Special Issue "Electrochemically Engineering of Nanoporous Materials"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 March 2018)

Special Issue Editor

Guest Editor
Dr. Abel Santos

1. School of Chemical Engineering, The University of Adelaide, Engineering North Building, Adelaide, SA 5005, Australia
2. The Institute for Photonics & Advanced Sensing (IPAS), The University of Adelaide
3. ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide
Website | E-Mail
Interests: structural engineering and synthesis of nanoporous materials by electrochemical etching; nanophotonics and photonics; optical sensing and biosensing; smart drug delivery from nanocarriers and surface coatings for biomedical applications; microfluidic lab-on-a-chip systems for all-in-one sensing applications; photo-catalysis

Special Issue Information

Dear Colleagues, 

Electrochemical engineering of nanoporous materials is a cost-effective and facile synthesis approach that enables the production of a range of nanoscale materials with controllable dimensions and properties. Recent decades have witnessed extensive research activity into the advanced engineering of nanoporous materials, from fundamental studies to applied science. These nanomaterials offer a set of unique and exclusive advantages for a wealth of applications, including catalysis, energy storage and harvesting, electronics, photonics, sensing, templates, and membranes.

This Special Issue is dedicated to recent research advances in electrochemical engineering of nanoporous materials and their application across several disciplines and research fields. The broad and interdisciplinary applicability of these nanomaterials will be of profound and immediate interest for a broad audience, ranging from physicists, chemists, engineers, materials scientists, bioengineers, and nanomedicine experts.

Dr. Abel Santos
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 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

  • Electrochemical Etching
  • Anodization
  • Fabrication of nanoporous materials
  • Nanoporous materials for sensing and biosensing
  • Nanoporous materials for biomedical applications
  • Nanoporous materials for energy storage and harvesting
  • Nanoporous materials for catalysis
  • Nanoporous materials for membrane science
  • Nanoporous materials for electronics
  • Nanoporous materials for optics and photonics

Published Papers (10 papers)

