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Crystals
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Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications
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Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (15 April 2024) | Viewed by 8385

Special Issue Editors

Prof. Dr. Abdelhamid El-Shaer

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Guest Editor
Physics Department, Faculty of Science, Kafrelsheikh University, Kafrel-Sheikh 33516, Egypt
Interests: hydrothermal; electrodeposition; nanostructures; semiconductor; thin films; photoelectrochemical; biosensor; solar cell; energy storage; supercapacitors; electrical, optical, structural, morphological properties; photoelectrochemical properties; solar cells; LEDs devices
Dr. Mahmoud S. Abdelfatah

E-Mail Website
Guest Editor
Department of Physics, Faculty of Science, Kafrelsheikh University, Kafrelsheikh 33516, Egypt
Interests: hydrothermal; electrodeposition; nanostructures; semiconductor; thin films; photoelectrochemical; biosensor; solar cell; energy storage; supercapacitors; electrical, optical, structural, morphological properties; photoelectrochemical properties; solar cells; LEDs devices
Prof. Dr. Magdy said Abo Ghazala

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Guest Editor
Physics Department, Faculty of Science, Menoufia University, Menoufia 32511, Egypt
Interests: material science
Dr. Mohammed Shihab

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Guest Editor
Physics Department, Faculty of Science, Tanta University, Tanta 31527, Egypt
Interests: low temperature plasma; RF capacitive coupled plasma; RF magnetron; RF inductive coupled plasma; atmospheric plasma jets; plasma modelling and simulation; plasma etching and deposition; semiconductor fabrication; waves; laser matter interactions; density functional theory
Dr. Mohamed EL-Henawey

E-Mail Website
Guest Editor
Physics Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
Interests: polymer composites; semiconductor materials; thin films; energy harvesting materials; optoelectronics; oxides-based solar cells; LEDs; organic solar cells and perovskite solar cells

Special Issue Information

Dear Colleagues,

Innovations in sustainable energy technologies and environmental applications significantly depend on our ability to assemble and recognize nanomaterials of metal oxides, especially semiconductors with optimal properties. Therefore, the theoretical and experimental studies of such metal oxides, their heterojunction and nanocomposites for energy harvesting and environmental applications. So, fabrication (including low-cost methods and techniques) and characterization (including the electrical, optical, structural, and morphological properties) of such metal oxide nanomaterials is our aim to use multifunction in various energy, optoelectronics and environmental application like supercapacitors, solar cells, LEDs devices, wastewater treatment, antimicrobial, cancer imaging, drug delivery, and biosensors applications.

The main contribution of the present Special Issue is “Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications”. We believe that this issue is theoretically and practically needed at present to discover outstanding future devices.

Prof. Dr. Abdelhamid El-Shaer
Dr. Mahmoud S. Abdelfatah
Prof. Dr. Magdy said Abo Ghazala
Dr. Mohammed Shihab
Dr. Mohamed EL-Henawey
Guest Editors

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. Crystals 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 2100 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

  • fabrication (including low-cost methods and techniques)
  • characterization of metal oxide nanomaterials and semiconductors
  • theoretical Investigations
  • simulations and modeling
  • hydrothermal
  • electrodeposition
  • nanostructures
  • semiconductor
  • thin films
  • electrical, optical, properties
  • structural, morphological properties
  • photoelectrochemical properties
  • biosensor
  • solar cells
  • energy storage
  • supercapacitors
  • LEDs devices
  • wastewater treatment
  • antimicrobial, cancer imaging, and drug delivery applications

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Published Papers (5 papers)

