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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Review

24 pages, 4351 KiB  
Review
Developing Insulating Polymeric Foams: Strategies and Research Needs from a Circular Economy Perspective
by Lucia Doyle, Ingo Weidlich and Ernesto Di Maio
Materials 2022, 15(18), 6212; https://doi.org/10.3390/ma15186212 - 7 Sep 2022
Cited by 16 | Viewed by 4108
Abstract
Insulating polymeric foams have an important role to play in increasing energy efficiency and therefore contributing to combating climate change. Their development in recent years has been driven towards the reduction of thermal conductivity and achievement of the required mechanical properties as main [...] Read more.
Insulating polymeric foams have an important role to play in increasing energy efficiency and therefore contributing to combating climate change. Their development in recent years has been driven towards the reduction of thermal conductivity and achievement of the required mechanical properties as main targets towards sustainability. This perception of sustainability has overseen the choice of raw materials, which are often toxic, or has placed research efforts on optimizing one constituent while the other necessary reactants remain hazardous. The transition to the circular economy requires a holistic understanding of sustainability and a shift in design methodology and the resulting research focus. This paper identifies research needs and possible strategies for polymeric foam development compatible with Circular Product Design and Green Engineering, based on an extensive literature review. Identified research needs include material characterization of a broader spectrum of polymer melt–gas solutions, ageing behavior, tailoring of the polymer chains, detailed understanding and modeling of the effects of shear on cell nucleation, and the upscaling of processing tools allowing for high and defined pressure drop rates. Full article
(This article belongs to the Special Issue Polymer Foams: Materials, Processing and Properties)
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32 pages, 3128 KiB  
Review
Lignin as a Renewable Building Block for Sustainable Polyurethanes
by Fernanda Rosa Vieira, Sandra Magina, Dmitry V. Evtuguin and Ana Barros-Timmons
Materials 2022, 15(17), 6182; https://doi.org/10.3390/ma15176182 - 5 Sep 2022
Cited by 39 | Viewed by 7258
Abstract
Currently, the pulp and paper industry generates around 50–70 million tons of lignin annually, which is mainly burned for energy recovery. Lignin, being a natural aromatic polymer rich in functional hydroxyl groups, has been drawing the interest of academia and industry for its [...] Read more.
Currently, the pulp and paper industry generates around 50–70 million tons of lignin annually, which is mainly burned for energy recovery. Lignin, being a natural aromatic polymer rich in functional hydroxyl groups, has been drawing the interest of academia and industry for its valorization, especially for the development of polymeric materials. Among the different types of polymers that can be derived from lignin, polyurethanes (PUs) are amid the most important ones, especially due to their wide range of applications. This review encompasses available technologies to isolate lignin from pulping processes, the main approaches to convert solid lignin into a liquid polyol to produce bio-based polyurethanes, the challenges involving its characterization, and the current technology assessment. Despite the fact that PUs derived from bio-based polyols, such as lignin, are important in contributing to the circular economy, the use of isocyanate is a major environmental hot spot. Therefore, the main strategies that have been used to replace isocyanates to produce non-isocyanate polyurethanes (NIPUs) derived from lignin are also discussed. Full article
(This article belongs to the Special Issue Synthesis and Application of New Lignin-Based Polymers and Composites)
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17 pages, 3368 KiB  
Review
Direct Writing of Functional Layer by Selective Laser Sintering of Nanoparticles for Emerging Applications: A Review
by Eunseung Hwang, Jungmin Hong, Jonghun Yoon and Sukjoon Hong
Materials 2022, 15(17), 6006; https://doi.org/10.3390/ma15176006 - 31 Aug 2022
Cited by 13 | Viewed by 3640
Abstract
Selective laser sintering of nanoparticles enables the direct and rapid formation of a functional layer even on heat-sensitive flexible and stretchable substrates, and is rising as a pioneering fabrication technology for future-oriented applications. To date, laser sintering has been successfully applied to various [...] Read more.
