Special Issue "Mesoporous Metal Oxide Films"

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (31 January 2020).

Special Issue Editor

Dr. Emmanuel Topoglidis
Website
Guest Editor
Department of Materials Science, University of Patras, Rion 26504, Greece
Interests: analytical chemistry; metal oxide films; coatings; colloids; nanoparticles; nanocomposites; perovskites; protein immobilization; bioelectrochemistry; electrochemical sensors and biosensors; cyclic voltammetry and chronoamperometry; optical biosensors; transient spectroscopy; potein/electrode interactions
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Special Issue Information

Dear Colleagues,

I would like to invite you to submit your work to this Special Issue on "Mesoporous Metal Oxide Films”. Mesoporous metal oxide films exhibit excellent physicochemical properties, such as large band gap, large surface area, controlable pore size and morphology, good thermal and chemical stabilities, unique optical and electrical properties, non-toxicity and low costs. Various techniques have been developed for the preparation of such films, including sol-gel screen printing, dip coating, spin coating, sputtering spray pyrolysis, atomic layer deposition, electrodeposition and anodic oxidation. A great deal of effort has been made to simplify these methods in order to prepare films faster and in a more reproducible way. Over the last 20 years, the films have been used for many applications ranging from dye-sensitized solar cells, adsorption and separation, chemical and biochemical sensors, gas sensors, drug delivery, electrochromic windows, photo and/or electrocatalysis and energy storage devices such as rechargeable batteries and electrochemical supercapacitors. More recently these materilas have beed used as the scaffold for the development of perovskite solar cells.  This Special Issue  of Coatings focuses on all these areas of application. Our aim is to present the most important developments in this fast-moving field, from the leading groups around the world.

Topics of interest include, but are not limited to:

  • Novel approaches of mesoporous metal oxide films related to fabrication and characterization methods;
  • Understand the optical and electronic properties of the films;
  • Their use for energy conersion and storage, for solar cells, as electrode material for lithium ion baterries and for electrochemical supercapacitors;
  • Gas sensing, studying their excellent sensing capabilities;
  • Their use as substrates for the immobilization of molecules or biomolecules for the development of electrochemical or optical sensors and biosensors;
  • Their use for adsorption and separation, as stationary phase in liquid chromatography or adsorbents for heavy metals, anions, organic pollutants and gases;
  • Their use as catalysts or catalyst supports, for studying redox reactions, for phtocatalytic applications etc.;
  • Their doping with nanoparticles, perovskites or other materials for multicolor photochromism, the development of more efficient solar cells or other applications.

Dr. Topoglidis Manos
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 papers will be 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. Coatings is an international peer-reviewed open access monthly 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 1600 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.

Published Papers (11 papers)

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Editorial

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Open AccessEditorial
Mesoporous Metal Oxide Films
Coatings 2020, 10(7), 668; https://doi.org/10.3390/coatings10070668 - 13 Jul 2020
Abstract
Great progress has been made in the preparation and application of mesoporous metal oxide films and materials during the last three decades. Numerous preparation methods and applications of these novel and interesting materials have been reported, and it was demonstrated that mesoporosity has [...] Read more.
Great progress has been made in the preparation and application of mesoporous metal oxide films and materials during the last three decades. Numerous preparation methods and applications of these novel and interesting materials have been reported, and it was demonstrated that mesoporosity has a direct impact on the properties and potential applications of such materials. This Special Issue of Coatings contains a series of ten research articles demonstrating emphatically that various metal oxide materials could be prepared using a number of different methods, and focuses on many areas where these mesoporous materials could be used, such as sensors, solar cells, supercapacitors, photoelectrodes, anti-corrosion agents and bioceramics. Our aim is to present important developments in this fast-moving field, from various groups around the world. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)