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Research

18 pages, 9164 KiB  
Article
Enhancing Photovoltaic Performance with BaTiO3/MWCNTs Composite Photoelectrodes in Dye-Sensitized Solar Cells
by Carlos Armando Polo Bravo, Brayan Yeraldyn Caceres Osnayo, Jesús Alfredo Chacaltana García, Jesús Plácido Medina Salas, Francisco Gamarra Gómez, Hugo Alfredo Torres Muro, Alberto Bacilio Quispe Cohaila, Ramalinga Viswanathan Mangalaraja and Elisban Juani Sacari Sacari
Crystals 2024, 14(6), 489; https://doi.org/10.3390/cryst14060489 - 23 May 2024
Cited by 2 | Viewed by 1514
Abstract
Dye-sensitized solar cells (DSSCs) have attracted renewed research interest as a potential low-cost substitute for conventional silicon photovoltaics. This work aims to improve the photovoltaic performance of the DSSCs by incorporating multi-walled carbon nanotubes (MWCNTs) into the BaTiO3 photoelectrode. The pure BaTiO [...] Read more.
Dye-sensitized solar cells (DSSCs) have attracted renewed research interest as a potential low-cost substitute for conventional silicon photovoltaics. This work aims to improve the photovoltaic performance of the DSSCs by incorporating multi-walled carbon nanotubes (MWCNTs) into the BaTiO3 photoelectrode. The pure BaTiO3 and BaTiO3/MWCNT nanocomposites were sensitized with N719 dye and fabricated into solar cell devices for testing. The structural characterization confirmed the successful formation of the nanocomposite with an optimal dispersion at 6% of MWCNT incorporation, beyond which agglomeration effects manifested. The optical analysis verified the modulation of defect states and bandgap engineering induced by the MWCNT network. The morphological studies revealed irregular nanoparticle clusters with embedded nanotubes. Solar cell testing under AM1.5G-simulated sunlight demonstrated a peak power conversion efficiency of 4.044% for 6% of MWCNT doping, constituting a 6-fold increment versus pure BaTiO3 (0.693%). It originated from the simultaneous enhancements in the open-circuit voltage and short-circuit current enabled by the favorable band structure alterations and percolation-assisted charge transport. However, further increasing MWCNT content deteriorated the device metrics, owing to emerging limitations like trapping. The rational integration of multi-walled carbon nanotubes with lead-free ferroelectric metal oxides can contribute to the development of emerging organic-inorganic hybrid solar platforms. Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
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23 pages, 2836 KiB  
Article
Effect of Changing and Combining Trivalent Metals in the Structural and Electronic Properties of Cu-Based Crystal Delafossite Materials
by Joeluis Cerutti Torres, Pablo Sánchez-Palencia, José Carlos Jiménez-Sáez, Perla Wahnón and Pablo Palacios
Crystals 2024, 14(5), 418; https://doi.org/10.3390/cryst14050418 - 29 Apr 2024
Viewed by 1068
Abstract
Cu-based ternary oxides with delafossite structure have received considerable attention in recent years for their versatility in a wide range of applications, among which is the possibility to use them in heterostructure solar cells as hole transport layers, due to their promising behavior [...] Read more.
Cu-based ternary oxides with delafossite structure have received considerable attention in recent years for their versatility in a wide range of applications, among which is the possibility to use them in heterostructure solar cells as hole transport layers, due to their promising behavior as p-type conducting oxides. Ab initio calculations have been performed with density functional theory to investigate the role of the trivalent metal within the CuMO2 structure and the dependence of structural and electronic properties with the species (M = Al, Ga, In, Fe, Cr, Co, Sc, Y) occupying the site of the metal. Generalized Gradient Approximation also including a Hubbard term and nonlocal Heyd–Scuseria–Enzerhof screened hybrid functional schemes were tested and their results were compared. Excellent agreement with experimental lattice parameters and measured gaps have been found. The use of hybrid functionals in HSE approximation considerably improves the bandgaps when compared with the experimental results but takes considerable time to converge, hence the need to explore less demanding methodologies. Trends in the geometry as well as in the electronic properties are discussed, and the effect of mixing different metals (CuMxN1−xO2, M, N being the aforementioned elements) in the geometry and electronic properties of these delafossite materials is investigated. Due to the high cost of HSE calculations, especially when supercells are needed to model several x concentrations, statistical models and techniques based on machine learning have also been explored to predict HSE bandgap values from GGA and structural information. Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
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11 pages, 3346 KiB  
Article
The Impact of Temperature and Power Variation on the Optical, Wettability, and Anti-Icing Characteristics of AZO Coatings
by Kamlesh V. Chauhan, Sushant Rawal, Nicky P. Patel and Vandan Vyas
Crystals 2024, 14(4), 368; https://doi.org/10.3390/cryst14040368 - 15 Apr 2024
Viewed by 1266
Abstract
The structural, wettability, and optical characteristics of aluminum-doped zinc oxide (AZO) thin films were studied with the objective of understanding the impact of deposition power and deposition temperature. Thin films were deposited using a radio frequency (RF) magnetron sputtering technique. The power output [...] Read more.