Selective laser sintering of nanoparticles enables the direct and rapid formation of a functional layer even on heat-sensitive flexible and stretchable substrates, and is rising as a pioneering fabrication technology for future-oriented applications. To date, laser sintering has been successfully applied to various target nanomaterials including a wide range of metal and metal-oxide nanoparticles, and extensive investigation of relevant experimental schemes have not only reduced the minimum feature size but also have further expanded the scalability of the process. In the beginning, the selective laser sintering process was regarded as an alternative method to conventional manufacturing processes, but recent studies have shown that the unique characteristics of the laser-sintered layer may improve device performance or even enable novel functionalities which were not achievable using conventional fabrication techniques. In this regard, we summarize the current developmental status of the selective laser sintering technique for nanoparticles, affording special attention to recent emerging applications that adopt the laser sintering scheme. Full article
(This article belongs to the Special Issue Feature Paper in Section Smart Materials)
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24 pages, 6512 KiB  
Review
Irradiation-Induced Amorphous-to-Crystalline Phase Transformations in Ceramic Materials
by Cyrus Koroni, Tristan Olsen, Janelle P. Wharry and Hui Xiong
Materials 2022, 15(17), 5924; https://doi.org/10.3390/ma15175924 - 27 Aug 2022
Cited by 15 | Viewed by 3884
Abstract
Amorphous ceramics are a unique class of materials with unusual properties and functionalities. While these materials are known to crystallize when subjected to thermal annealing, they have sometimes been observed to crystallize athermally when exposed to extreme irradiation environments. Because irradiation is almost [...] Read more.
Amorphous ceramics are a unique class of materials with unusual properties and functionalities. While these materials are known to crystallize when subjected to thermal annealing, they have sometimes been observed to crystallize athermally when exposed to extreme irradiation environments. Because irradiation is almost universally understood to introduce disorder into materials, these observations of irradiation-induced ordering or crystallization are unusual and may partially explain the limited research into this phenomenon. However, the archival literature presents a growing body of evidence of these irradiation-induced amorphous-to-crystalline (a-to-c) phase transformations in ceramics. In this perspective, the summary and review of examples from the literature of irradiation-induced a-to-c transformations for various classifications of ceramics are provided. This work will highlight irradiation conditions and material parameters that appear most influential for activating a-to-c transformations, identify trends, examine possible mechanisms, and discuss the impact of a-to-c transformations on material properties. Finally, future research directions that will enable researchers to harness a-to-c transformations to tailor materials behaviors will be provided. Full article
(This article belongs to the Special Issue Radiation Damage in Materials: Coupled Extreme Environments)
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16 pages, 4687 KiB  
Review
A Mini Review on Persulfate Activation by Sustainable Biochar for the Removal of Antibiotics
by Mengxue Li, Peng Li, Qi Zhou and Stephanie Ling Jie Lee
Materials 2022, 15(17), 5832; https://doi.org/10.3390/ma15175832 - 24 Aug 2022
Cited by 20 | Viewed by 3545
Abstract
Antibiotic contamination in water bodies poses ecological risks to aquatic organisms and humans and is a global environmental issue. Persulfate-based advanced oxidation processes (PS-AOPs) are efficient for the removal of antibiotics. Sustainable biochar materials have emerged as potential candidates as persulfates (Peroxymonosulfate (PMS) [...] Read more.
Antibiotic contamination in water bodies poses ecological risks to aquatic organisms and humans and is a global environmental issue. Persulfate-based advanced oxidation processes (PS-AOPs) are efficient for the removal of antibiotics. Sustainable biochar materials have emerged as potential candidates as persulfates (Peroxymonosulfate (PMS) and Peroxydisulfate (PDS)) activation catalysts to degrade antibiotics. In this review, the feasibility of pristine biochar and modified biochar (non-metal heteroatom-doped biochar and metal-loaded biochar) for the removal of antibiotics in PS-AOPs is evaluated through a critical analysis of recent research. The removal performances of biochar materials, the underlying mechanisms, and active sites involved in the reactions are studied. Lastly, sustainability considerations for future biochar research, including Sustainable Development Goals, technical feasibility, toxicity assessment, economic and life cycle assessment, are discussed to promote the large-scale application of biochar/PS technology. This is in line with the global trends in ensuring sustainable production. Full article
(This article belongs to the Special Issue Progress in Carbon-Based Materials)
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56 pages, 7034 KiB  
Review
Color Conversion Light-Emitting Diodes Based on Carbon Dots: A Review
by Danilo Trapani, Roberto Macaluso, Isodiana Crupi and Mauro Mosca
Materials 2022, 15(15), 5450; https://doi.org/10.3390/ma15155450 - 8 Aug 2022
Cited by 21 | Viewed by 4288
Abstract
This paper reviews the state-of-the-art technologies, characterizations, materials (precursors and encapsulants), and challenges concerning multicolor and white light-emitting diodes (LEDs) based on carbon dots (CDs) as color converters. Herein, CDs are exploited to achieve emission in LEDs at wavelengths longer than the pump [...] Read more.
