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Advances in Electrochemical Fabrication of Nanoporous Materials
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Advances in Electrochemical Fabrication of Nanoporous Materials

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 19035

Special Issue Editor

Dr. Leszek Zaraska

E-Mail Website
Guest Editor
Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
Interests: electrochemistry; electrochemical synthesis of nanostructured materials; anodic oxidation; nanostructured semiconductors; photoelectrochemical water splitting
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nanoporous materials have received great scientific and technological interest owing to their excellent properties, which lead to a great variety of possible applications, including but not limited to energy conversion and storage, catalysis, separation technologies, sensors, optical, magnetic, and electronic devices. Therefore, the efforts of many groups are focused on the development of new, easily implementable, and relatively cheap methods of fabrication of such materials. Among the many strategies that have been already proposed, electrochemical processes, such as controlled electrochemical oxidation (anodization), are especially interesting and promising. Simplicity, low cost, and easily accessible equipment seem to be the most important advantages of these methods.

A great variety of nanoporous materials, including metal oxides (e.g., Al2O3, TiO2, WO3, ZrO2, SnO2, ZnO), semiconductors (e.g., Si, InP, GaP), or metals (e.g., Au) have been successfully obtained via this method. What is more, the geometrical features of porous materials can be controlled, to some extent, by adjustment of anodizing conditions that opens many perspectives for fabrication of nanoporous structures with a precisely defined morphology and properties, dedicated to particular applications. During recent years, tremendous progress in the development of new electrochemical methods for fabrication of nanoporous materials has been observed.

Therefore, in this Special Issue of Nanomaterials, we expect both regular research papers and reviews on all aspects related to electrochemical methods that can be used for the synthesis of nanoporous materials. Articles describing new strategies of electrochemical synthesis, as well as characterization and possible applications of electrochemically formed nanoporous materials, are especially welcome.

Dr. Leszek Zaraska
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanoporous materials
  • Electrochemical methods
  • Anodization
  • Electrodeposition

Published Papers (7 papers)

