiO2 nanotubes surface allows for a uniform distribution of AgCNPs, which are deposited from an aqueous suspension. The new AgCNPs@TiO2 NT hybrid layer ensures a good reproducibility of SERS measurements and exhibits a higher temporal stability of the achievable total SERS enhancement factor—one that is far better than standard SERS silver substrates. To characterize the morphology and chemical composition of such evidently improved SERS platforms thus received, we applied microscopic techniques (SEM, and scanning transmission electron microscopy (STEM)) and surface analytical techniques (Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS)). Full article
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8 pages, 2057 KiB  
Article
Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl3 Intermetallic Alloy
by Paulina Chilimoniuk, Marta Michalska-Domańska and Tomasz Czujko
Materials 2019, 12(14), 2299; https://doi.org/10.3390/ma12142299 - 18 Jul 2019
Cited by 6 | Viewed by 2876
Abstract
Nanostructured anodic oxide layers on an FeAl3 intermetallic alloy were prepared by two-step anodization in 20 wt% H2SO4 at 0 °C. The voltage range was 10.0–22.5 V with a step of 2.5 V. The structural and morphological characterizations of [...] Read more.
Nanostructured anodic oxide layers on an FeAl3 intermetallic alloy were prepared by two-step anodization in 20 wt% H2SO4 at 0 °C. The voltage range was 10.0–22.5 V with a step of 2.5 V. The structural and morphological characterizations of the received anodic oxide layers were performed by field emission scanning electron microscopy (FE-SEM). Therefore, the formed anodic oxide was found to be highly porous with a high surface area, as indicated by the FE-SEM studies. It has been shown that the morphology of fabricated nanoporous oxide layers is strongly affected by the anodization potential. The oxide growth rate first increased slowly (from 0.010 μm/s for 10 V to 0.02 μm/s for 15 V) and then very rapidly (from 0.04 μm/s for 17.5 V up to 0.13 μm/s for 22.5 V). The same trend was observed for the change in the oxide thickness. Moreover, for all investigated anodizing voltages, the structural features of the anodic oxide layers, such as the pore diameter and interpore distance, increased with increasing anodizing potential. The obtained anodic oxide layer was identified as a crystalline FeAl2O4, Fe2O3 and Al2O3 oxide mixture. Full article
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Review

Jump to: Research

38 pages, 5016 KiB  
Review
The Use of Anodic Oxides in Practical and Sustainable Devices for Energy Conversion and Storage
by Janaina Soares Santos, Patrícia dos Santos Araújo, Yasmin Bastos Pissolitto, Paula Prenholatto Lopes, Anna Paulla Simon, Mariana de Souza Sikora and Francisco Trivinho-Strixino
Materials 2021, 14(2), 383; https://doi.org/10.3390/ma14020383 - 14 Jan 2021
Cited by 21 | Viewed by 4415
Abstract
This review addresses the main contributions of anodic oxide films synthesized and designed to overcome the current limitations of practical applications in energy conversion and storage devices. We present some strategies adopted to improve the efficiency, stability, and overall performance of these sustainable [...] Read more.
This review addresses the main contributions of anodic oxide films synthesized and designed to overcome the current limitations of practical applications in energy conversion and storage devices. We present some strategies adopted to improve the efficiency, stability, and overall performance of these sustainable technologies operating via photo, photoelectrochemical, and electrochemical processes. The facile and scalable synthesis with strict control of the properties combined with the low-cost, high surface area, chemical stability, and unidirectional orientation of these nanostructures make the anodized oxides attractive for these applications. Assuming different functionalities, TiO2-NT is the widely explored anodic oxide in dye-sensitized solar cells, PEC water-splitting systems, fuel cells, supercapacitors, and batteries. However, other nanostructured anodic films based on WO3, CuxO, ZnO, NiO, SnO, Fe2O3, ZrO2, Nb2O5, and Ta2O5 are also explored and act as the respective active layers in several devices. The use of AAO as a structural material to guide the synthesis is also reported. Although in the development stage, the proof-of-concept of these devices demonstrates the feasibility of using the anodic oxide as a component and opens up new perspectives for the industrial and commercial utilization of these technologies. Full article
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