This paper reviews the state-of-the-art technologies, characterizations, materials (precursors and encapsulants), and challenges concerning multicolor and white light-emitting diodes (LEDs) based on carbon dots (CDs) as color converters. Herein, CDs are exploited to achieve emission in LEDs at wavelengths longer than the pump wavelength. White LEDs are typically obtained by pumping broad band visible-emitting CDs by an UV LED, or yellow–green-emitting CDs by a blue LED. The most important methods used to produce CDs, top-down and bottom-up, are described in detail, together with the process that allows one to embed the synthetized CDs on the surface of the pumping LEDs. Experimental results show that CDs are very promising ecofriendly candidates with the potential to replace phosphors in traditional color conversion LEDs. The future for these devices is bright, but several goals must still be achieved to reach full maturity. Full article
(This article belongs to the Special Issue Organic Materials for Electronic and Optoelectronic Applications)
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23 pages, 2784 KiB  
Review
Comparison between Piezoelectric and Piezoresistive Wearable Gait Monitoring Techniques
by Zhiyuan Zhang, Zhenyu Xu, Wenbin Chen and Shuo Gao
Materials 2022, 15(14), 4837; https://doi.org/10.3390/ma15144837 - 12 Jul 2022
Cited by 9 | Viewed by 3641
Abstract
Insole plantar stress detection (PSD) techniques play an important role in gait monitoring. Among the various insole PSD methods, piezoelectric- and piezoresistive-based architectures are broadly used in medical scenes. Each year, a growing number of new research outcomes are reported. Hence, a deep [...] Read more.
Insole plantar stress detection (PSD) techniques play an important role in gait monitoring. Among the various insole PSD methods, piezoelectric- and piezoresistive-based architectures are broadly used in medical scenes. Each year, a growing number of new research outcomes are reported. Hence, a deep understanding of these two kinds of insole PSD sensors and state-of-the-art work would strongly benefit the researchers in this highly interdisciplinary field. In this context, this review article is composed of the following aspects. First, the mechanisms of the two techniques and corresponding comparisons are explained and discussed. Second, advanced materials which could enhance the performance of current piezoelectric and piezoresistive insole prototypes are introduced. Third, suggestions for designing insole PSD prototypes/products for different diseases are offered. Last, the current challenge and potential future trends are provided. Full article
(This article belongs to the Special Issue Functional Materials Based Human-Machine Interactivities)
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24 pages, 4319 KiB  
Review
A Comparative Mini-Review on Transition Metal Oxides Applied for the Selective Catalytic Ammonia Oxidation (NH3-SCO)
by Magdalena Jabłońska and Alejandro Mollá Robles
Materials 2022, 15(14), 4770; https://doi.org/10.3390/ma15144770 - 7 Jul 2022
Cited by 17 | Viewed by 3985
Abstract
The selective catalytic oxidation of NH3 (NH3-SCO) into N2 and H2O is an efficient technology for NH3 abatement in diesel vehicles. However, the catalysts dedicated to NH3-SCO are still under development. One of the [...] Read more.
The selective catalytic oxidation of NH3 (NH3-SCO) into N2 and H2O is an efficient technology for NH3 abatement in diesel vehicles. However, the catalysts dedicated to NH3-SCO are still under development. One of the groups of such catalysts constituted transition metal-based catalysts, including hydrotalcite-derived mixed metal oxides. This class of materials is characterized by tailored composition, homogenously dispersed mixed metal oxides, exhibiting high specific surface area and thermal stability. Thus, firstly, we give a short introduction to the structure and composition of hydrotalcite-like materials and their applications in NH3-SCO. Secondly, an overview of other transition metal-based catalysts reported in the literature is given, following a comparison of both groups. The challenges in NH3-SCO applications are provided, while the reaction mechanisms are discussed for particular systems. Full article
(This article belongs to the Section Catalytic Materials)
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25 pages, 4132 KiB  
Review
Magnetic Metal Oxide-Based Photocatalysts with Integrated Silver for Water Treatment
by George V. Belessiotis, Pinelopi P. Falara, Islam Ibrahim and Athanassios G. Kontos
Materials 2022, 15(13), 4629; https://doi.org/10.3390/ma15134629 - 1 Jul 2022
Cited by 39 | Viewed by 4397
Abstract
In this review, the most recent advances in the field of magnetic composite photocatalysts with integrated plasmonic silver (Ag) is presented, with an overview of their synthesis techniques, properties and photocatalytic pollutant removal applications. Magnetic attributes combined with plasmonic properties in these composites [...] Read more.