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Research

13 pages, 14513 KiB  
Article
Improvement of Corrosion Resistance of Stainless Steel Welded Joint Using a Nanostructured Oxide Layer
by Jun Heo, Sang Yoon Lee, Jaewoo Lee, Akram Alfantazi and Sung Oh Cho
Nanomaterials 2021, 11(4), 838; https://doi.org/10.3390/nano11040838 - 25 Mar 2021
Cited by 4 | Viewed by 2073
Abstract
In this study, we fabricated a nanoporous oxide layer by anodization to improve corrosion resistance of type 304 stainless steel (SS) gas tungsten arc weld (GTAW). Subsequent heat treatment was performed to eliminate any existing fluorine in the nanoporous oxide layer. Uniform structures [...] Read more.
In this study, we fabricated a nanoporous oxide layer by anodization to improve corrosion resistance of type 304 stainless steel (SS) gas tungsten arc weld (GTAW). Subsequent heat treatment was performed to eliminate any existing fluorine in the nanoporous oxide layer. Uniform structures and compositions were analyzed with field emission scanning electron microscope (FESEM) and X-ray diffractometer (XRD) measurements. The corrosion resistance of the treated SS was evaluated by applying a potentiodynamic polarization (PDP) technique and electrochemical impedance spectroscopy (EIS). Surface morphologies of welded SS with and without treatment were examined to compare their corrosion behaviors. All results indicate that corrosion resistance was enhanced, making the treatment process highly promising. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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17 pages, 7581 KiB  
Article
Preparation and Characterization of Electrospun Fluoro-Containing Poly(imide-benzoxazole) Nano-Fibrous Membranes with Low Dielectric Constants and High Thermal Stability
by Meng-Ge Huangfu, Deng-Xiong Shen, Xin-Xin Zhi, Yan Zhang, Yan-Jiang Jia, Yuan-Cheng An, Xin-Ying Wei and Jin-Gang Liu
Nanomaterials 2021, 11(2), 537; https://doi.org/10.3390/nano11020537 - 19 Feb 2021
Cited by 3 | Viewed by 2876
Abstract
The rapid development of advanced high-frequency mobile communication techniques has advanced urgent requirements for polymer materials with high-temperature resistance and good dielectric properties, including low dielectric constants (low-Dk) and low dielectric dissipation factors (low-Df). The relatively poor [...] Read more.
The rapid development of advanced high-frequency mobile communication techniques has advanced urgent requirements for polymer materials with high-temperature resistance and good dielectric properties, including low dielectric constants (low-Dk) and low dielectric dissipation factors (low-Df). The relatively poor dielectric properties of common polymer candidates, such as standard polyimides (PIs) greatly limited their application in high-frequency areas. In the current work, benzoxazole units were successfully incorporated into the molecular structures of the fluoro-containing PIs to afford the poly(imide-benzoxazole) (PIBO) nano-fibrous membranes (NFMs) via electrospinning fabrication. First, the PI NFMs were prepared by the electrospinning procedure from organo-soluble PI resins derived from 2,2′-bis(3,4-dicarboxy-phenyl)hexafluoropropane dianhydride (6FDA) and aromatic diamines containing ortho-hydroxy-substituted benzamide units, including 2,2-bis[3-(4-aminobenzamide)-4-hydroxylphenyl]hexafluoropropane (p6FAHP) and 2,2-bis[3-(3-aminobenzamide)-4-hydroxyphenyl]hexafluoropropane (m6FAHP). Then, the PI NFMs were thermally dehydrated at 350 °C in nitrogen to afford the PIBO NFMs. The average fiber diameters (dav) for the PIBO NFMs were 1225 nm for PIBO-1 derived from PI-1 (6FDA-p6FAHP) precursor and 816 nm for PIBO-2 derived from PI-2 (6FDA-m6FAHP). The derived PIBO NFMs showed good thermal stability with the glass transition temperatures (Tgs) over 310 °C and the 5% weight loss temperatures (T5%) higher than 500 °C in nitrogen. The PIBO NFMs showed low dielectric features with the Dk value of 1.64 for PIBO-1 and 1.82 for PIBO-2 at the frequency of 1 MHz, respectively. The Df values were in the range of 0.010~0.018 for the PIBO NFMs. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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14 pages, 3682 KiB  
Article
Electrochemical Oxidation of Ti15Mo Alloy—The Impact of Anodization Parameters on Surface Morphology of Nanostructured Oxide Layers
by Magdalena Jarosz, Leszek Zaraska, Marcin Kozieł, Wojciech Simka and Grzegorz D. Sulka
Nanomaterials 2021, 11(1), 68; https://doi.org/10.3390/nano11010068 - 30 Dec 2020
Cited by 5 | Viewed by 2108
Abstract
It is well-known that the structure and composition of the material plays an important role in the processes occurring at the surface. In this paper, a surface morphology of nanostructured oxide layers electrochemically grown on Ti15Mo, tuned by applying different anodization parameters, was [...] Read more.