Research

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Open AccessEditor’s ChoiceArticle
Polyethylene Glycol (PEG) Modified Porous Ca5(PO4)2SiO4 Bioceramics: Structural, Morphologic and Bioactivity Analysis
Coatings 2020, 10(6), 538; https://doi.org/10.3390/coatings10060538 - 31 May 2020
Cited by 3
Abstract
Bioceramics are class of biomaterials that are specially developed for application in tissue engineering and regenerative medicines. Sol-gel method used for producing bioactive and reactive bioceramic materials more than those synthesized by traditional methods. In the present research study, the effect of polyethylene [...] Read more.
Bioceramics are class of biomaterials that are specially developed for application in tissue engineering and regenerative medicines. Sol-gel method used for producing bioactive and reactive bioceramic materials more than those synthesized by traditional methods. In the present research study, the effect of polyethylene glycol (PEG) on Ca5(PO4)2SiO4 (CPS) bioceramics was investigated. The addition of 5% and 10% PEG significantly affected the porosity and bioactivity of sol-gel derived Ca5(PO4)2SiO4. The morphology and physicochemical properties of pure and modified materials were evaluated using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR), respectively. The effect of PEG on the surface area and porosity of Ca5(PO4)2SiO4 was measured by Brunauer–Emmett–Teller (BET). The results obtained from XRD and FTIR studies confirmed the interactions between PEG and CPS. Due to the high concentration of PEG, the CPS-3 sample showed the largest-sized particle with an average of 200.53 µm. The porous structure of CPS-2 and CPS-3 revealed that they have a better ability to generate an appetite layer on the surface of the sample when immersed in simulated body fluid (SBF) for seven days. The generation of appetite layer showed the bioactive nature of CPS which makes it a suitable material for hard tissue engineering applications. The results have shown that the PEG-modified porous CPS could be a more effective material for drug delivery, implant coatings and other tissue engineering applications. The aim of this research work is to fabricate SBF treated and porous polyethylene glycol-modified Ca5(PO4)2SiO4 material. SBF treatment and porosity of material can provide a very useful target for bioactivity and drug delivery applications in the future. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessArticle
Anti-Corrosive Properties of an Effective Guar Gum Grafted 2-Acrylamido-2-Methylpropanesulfonic Acid (GG-AMPS) Coating on Copper in a 3.5% NaCl Solution
Coatings 2020, 10(3), 241; https://doi.org/10.3390/coatings10030241 - 05 Mar 2020
Cited by 3
Abstract
Guar gum grafted 2-acrylamido-2-methylpropanesulfonic acid (GG-AMPS) was synthesized using guar gum and AMPS as the base ingredients. The corrosion inhibition of copper was studied using weight loss, electrochemical, and surface characterization methods in a 3.5% sodium chloride (NaCl) solution. Studies including weight loss [...] Read more.
Guar gum grafted 2-acrylamido-2-methylpropanesulfonic acid (GG-AMPS) was synthesized using guar gum and AMPS as the base ingredients. The corrosion inhibition of copper was studied using weight loss, electrochemical, and surface characterization methods in a 3.5% sodium chloride (NaCl) solution. Studies including weight loss were done at different acid concentrations, different inhibitor concentrations, different temperatures, and different immersion times. The weight loss studies showed the good performance of GG-AMPS at a 600 mg/L concentration. This concentration was further used as the optimum concentration for all of the studies. The efficiency decreased with the rise in temperature and at higher concentrations of acidic media. However, the efficiency of the inhibition increased with the additional immersion time. Electrochemical methods including impedance and polarization were employed to calculate the inhibition efficiency. Both of the techniques exhibited a good inhibition by GG-APMS at a 600 mg/L concentration. Surface studies were conducted using scanning electrochemical microscopy (SECM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) methods. The surface studies showed smooth surfaces in the presence of GG-AMPS and rough surfaces in its absence. The adsorption type of GG-AMPS on the surface of the copper followed the Langmuir adsorption model. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessArticle
Increasing the Efficiency of Dye-Sensitized Solar Cells by Adding Nickel Oxide Nanoparticles to Titanium Dioxide Working Electrodes