In this review, the most recent advances in the field of magnetic composite photocatalysts with integrated plasmonic silver (Ag) is presented, with an overview of their synthesis techniques, properties and photocatalytic pollutant removal applications. Magnetic attributes combined with plasmonic properties in these composites result in enhancements for light absorption, charge-pair generation-separation-transfer and photocatalytic efficiency with the additional advantage of their facile magnetic separation from water solutions after treatment, neutralizing the issue of silver’s inherent toxicity. A detailed overview of the currently utilized synthesis methods and techniques for the preparation of magnetic silver-integrated composites is presented. Furthermore, an extended critical review of the most recent pollutant removal applications of these composites via green photocatalysis technology is presented. From this survey, the potential of magnetic composites integrated with plasmonic metals is highlighted for light-induced water treatment and purification. Highlights: (1) Perspective of magnetic properties combined with plasmon metal attributes; (2) Overview of recent methods for magnetic silver-integrated composite synthesis; (3) Critical view of recent applications for photocatalytic pollutant removal. Full article
(This article belongs to the Section Materials Physics)
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25 pages, 1420 KiB  
Review
Strongly Correlated Quantum Spin Liquids versus Heavy Fermion Metals: A Review
by Vasily R. Shaginyan, Alfred Z. Msezane, George S. Japaridze, Stanislav A. Artamonov and Yulya S. Leevik
Materials 2022, 15(11), 3901; https://doi.org/10.3390/ma15113901 - 30 May 2022
Cited by 2 | Viewed by 2670
Abstract
This review considers the topological fermion condensation quantum phase transition (FCQPT) that explains the complex behavior of strongly correlated Fermi systems, such as frustrated insulators with quantum spin liquid and heavy fermion metals. The review contrasts theoretical consideration with recent experimental data collected [...] Read more.
This review considers the topological fermion condensation quantum phase transition (FCQPT) that explains the complex behavior of strongly correlated Fermi systems, such as frustrated insulators with quantum spin liquid and heavy fermion metals. The review contrasts theoretical consideration with recent experimental data collected on both heavy fermion metals (HF) and frustrated insulators. Such a method allows to understand experimental data. We also consider experimental data collected on quantum spin liquid in Lu3Cu2Sb3O14 and quasi-one dimensional (1D) quantum spin liquid in both YbAlO3 and Cu(C4H4N2)(NO3)2 with the aim to establish a sound theoretical explanation for the observed scaling laws, Landau Fermi liquid (LFL) and non-Fermi-liquid (NFL) behavior exhibited by these frustrated insulators. The recent experimental data on the heavy-fermion metal α−YbAl1−xFexB4, with x=0.014, and on its sister compounds β−YbAlB4 and YbCo2Ge4, carried out under the application of magnetic field as a control parameter are analyzed. We show that the thermodynamic and transport properties as well as the empirical scaling laws follow from the fermion condensation theory. We explain how both the similarity and the difference in the thermodynamic and transport properties of α−YbAl1−xFexB4 and in its sister compounds β−YbAlB4 and YbCo2Ge4 emerge, as well as establish connection of these (HF) metals with insulators Lu3Cu2Sb3O14, Cu(C4H4N2)(NO3)2 and YbAlO3. We demonstrate that the universal LFL and NFL behavior emerge because the HF compounds and the frustrated insulators are located near the topological FCQPT or are driven by the application of magnetic fields. Full article
(This article belongs to the Special Issue Exploration of Novel Quantum Spin Liquid Materials)
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31 pages, 1474 KiB  
Review
A Comprehensive Analysis of the UVC LEDs’ Applications and Decontamination Capability
by Talita Nicolau, Núbio Gomes Filho, Jorge Padrão and Andrea Zille
Materials 2022, 15(8), 2854; https://doi.org/10.3390/ma15082854 - 13 Apr 2022
Cited by 27 | Viewed by 4806
Abstract
The application of light-emitting diodes (LEDs) has been gaining popularity over the last decades. LEDs have advantages compared to traditional light sources in terms of lifecycle, robustness, compactness, flexibility, and the absence of non-hazardous material. Combining these advantages with the possibility of emitting [...] Read more.