It is well-known that the structure and composition of the material plays an important role in the processes occurring at the surface. In this paper, a surface morphology of nanostructured oxide layers electrochemically grown on Ti15Mo, tuned by applying different anodization parameters, was investigated in detail. The one-step anodization of Ti15Mo alloy was performed at room temperature in an ethylene glycol-based electrolyte containing 0.11 M NH4F and 1.11 M H2O. Different anodization times (ranging from 5 to 60 min) and applied potentials (40–100 V) were tested, and the surface morphology, elemental content, and crystalline structure were monitored by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffractometry (XRD), respectively. The results showed that contrary to the multistep anodization of titanium foil, the surface morphology of anodic oxide obtained via the one-step process contains the nanoporous outer layer covering the nanotubular structure. What is more, the pore diameter (Dp) and interpore distance (Dint) of such layers exhibit different trends than those observed for anodization of pure titanium. In particular, at a certain potential range, a decrease in both Dp and Dint with increasing potential was observed. However, independently on the used anodization conditions, the elemental content of oxide layers remained similar, showing the amount of molybdenum at c.a. 15 wt.%. Finally, the amorphous nature of as-anodized layers was confirmed, and their optical band-gap was determined from the diffuse reflectance UV–Vis spectra. It was found that Eg is tunable to some extent by changing the anodizing potential. However, further thermal treatment in air at 400 °C resulted in the anatase phase formation that was accompanied by a significant Eg reduction. Therefore, we believe that the presented results will greatly contribute to the understanding of anodic formation of nanostructured functional oxide layers with tunable properties that can be applied in various fields. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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12 pages, 5525 KiB  
Article
Formation of Free-Standing Inverse Opals with Gradient Pores
by Pei-Sung Hung, Chen-Hong Liao, Bo-Han Huang, Wei-An Chung, Shou-Yi Chang and Pu-Wei Wu
Nanomaterials 2020, 10(10), 1923; https://doi.org/10.3390/nano10101923 - 26 Sep 2020
Cited by 5 | Viewed by 1889
Abstract
We demonstrate the fabrication of free-standing inverse opals with gradient pores via a combination of electrophoresis and electroplating techniques. Our processing scheme starts with the preparation of multilayer colloidal crystals by conducting sequential electrophoresis with polystyrene (PS) microspheres in different sizes (300, 600, [...] Read more.
We demonstrate the fabrication of free-standing inverse opals with gradient pores via a combination of electrophoresis and electroplating techniques. Our processing scheme starts with the preparation of multilayer colloidal crystals by conducting sequential electrophoresis with polystyrene (PS) microspheres in different sizes (300, 600, and 1000 nm). The critical factors affecting the stacking of individual colloidal crystals are discussed and relevant electrophoresis parameters are identified so the larger PS microspheres are assembled successively atop of smaller ones in an orderly manner. In total, we construct multilayer colloidal crystals with vertical stacking of microspheres in 300/600, 300/1000, and 300/600/1000 nm sequences. The inverse opals with gradient pores are produced by galvanostatic plating of Ni, followed by the selective removal of colloidal template. Images from scanning electron microscopy exhibit ideal multilayer close-packed structures with well-defined boundaries among different layers. Results from porometer analysis reveal the size of bottlenecks consistent with those of interconnected pore channels from inverse opals of smallest PS microspheres. Mechanical properties determined by nanoindentation tests indicate significant improvements for multilayer inverse opals as compared to those of conventional single-layer inverse opals. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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15 pages, 6555 KiB  
Article
The In-Depth Studies of Pulsed UV Laser-Modified TiO2 Nanotubes: The Influence of Geometry, Crystallinity, and Processing Parameters
by Łukasz Haryński, Katarzyna Grochowska, Piotr Kupracz, Jakub Karczewski, Emerson Coy and Katarzyna Siuzdak
Nanomaterials 2020, 10(3), 430; https://doi.org/10.3390/nano10030430 - 28 Feb 2020
Cited by 14 | Viewed by 2642
Abstract
The laser processing of the titania nanotubes has been investigated in terms of morphology, structure, and optical properties of the obtained material. The length of the nanotubes and crystallinity, as well as the atmosphere of the laser treatment, were taken into account. The [...] Read more.