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Research

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Open AccessArticle Single-Walled Carbon Nanotube (SWCNT) Loaded Porous Reticulated Vitreous Carbon (RVC) Electrodes Used in a Capacitive Deionization (CDI) Cell for Effective Desalination
Nanomaterials 2018, 8(7), 527; https://doi.org/10.3390/nano8070527
Received: 7 March 2018 / Revised: 6 June 2018 / Accepted: 3 July 2018 / Published: 13 July 2018
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Abstract
Acid-functionalized single-walled carbon nanotube (a-SWCNT)-coated reticulated vitreous carbon (RVC) composite electrodes have been prepared and the use of these electrodes in capacitive deionization (CDI) cells for water desalination has been the focus of this study. The performance of these electrodes was tested based
[...] Read more.
Acid-functionalized single-walled carbon nanotube (a-SWCNT)-coated reticulated vitreous carbon (RVC) composite electrodes have been prepared and the use of these electrodes in capacitive deionization (CDI) cells for water desalination has been the focus of this study. The performance of these electrodes was tested based on the applied voltage, flow rate, bias potential and a-SWCNT loadings, and then evaluated by electrosorption dynamics. The effect of the feed stream directly through the electrodes, between the electrodes, and the distance between the electrodes in the CDI system on the performance of the electrodes has been investigated. The interaction of ions with the electrodes was tested through Langmuir and Freundlich isotherm models. A new CDI cell was developed, which shows an increase of 23.96% in electrosorption capacity compared to the basic CDI cells. Moreover, a comparison of our results with the published results reveals that RVC/a-SWCNT electrodes produce 16 times more pure water compared to the ones produced using only CNT-based electrodes. Finally, it can be inferred that RVC/a-SWCNT composite electrodes in newly-developed CDI cells can be effectively used in desalination technology for water purification. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Titanium Dioxide Nanotubes as Model Systems for Electrosorption Studies
Nanomaterials 2018, 8(6), 404; https://doi.org/10.3390/nano8060404
Received: 2 April 2018 / Revised: 20 May 2018 / Accepted: 23 May 2018 / Published: 5 June 2018
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Abstract
Highly ordered titanium dioxide nanotubes (TiO2 NTs) were fabricated through anodization and tested for their applicability as model electrodes in electrosorption studies. The crystalline structure of the TiO2 NTs was changed without modifying the nanostructure of the surface. Electrosorption capacity, charging
[...] Read more.
Highly ordered titanium dioxide nanotubes (TiO2 NTs) were fabricated through anodization and tested for their applicability as model electrodes in electrosorption studies. The crystalline structure of the TiO2 NTs was changed without modifying the nanostructure of the surface. Electrosorption capacity, charging rate, and electrochemical active surface area of TiO2 NTs with two different crystalline structures, anatase and amorphous, were investigated via chronoamperometry, cyclic voltammetry, and electrochemical impedance spectroscopy. The highest electrosorption capacities and charging rates were obtained for the anatase TiO2 NTs, largely because anatase TiO2 has a reported higher electrical conductivity and a crystalline structure that can potentially accommodate small ions within. Both electrosorption capacity and charging rate for the ions studied in this work follow the order of Cs+ > Na+ > Li+, regardless of the crystalline structure of the TiO2 NTs. This order reflects the increasing size of the hydrated ion radii of these monovalent ions. Additionally, larger effective electrochemical active surface areas are required for larger ions and lower conductivities. These findings point towards the fact that smaller hydrated-ions experience less steric hindrance and a larger comparative electrostatic force, enabling them to be more effectively electrosorbed. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Electrodes Based on Carbon Aerogels Partially Graphitized by Doping with Transition Metals for Oxygen Reduction Reaction
Nanomaterials 2018, 8(4), 266; https://doi.org/10.3390/nano8040266
Received: 18 April 2018 / Revised: 18 April 2018 / Accepted: 20 April 2018 / Published: 23 April 2018
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Abstract
A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of
[...] Read more.
A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of the metal loading. All aerogels have been characterized to analyze their textural properties, surface chemistry and crystal structures. These metal-doped aerogels have a very well-developed porosity, making their mesoporosity remarkable. Ni-doped aerogels are the ones with the largest surface area and the smallest graphitization. They also present larger mesopore volumes than Co- and Fe-doped aerogels. These materials are tested as electro-catalysts for the oxygen reduction reaction. Results show a clear and strong influence of the carbonaceous structure on the whole electro-catalytic behavior of the aerogels. Regarding the type of metal doping, aerogel doped with Co is the most active one, followed by Ni- and Fe-doped aerogels, respectively. As the Ni content is larger, the kinetic current densities increase. Comparatively, among the different doping metals, the results obtained with Ni are especially remarkable. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Tailoring of Perpendicular Magnetic Anisotropy in Dy13Fe87 Thin Films with Hexagonal Antidot Lattice Nanostructure
Nanomaterials 2018, 8(4), 227; https://doi.org/10.3390/nano8040227
Received: 10 March 2018 / Revised: 31 March 2018 / Accepted: 5 April 2018 / Published: 8 April 2018
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Abstract
In this article, the magnetic properties of hexagonally ordered antidot arrays made of Dy13Fe87 alloy are studied and compared with corresponding ones of continuous thin films with the same compositions and thicknesses, varying between 20 nm and 50 nm. Both
[...] Read more.
In this article, the magnetic properties of hexagonally ordered antidot arrays made of Dy13Fe87 alloy are studied and compared with corresponding ones of continuous thin films with the same compositions and thicknesses, varying between 20 nm and 50 nm. Both samples, the continuous thin films and antidot arrays, were prepared by high vacuum e-beam evaporation of the alloy on the top-surface of glass and hexagonally self-ordered nanoporous alumina templates, which serve as substrates, respectively. By using a highly sensitive magneto-optical Kerr effect (MOKE) and vibrating sample magnetometer (VSM) measurements an interesting phenomenon has been observed, consisting in the easy magnetization axis transfer from a purely in-plane (INP) magnetic anisotropy to out-of-plane (OOP) magnetization. For the 30 nm film thickness we have measured the volume hysteresis loops by VSM with the easy magnetization axis lying along the OOP direction. Using magnetic force microscopy measurements (MFM), there is strong evidence to suggest that the formation of magnetic domains with OOP magnetization occurs in this sample. This phenomenon can be of high interest for the development of novel magnetic and magneto-optic perpendicular recording patterned media based on template-assisted deposition techniques. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Crosslinked Polymer Ionic Liquid/Ionic Liquid Blends Prepared by Photopolymerization as Solid-State Electrolytes in Supercapacitors
Nanomaterials 2018, 8(4), 225; https://doi.org/10.3390/nano8040225
Received: 8 February 2018 / Revised: 3 April 2018 / Accepted: 4 April 2018 / Published: 7 April 2018
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Abstract
A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and
[...] Read more.
A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br in PIL-M-(Br) and TFSI in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br and TFSI, respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g−1, 40 and 48 kW·kg−1, and 107 and 59.9 Wh·kg−1 were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Enhanced Supercapacitor Performance Using Electropolymerization of Self-Doped Polyaniline on Carbon Film
Nanomaterials 2018, 8(4), 214; https://doi.org/10.3390/nano8040214
Received: 8 February 2018 / Revised: 23 March 2018 / Accepted: 27 March 2018 / Published: 31 March 2018
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Abstract
In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid
[...] Read more.
In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid (SAN) comonomers in solution. Here, SAN acts in dual roles of a self-doped monomer while it also provides an acidic environment which is suitable for electropolymerization. The performance of SPANI−CNP-based supercapacitors significantly depends upon the mole ratio of AN/SAN. Supercapacitor performance was investigated by using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). The optimal performance of SPANI−CNP-based supercapacitor exists at AN/SAN ratio of 1.0, having the specific capacitance of 273.3 Fg−1 at the charging current density of 0.5 Ag−1. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessFeature PaperArticle Electrospun Composites of Polycaprolactone and Porous Silicon Nanoparticles for the Tunable Delivery of Small Therapeutic Molecules
Nanomaterials 2018, 8(4), 205; https://doi.org/10.3390/nano8040205
Received: 28 February 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
Cited by 1 | PDF Full-text (23921 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This report describes the use of an electrospun composite of poly(ε-caprolactone) (PCL) fibers and porous silicon (pSi) nanoparticles (NPs) as an effective system for the tunable delivery of camptothecin (CPT), a small therapeutic molecule. Both materials are biodegradable, abundant, low-cost, and most importantly,
[...] Read more.
This report describes the use of an electrospun composite of poly(ε-caprolactone) (PCL) fibers and porous silicon (pSi) nanoparticles (NPs) as an effective system for the tunable delivery of camptothecin (CPT), a small therapeutic molecule. Both materials are biodegradable, abundant, low-cost, and most importantly, have no known cytotoxic effects. The composites were treated with and without sodium hydroxide (NaOH) to investigate the wettability of the porous network for drug release and cell viability measurements. CPT release and subsequent cell viability was also investigated. We observed that the cell death rate was not only affected by the addition of our CPT carrier, pSi, but also by increasing the rate of dissolution via treatment with NaOH. This is the first example of loading pSi NPs as a therapeutics nanocarrier into electronspun PCL fibers and this system opens up new possibilities for the delivery of molecular therapeutics. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessArticle Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries
Nanomaterials 2017, 7(11), 368; https://doi.org/10.3390/nano7110368
Received: 26 September 2017 / Revised: 22 October 2017 / Accepted: 24 October 2017 / Published: 3 November 2017
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Abstract
To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide
[...] Read more.
To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C), good high-rate discharge capacity (118 mAh g−1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Open AccessFeature PaperArticle 3D Nanoporous Anodic Alumina Structures for Sustained Drug Release
Nanomaterials 2017, 7(8), 227; https://doi.org/10.3390/nano7080227
Received: 21 July 2017 / Accepted: 14 August 2017 / Published: 21 August 2017
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Abstract
The use of nanoporous anodic alumina (NAA) for the development of drug delivery systems has gained much attention in recent years. The release of drugs loaded inside NAA pores is complex and depends on the morphology of the pores. In this study, NAA,
[...] Read more.
The use of nanoporous anodic alumina (NAA) for the development of drug delivery systems has gained much attention in recent years. The release of drugs loaded inside NAA pores is complex and depends on the morphology of the pores. In this study, NAA, with different three-dimensional (3D) pore structures (cylindrical pores with several pore diameters, multilayered nanofunnels, and multilayered inverted funnels) were fabricated, and their respective drug delivery rates were studied and modeled using doxorubicin as a model drug. The obtained results reveal optimal modeling of all 3D pore structures, differentiating two drug release stages. Thus, an initial short-term and a sustained long-term release were successfully modeled by the Higuchi and the Korsmeyer–Peppas equations, respectively. This study demonstrates the influence of pore geometries on drug release rates, and further presents a sustained long-term drug release that exceeds 60 days without an undesired initial burst. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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Review