The application of light-emitting diodes (LEDs) has been gaining popularity over the last decades. LEDs have advantages compared to traditional light sources in terms of lifecycle, robustness, compactness, flexibility, and the absence of non-hazardous material. Combining these advantages with the possibility of emitting Ultraviolet C (UVC) makes LEDs serious candidates for light sources in decontamination systems. Nevertheless, it is unclear if they present better decontamination effectiveness than traditional mercury vapor lamps. Hence, this research uses a systematic literature review (SLR) to enlighten three aspects: (1) UVC LEDs’ application according to the field, (2) UVC LEDs’ application in terms of different biological indicators, and (3) the decontamination effectiveness of UVC LEDs in comparison to conventional lamps. UVC LEDs have spread across multiple areas, ranging from health applications to wastewater or food decontamination. The UVC LEDs’ decontamination effectiveness is as good as mercury vapor lamps. In some cases, LEDs even provide better results than conventional mercury vapor lamps. However, the increase in the targets’ complexity (e.g., multilayers or thicker individual layers) may reduce the UVC decontamination efficacy. Therefore, UVC LEDs still require considerable optimization. These findings are stimulating for developing industrial or final users’ applications. Full article
(This article belongs to the Special Issue Advanced Materials for Biophotonics Applications)
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31 pages, 3624 KiB  
Review
Electrical Resistivity Measurements for Nondestructive Evaluation of Chloride-Induced Deterioration of Reinforced Concrete—A Review
by Kevin Paolo V. Robles, Jurng-Jae Yee and Seong-Hoon Kee
Materials 2022, 15(8), 2725; https://doi.org/10.3390/ma15082725 - 7 Apr 2022
Cited by 38 | Viewed by 6464
Abstract
The objective of this study is to review, evaluate, and compare the existing research and practices on electrical resistivity as a nondestructive technique in evaluating chloride-induced deterioration of reinforced concrete elements in buildings and civil infrastructure systems. First, this paper summarizes the different [...] Read more.
The objective of this study is to review, evaluate, and compare the existing research and practices on electrical resistivity as a nondestructive technique in evaluating chloride-induced deterioration of reinforced concrete elements in buildings and civil infrastructure systems. First, this paper summarizes the different measurement techniques for gathering electrical resistivity (ER) values on concrete. Second, comparison analyses are performed to review the correlation of ER to different parameters representing corrosive environment and activity of steel corrosion in concrete, such as degree of water saturation, chloride penetration and diffusivity, and corrosion rate. In addition, this research enumerates and individually discusses the different environmental and interference factors that are not related to the electrochemical process of steel corrosion in concrete but directly affect the ER measurements, including temperature, the presence of steel reinforcement, cracks and delamination defects, specimen geometry, and concrete composition. Lastly and most importantly, discussions are made to determine the current gap of knowledge, to improve the utilization of this method in field and laboratory measurements, and future research. Full article
(This article belongs to the Section Construction and Building Materials)
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34 pages, 6077 KiB  
Review
Magnetite Nanoparticles: Synthesis and Applications in Optics and Nanophotonics
by Nataliia Dudchenko, Shweta Pawar, Ilana Perelshtein and Dror Fixler
Materials 2022, 15(7), 2601; https://doi.org/10.3390/ma15072601 - 1 Apr 2022
Cited by 67 | Viewed by 13835
Abstract
Magnetite nanoparticles with different surface coverages are of great interest for many applications due to their intrinsic magnetic properties, nanometer size, and definite surface morphology. Magnetite nanoparticles are widely used for different medical-biological applications while their usage in optics is not as widespread. [...] Read more.
Magnetite nanoparticles with different surface coverages are of great interest for many applications due to their intrinsic magnetic properties, nanometer size, and definite surface morphology. Magnetite nanoparticles are widely used for different medical-biological applications while their usage in optics is not as widespread. In recent years, nanomagnetite suspensions, so-called magnetic ferrofluids, are applied in optics due to their magneto-optical properties. This review gives an overview of nanomagnetite synthesis and its properties. In addition, the preparation and application of magnetic nanofluids in optics, nanophotonics, and magnetic imaging are described. Full article
(This article belongs to the Special Issue Feature Paper in Optical and Photonic Materials)
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28 pages, 4061 KiB  
Review
Porphyrins and Phthalocyanines on Solid-State Mesoporous Matrices as Catalysts in Oxidation Reactions
by Joanna Szymczak and Michal Kryjewski
Materials 2022, 15(7), 2532; https://doi.org/10.3390/ma15072532 - 30 Mar 2022
Cited by 25 | Viewed by 3524
Abstract
The review presents recent examples of heterogenic catalysts based on porphyrins and phthalocyanines loaded on mesoporous materials, such as MCM-41, SBA-15, MCM-48, SBA-16 or Al-MCM-41. Heterogenic approach to catalysis eases recovery, reuse and prevent macrocycle aggregation. In this application, mesoporous silica is a [...] Read more.