The laser processing of the titania nanotubes has been investigated in terms of morphology, structure, and optical properties of the obtained material. The length of the nanotubes and crystallinity, as well as the atmosphere of the laser treatment, were taken into account. The degree of changes of the initial geometry of nanotubes were checked by means of scanning electron microscopy, which visualizes both the surface and the cross-section. The phase conversion from the amorphous to anatase has been achieved for laser-treated amorphous material, whereas modification of calcined one led to distortion within the crystal structure. This result is confirmed both by Raman and grazing incident XRD measurements. The latter studies provided an in-depth analysis of the crystalline arrangement and allowed also for determining the propagation of laser modification. The narrowing of the optical bandgap for laser-treated samples has been observed. Laser treatment of TiO2 nanotubes can lead to the preparation of the material of desired structural and optical parameters. The usage of the motorized table during processing enables induction of changes in the precisely selected area of the sample within a very short time. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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12 pages, 2546 KiB  
Article
Hierarchical Nanoporous Sn/SnOx Systems Obtained by Anodic Oxidation of Electrochemically Deposited Sn Nanofoams
by Magdalena Gurgul, Anton S. Lytvynenko, Magdalena Jarosz, Karolina Gawlak, Grzegorz D. Sulka and Leszek Zaraska
Nanomaterials 2020, 10(3), 410; https://doi.org/10.3390/nano10030410 - 26 Feb 2020
Cited by 5 | Viewed by 2946
Abstract
A simple two-step electrochemical method for the fabrication of a new type of hierarchical Sn/SnOx micro/nanostructures is proposed for the very first time. Firstly, porous metallic Sn foams are grown on Sn foil via hydrogen bubble-assisted electrodeposition from an acidulated tin chloride [...] Read more.
A simple two-step electrochemical method for the fabrication of a new type of hierarchical Sn/SnOx micro/nanostructures is proposed for the very first time. Firstly, porous metallic Sn foams are grown on Sn foil via hydrogen bubble-assisted electrodeposition from an acidulated tin chloride electrolyte. As-obtained metallic foams consist of randomly distributed dendrites grown uniformly on the entire metal surface. The estimated value of pore diameter near the surface is ~35 µm, while voids with a diameter of ~15 µm appear in a deeper part of the deposit. Secondly, a layer of amorphous nanoporous tin oxide (with a pore diameter of ~60 nm) is generated on the metal surface by its anodic oxidation in an alkaline electrolyte (1 M NaOH) at the potential of 4 V for various durations. It is confirmed that if only optimal conditions are applied, the dendritic morphology of the metal foam does not change significantly, and an open-porous structure is still preserved after anodization. Such kinds of hierarchical nanoporous Sn/SnOx systems are superhydrophilic, contrary to those obtained by thermal oxidation of metal foams which are hydrophobic. Finally, the photoelectrochemical activity of the nanostructured metal/metal oxide electrodes is also presented. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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13 pages, 4395 KiB  
Article
Performance-Enhanced 365 nm UV LEDs with Electrochemically Etched Nanoporous AlGaN Distributed Bragg Reflectors
by Xingdong Lu, Jing Li, Kang Su, Chang Ge, Zhicong Li, Teng Zhan, Guohong Wang and Jinmin Li
Nanomaterials 2019, 9(6), 862; https://doi.org/10.3390/nano9060862 - 06 Jun 2019
Cited by 12 | Viewed by 3722
Abstract
A 365-nm UV LED was fabricated based on embedded nanoporous AlGaN distributed Bragg reflectors (DBR) by electrochemical etching. The porous DBR had a reflectance of 93.5% at the central wavelength of 365 nm; this is the highest value of porous AlGaN DBRs below [...] Read more.
A 365-nm UV LED was fabricated based on embedded nanoporous AlGaN distributed Bragg reflectors (DBR) by electrochemical etching. The porous DBR had a reflectance of 93.5% at the central wavelength of 365 nm; this is the highest value of porous AlGaN DBRs below 370 nm which has been reported so far. An innovative two-step etching method with a SiO2 sidewall protection layer (SPL) was proposed to protect the n-AlGaN layer and active region of UV LED from being etched by the electrolyte. The DBR-LED with SPL showed 54.3% improvement of maximal external quantum efficiency (EQE) and 65.7% enhancement of optical power at 100 mA without any degeneration in electrical properties, compared with the un-etched standard LED sample. This work has paved the way for the application of electrically-pumped UV LEDs and VCSELs based on nanoporous AlGaN DBRs. Full article
(This article belongs to the Special Issue Advances in Electrochemical Fabrication of Nanoporous Materials)
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