Coatings 2020, 10(2), 195; https://doi.org/10.3390/coatings10020195 - 24 Feb 2020
Cited by 2
Abstract
In this study, nickel oxide (NiO) nanoparticles were added to a titanium dioxide (TiO2) nanoparticle paste to fabricate a dye-sensitized solar cell (DSSC) working electrode by using a screen-printing method. The effects of the NiO proportion in the TiO2 paste [...] Read more.
In this study, nickel oxide (NiO) nanoparticles were added to a titanium dioxide (TiO2) nanoparticle paste to fabricate a dye-sensitized solar cell (DSSC) working electrode by using a screen-printing method. The effects of the NiO proportion in the TiO2 paste on the TiO2 working electrode, DSSC devices, and electron transport characteristics were comprehensively investigated. The results showed that adding NiO nanoparticles to the TiO2 working electrode both inhibited electron transport (a negative effect) and prevented electron recombination with the electrolyte (a positive effect). The electron transit time was extended following an increase in the amount of NiO nanoparticles added, confirming that NiO inhibited electron transport. Furthermore, the energy level difference between TiO2 and NiO generated a potential barrier that prevented the recombination of the electrons in the TiO2 conduction band with the I3- ions in the electrolyte. When the TiO2–NiO ratio was 99:1, the positive effects outweighed the negative effects. Therefore, this ratio was the optimal TiO2–NiO ratio in the electrode for electron transport. The DSSCs with a TiO2–NiO (99:1) working electrode exhibited an optimal power conversion efficiency of 8.39%, which was higher than the DSSCs with a TiO2 working electrode. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
Iron-Doped Titanium Dioxide Nanoparticles As Potential Scaffold for Hydrazine Chemical Sensor Applications
Coatings 2020, 10(2), 182; https://doi.org/10.3390/coatings10020182 - 17 Feb 2020
Cited by 4
Abstract
Herein, we report the fabrication of a modified glassy carbon electrode (GCE) with high-performance hydrazine sensor based on Fe-doped TiO2 nanoparticles prepared via a facile and low-cost hydrothermal method. The structural morphology, crystalline, crystallite size, vibrational and scattering properties were examined through [...] Read more.
Herein, we report the fabrication of a modified glassy carbon electrode (GCE) with high-performance hydrazine sensor based on Fe-doped TiO2 nanoparticles prepared via a facile and low-cost hydrothermal method. The structural morphology, crystalline, crystallite size, vibrational and scattering properties were examined through different characterization techniques, including FESEM, XRD, FTIR, UV–Vis, Raman and photoluminescence spectroscopy. FESEM analysis revealed the high-density synthesis of Fe-doped TiO2 nanoparticles with the average diameter of 25 ± 5 nm. The average crystallite size of the synthesized nanoparticles was found to be around 14 nm. As-fabricated hydrazine chemical sensors exhibited 1.44 μA µM−1 cm−2 and 0.236 µM sensitivity and limit of detection (LOD), respectively. Linear dynamic ranged from 0.2 to 30 µM concentrations. Furthermore, the Fe-doped TiO2 modified GCE showed a negligible inference behavior towards ascorbic acid, uric acid, glucose, SO42−, NO3, Pb2+ and Ca2+ ions on the hydrazine sensing performance. Thus, Fe-doped TiO2 modified GCE can be efficiently used as an economical, easy to fabricate and selective sensing of hydrazine and its derivatives. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
Fully Reversible Electrically Induced Photochromic-Like Behaviour of Ag:TiO2 Thin Films
Coatings 2020, 10(2), 130; https://doi.org/10.3390/coatings10020130 - 03 Feb 2020
Cited by 2
Abstract
A TiO2 thin film, prepared on fluorine-doped indium tin oxide (FTO)-coated glass substrate, from commercial off-the-shelf terpinol-based paste, was used to directly adsorb Ag plasmonic nanoparticles capped with polyvinylpyrollidone (PVP) coating. The TiO2 film was sintered before the surface entrapment of [...] Read more.
A TiO2 thin film, prepared on fluorine-doped indium tin oxide (FTO)-coated glass substrate, from commercial off-the-shelf terpinol-based paste, was used to directly adsorb Ag plasmonic nanoparticles capped with polyvinylpyrollidone (PVP) coating. The TiO2 film was sintered before the surface entrapment of Ag nanoparticles. The composite was evaluated in terms of spectroelectrochemical measurements, cyclic voltammetry as well as structural methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the Ag nanoparticles are effectively adsorbed on the TiO2 film, while application of controlled voltages leads to a fully reversible shift of the plasmon peak from 413 nm at oxidation inducing voltages to 440 nm at reducing voltages. This phenomenon allows for the fabrication of a simple photonic switch at either or both wavelengths. The phenomenon of the plasmon shift is due to a combination of plasmon shift related to the form and dielectric environment of the nanoparticles. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessArticle
ZnO Nanocrystal-Based Chloroform Detection: Density Functional Theory (DFT) Study
Coatings 2019, 9(11), 769; https://doi.org/10.3390/coatings9110769 - 19 Nov 2019
Cited by 3
Abstract
We investigated the detection of chloroform (CHCl3) using ZnO nanoclusters via density functional theory calculations. The effects of various concentrations of CHCl3, as well as the deposition of O atoms, on the adsorption over ZnO nanoclusters were analyzed via [...] Read more.
We investigated the detection of chloroform (CHCl3) using ZnO nanoclusters via density functional theory calculations. The effects of various concentrations of CHCl3, as well as the deposition of O atoms, on the adsorption over ZnO nanoclusters were analyzed via geometric optimizations. The calculated difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for ZnO was 4.02 eV. The most stable adsorption characteristics were investigated with respect to the adsorption energy, frontier orbitals, elemental positions, and charge transfer. The results revealed that ZnO nanoclusters with a specific geometry and composition are promising candidates for chloroform-sensing applications. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
Ethylene Glycol Functionalized Gadolinium Oxide Nanoparticles as a Potential Electrochemical Sensing Platform for Hydrazine and p-Nitrophenol
Coatings 2019, 9(10), 633; https://doi.org/10.3390/coatings9100633 - 01 Oct 2019
Cited by 2
Abstract
The current work reports the successful synthesis of ethylene glycol functionalized gadolinium oxide nanoparticles (Gd2O3 Nps) as a proficient electrocatalytic material for the detection of hydrazine and p-nitrophenol. A facile hydrothermal approach was used for the controlled growth of Gd [...] Read more.
The current work reports the successful synthesis of ethylene glycol functionalized gadolinium oxide nanoparticles (Gd2O3 Nps) as a proficient electrocatalytic material for the detection of hydrazine and p-nitrophenol. A facile hydrothermal approach was used for the controlled growth of Gd2O3 Nps in the presence of ethylene glycol (EG) as a structure-controlling and hydrophilic coating source. The prepared material was characterized by several techniques in order to examine the structural, morphological, optical, photoluminescence, and sensing properties. The thermal stability, resistance toward corrosion, and decreased tendency toward photobleaching made Gd2O3 nanoparticles a good candidate for the electrochemical sensing of p-nitrophenol and hydrazine by using cyclic voltammetric (CV) and amperometric methods at a neutral pH range. The modified electrode possesses a linear range of 1 to 10 µM with a low detection limit of 1.527 and 0.704 µM for p-nitrophenol and hydrazine, respectively. The sensitivity, selectivity, repeatability, recyclability, linear range, detection limit, and applicability in real water samples made Gd2O3 Nps a favorable nanomaterial for the rapid and effectual scrutiny of harmful environmental pollutants. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
A Rapid Synthesis of Mesoporous Mn2O3 Nanoparticles for Supercapacitor Applications
Coatings 2019, 9(10), 631; https://doi.org/10.3390/coatings9100631 - 30 Sep 2019
Cited by 6
Abstract
Mn2O3 nanomaterials have been recently composing a variety of electrochemical systems like fuel cells, supercapacitors, etc., due to their high specific capacitance, low cost, abundance and environmentally benign nature. In this work, mesoporous Mn2O3 nanoparticles (NPs) were [...] Read more.
Mn2O3 nanomaterials have been recently composing a variety of electrochemical systems like fuel cells, supercapacitors, etc., due to their high specific capacitance, low cost, abundance and environmentally benign nature. In this work, mesoporous Mn2O3 nanoparticles (NPs) were synthesized by manganese acetate, citric acid and sodium hydroxide through a hydrothermal process at 150 °C for 3 h. The synthesized mesoporous Mn2O3 NPs were thoroughly characterized in terms of their morphology, surfaces, as well as their crystalline, electrochemical and electrochemical properties. For supercapacitor applications, the synthesized mesoporous Mn2O3 NP-based electrode accomplished an excellent specific capacitance (Csp) of 460 F·g−1 at 10 mV·s−1 with a good electrocatalytic activity by observing good electrochemical properties in a 6 M KOH electrolyte. The excellent Csp might be explained by the improvement of the surface area, porous surface and uniformity, which might favor the generation of large active sites and a fast ionic transport over the good electrocatalytic surface of the Mn2O3 electrode. The fabricated supercapacitors exhibited a good cycling stability after 5000 cycles by maintaining ~83% of Csp. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