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Open AccessReview Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation
Nanomaterials 2018, 8(6), 379; https://doi.org/10.3390/nano8060379
Received: 31 March 2018 / Revised: 23 May 2018 / Accepted: 24 May 2018 / Published: 29 May 2018
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Abstract
Typically, anodic oxidation of metals results in the formation of hexagonally arranged nanoporous or nanotubular oxide, with a specific oxidation state of the transition metal. Recently, the majority of transition metals have been anodized; however, the formation of copper oxides by electrochemical oxidation
[...] Read more.
Typically, anodic oxidation of metals results in the formation of hexagonally arranged nanoporous or nanotubular oxide, with a specific oxidation state of the transition metal. Recently, the majority of transition metals have been anodized; however, the formation of copper oxides by electrochemical oxidation is yet unexplored and offers numerous, unique properties and applications. Nanowires formed by copper electrochemical oxidation are crystalline and composed of cuprous (CuO) or cupric oxide (Cu2O), bringing varied physical and chemical properties to the nanostructured morphology and different band gaps: 1.44 and 2.22 eV, respectively. According to its Pourbaix (potential-pH) diagram, the passivity of copper occurs at ambient and alkaline pH. In order to grow oxide nanostructures on copper, alkaline electrolytes like NaOH and KOH are used. To date, no systemic study has yet been reported on the influence of the operating conditions, such as the type of electrolyte, its temperature, and applied potential, on the morphology of the grown nanostructures. However, the numerous reports gathered in this paper will provide a certain view on the matter. After passivation, the formed nanostructures can be also post-treated. Post-treatments employ calcinations or chemical reactions, including the chemical reduction of the grown oxides. Nanostructures made of CuO or Cu2O have a broad range of potential applications. On one hand, with the use of surface morphology, the wetting contact angle is tuned. On the other hand, the chemical composition (pure Cu2O) and high surface area make such materials attractive for renewable energy harvesting, including water splitting. While compared to other fabrication techniques, self-organized anodization is a facile, easy to scale-up, time-efficient approach, providing high-aspect ratio one-dimensional (1D) nanostructures. Despite these advantages, there are still numerous challenges that have to be faced, including the strict control of the chemical composition and morphology of the grown nanostructures, their uniformity, and understanding the mechanism of their growth. Full article
(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)
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