The structural, wettability, and optical characteristics of aluminum-doped zinc oxide (AZO) thin films were studied with the objective of understanding the impact of deposition power and deposition temperature. Thin films were deposited using a radio frequency (RF) magnetron sputtering technique. The power output of the RF was augmented from 200 to 260 W, and the temperature was increased from 50 to 200 °C, which led to the development of a (002) peak for zinc oxide. The study of film thickness was carried out using the Swanepoel envelope method from data obtained through the UV-Vis spectrum. An increase in surface roughness value was shown to be connected with fluctuations in temperature as well as increases in deposition power. The findings revealed that as deposition power and temperature increased, the value of optical transmittance decreased, ranging from 70% to 90% based on the deposition parameters within the range of wavelengths that extend from 300 to 800 nm. The wettability properties of the samples were studied, and the maximum contact angle achieved was 110°. A Peltier apparatus was utilised in order to investigate the anti-icing capabilities, which revealed that the icing process was slowed down 3.38-fold. This work extends the understanding of the hydrophobicity and anti-icing capabilities of AZO thin films, specifically increasing both attributes which provide feasible options for purposes requiring resistance to ice. Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
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13 pages, 5048 KiB  
Article
Structural Analysis, Characterization, and First-Principles Calculations of Bismuth Tellurium Oxides, Bi6Te2O15
by Sun Woo Kim and Hong Young Chang
Crystals 2024, 14(1), 23; https://doi.org/10.3390/cryst14010023 - 26 Dec 2023
Viewed by 1409
Abstract
A single crystal of Bi6Te2O15 was obtained from the melt of the solid-state reaction of Bi2O3 and TeO3. Bi6Te2O15 crystallizes in the Pnma space group (No. 62) and [...] Read more.
A single crystal of Bi6Te2O15 was obtained from the melt of the solid-state reaction of Bi2O3 and TeO3. Bi6Te2O15 crystallizes in the Pnma space group (No. 62) and exhibits a three-dimensional network structure with a =10.5831(12) Å, b = 22.694(3) Å, c = 5.3843(6) Å, α = β = γ = 90°, V = 1293.2(3) Å3, and Z = 4. The structure was determined using single-crystal X-ray diffraction. An asymmetric unit in the unit cell, Bi3Te1O7.5, uniquely composed of four Bi3+ sites, one Te6+ site, and nine O2− sites, was solved and refined. As a bulk phase, Bi6Te2O15 was also synthesized and characterized using powder X-ray diffraction (XRD), infrared (FT-IR) spectrometry, and the thermogravimetric analysis (TGA) method. Through bond valence sum (BVS) calculations from the single crystal structure, Bi and Te cations have +3 and +6 oxidation numbers, respectively. Each Bi3+ cation forms a square pyramidal structure with five O2− anions, and a single Te6+ cation forms a six-coordinated octahedral structure with O2− anions. Since the lone-pair electron (Lp) of the square pyramidal structure, [BiO5]7−, where the Bi+ cation occupies the center of the square base plane, exists in the opposite direction of the square plane, the asymmetric environments of all four Bi3+ cations were analyzed and explored by determining the local dipole moments. In addition, to determine the extent of bond strain and distortion in the unit cell, which is attributed to the asymmetric environments of the Bi3+ and Te6+ cations in Bi6Te2O15, bond strain index (BSI) and global instability index (GII) were also calculated. We also investigated the structural, electronic, and optical properties of the structure of Bi6Te2O15 using the full potential linear augmented plane wave (FP-LAPW) method and the density functional theory (DFT) with WIEN2k code. In order to study the ground state properties of Bi6Te2O15, the theoretical total energies were calculated as a function of reduced volumes and then fitted with the Birch–Murnaghan equation of state (EOS). The band gap energy within the modified Becke–Johnson potential with Tran–Blaha parameterization (TB-mBJ) revealed a value of 3.36 eV, which was higher than the experimental value of 3.29 eV. To explore the optical properties of Bi6Te2O15, the real and imaginary parts of the dielectric function, refraction index, optical absorption coefficient, reflectivity, the real part of the optical conductivity extinction function, and the energy loss function were also calculated. Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
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14 pages, 5734 KiB  
Article
Influence of Deposition Time on Structural, Morphological, and Optical Properties of CdS Thin Films Grown by Low-Cost Chemical Bath Deposition
by Abdelhamid El-Shaer, Sameh Ezzat, Mohamed A. Habib, Omar K. Alduaij, Talaat M. Meaz and Samy A. El-Attar
Crystals 2023, 13(5), 788; https://doi.org/10.3390/cryst13050788 - 9 May 2023
Cited by 12 | Viewed by 2427
Abstract
CdS thin films were deposited on glass substrates employing low-cost and low-temperature chemical bath deposition (CBD). The effect of deposition time on the fabricated sample’s properties was investigated by XRD, SEM, EDX, Raman, UV-vis spectrophotometry, and PL spectroscopy. XRD results indicate the formation [...] Read more.
CdS thin films were deposited on glass substrates employing low-cost and low-temperature chemical bath deposition (CBD). The effect of deposition time on the fabricated sample’s properties was investigated by XRD, SEM, EDX, Raman, UV-vis spectrophotometry, and PL spectroscopy. XRD results indicate the formation of cubic and hexagonal structures of CdS thin films. The calculated average crystal size ranged from 21–50 nm. SEM results indicate the formation of hierarchical nanoflakes where the nanoflakes are entangled with one another like plant roots. Raman study confirmed that the fabricated thin films have two distinct peaks that are centered at 298 cm−1 and 599 cm−1, which are characteristic vibration modes for CdS thin film. UV-vis absorption spectra indicate absorption band edges near 500 nm, which are related to the band gap values of CdS thin films. The estimated Eg of CdS thin films was reduced from 2.4 to 2.22 eV as the deposition time increased from 5 to 60 min. PL results show the main peak centered at 537 nm, its intensity decreasing as deposition time increases, indicating lower recombination of charge carriers. Our results reveal that CdS thin films are an excellent candidate for optoelectronic applications. Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
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