Multi-Layered Mesoporous TiO2 Thin Films: Photoelectrodes with Improved Activity and Stability
Coatings 2019, 9(10), 625; https://doi.org/10.3390/coatings9100625 - 28 Sep 2019
Cited by 2
Abstract
This work aims at the identification of porous titanium dioxide thin film (photo)electrodes that represent suitable host structures for a subsequent electrodeposition of plasmonic nanoparticles. Sufficient UV absorption and electrical conductivity were assured by adjusting film thickness and TiO2 crystallinity. Films with [...] Read more.
This work aims at the identification of porous titanium dioxide thin film (photo)electrodes that represent suitable host structures for a subsequent electrodeposition of plasmonic nanoparticles. Sufficient UV absorption and electrical conductivity were assured by adjusting film thickness and TiO 2 crystallinity. Films with up to 10 layers were prepared by an evaporation-induced self-assembly (EISA) method and layer-by-layer deposition. Activities were tested towards the photoelectrochemical oxidation of water under UV illumination. Enhanced activities with each additional layer were observed and explained with increased amounts of immobilized TiO 2 and access to more active sites as a combined effect of increased surface area, better crystallinity and improved transport properties. Furthermore, films display good electrochemical and mechanical stability, which was related to the controlled intermediate thermal annealing steps, making these materials a promising candidate for future electrochemical depositions of plasmonic noble metal nanoparticles that has been further demonstrated by incorporation of gold. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessFeature PaperArticle
Hemin-Modified SnO2/Metglas Electrodes for the Simultaneous Electrochemical and Magnetoelastic Sensing of H2O2
Coatings 2018, 8(8), 284; https://doi.org/10.3390/coatings8080284 - 16 Aug 2018
Cited by 4
Abstract
In this work, we present a simple and efficient method for the preparation of hemin-modified SnO2 films on Metglas ribbon substrates for the development of a sensitive magneto-electrochemical sensor for the determination of H2O2. The SnO2 films [...] Read more.
In this work, we present a simple and efficient method for the preparation of hemin-modified SnO2 films on Metglas ribbon substrates for the development of a sensitive magneto-electrochemical sensor for the determination of H2O2. The SnO2 films were prepared at low temperatures, using a simple hydrothermal method, compatible with the Metglas surface. The SnO2 film layer was fully characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), photoluminescence (PL) and Fourier Transform-Infrared spectroscopy (FT-IR). The properties of the films enable a high hemin loading to be achieved in a stable and functional way. The Hemin/SnO2-Metglas system was simultaneously used as a working electrode (WE) for cyclic voltammetry (CV) measurements and as a magnetoelastic sensor excited by external coils, which drive it to resonance and interrogate it. The CV scans reveal direct reduction and oxidation of the immobilized hemin, as well as good electrocatalytic response for the reduction of H2O2. In addition, the magnetoelastic resonance (MR) technique allows the detection of any mass change during the electroreduction of H2O2 by the immobilized hemin on the Metglas surface. The experimental results revealed a mass increase on the sensor during the redox reaction, which was calculated to be 767 ng/μM. This behavior was not detected during the control experiment, where only the NaH2PO4 solution was present. The following results also showed a sensitive electrochemical sensor response linearly proportional to the concentration of H2O2 in the range 1 × 10−6–72 × 10−6 M, with a correlation coefficient of 0.987 and detection limit of 1.6 × 10−7 M. Moreover, the Hemin/SnO2-Metglas displayed a rapid response (30 s) to H2O2 and exhibits good stability, reproducibility and selectivity. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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