The review presents recent examples of heterogenic catalysts based on porphyrins and phthalocyanines loaded on mesoporous materials, such as MCM-41, SBA-15, MCM-48, SBA-16 or Al-MCM-41. Heterogenic approach to catalysis eases recovery, reuse and prevent macrocycle aggregation. In this application, mesoporous silica is a promising candidate for anchoring macrocycle and obtaining a new catalyst. Introduction of porphyrin or phthalocyanine into the mesoporous material may be performed through adsorption of the macrocycle, or by its in situ formation—by reaction of substrates introduced to the pores of the catalytic material. Catalytic reactions studied are oxidation processes, focused on alkane, alkene or arene as substrates. The products obtained are usually epoxides, alcohols, ketones, aldehydes or acids. The greatest interest lies in oxidation of cyclohexane and cyclohexene, as a source of adypic acid and derivatives. Some of the reactions may be viewed as biomimetic processes, resembling processes that occur in vivo and are catalyzed by cytochrome P450 enzyme family. Full article
(This article belongs to the Special Issue Solid State-Supported Porphyrins and Phthalocyanines as Catalysts and Photocatalysts)
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Graphical abstract

26 pages, 3011 KiB  
Review
Effects of Shot Peening and Cavitation Peening on Properties of Surface Layer of Metallic Materials—A Short Review
by Aleksander Świetlicki, Mirosław Szala and Mariusz Walczak
Materials 2022, 15(7), 2476; https://doi.org/10.3390/ma15072476 - 27 Mar 2022
Cited by 38 | Viewed by 6491
Abstract
Shot peening is a dynamically developing surface treatment used to improve the surface properties modified by tool, impact, microblasting, or shot action. This paper reviews the basic information regarding shot peening methods. The peening processes and effects of the shot peening and cavitation [...] Read more.
Shot peening is a dynamically developing surface treatment used to improve the surface properties modified by tool, impact, microblasting, or shot action. This paper reviews the basic information regarding shot peening methods. The peening processes and effects of the shot peening and cavitation peening treatments on the surface layer properties of metallic components are analysed. Moreover, the effects of peening on the operational performance of metallic materials are summarized. Shot peening is generally applied to reduce the surface roughness, increase the hardness, and densify the surface layer microstructure, which leads to work hardening effects. In addition, the residual compressive stresses introduced into the material have a beneficial effect on the performance of the surface layer. Therefore, peening can be beneficial for metallic structures prone to fatigue, corrosion, and wear. Recently, cavitation peening has been increasingly developed. This review paper suggests that most research on cavitation peening omits the treatment of additively manufactured metallic materials. Furthermore, no published studies combine shot peening and cavitation peening in one hybrid process, which could synthesize the benefits of both peening processes. Moreover, there is a need to investigate the effects of peening, especially cavitation peening and hybrid peening, on the anti-wear and corrosion performance of additively manufactured metallic materials. Therefore, the literature gap leading to the scope of future work is also included. Full article
(This article belongs to the Special Issue Metallic and Ceramic Materials Integrity – Surface Engineering for Wear, Corrosion and Erosion Prevention)
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18 pages, 6243 KiB  
Review
Metal Marking Behavior and Testing of Porcelain Tableware
by Luc Hennetier, Ana Moura and Manuel Ribeiro
Materials 2022, 15(7), 2442; https://doi.org/10.3390/ma15072442 - 25 Mar 2022
Cited by 2 | Viewed by 3488
Abstract
The term “metal marking” is widely used to define the common phenomenon of tableware glazes being damaged by metallic cutlery. Appearing as unaesthetic gray marks and scratches resulting from normal conditions of use, these defects deeply affect the performance of ceramic products, especially [...] Read more.
The term “metal marking” is widely used to define the common phenomenon of tableware glazes being damaged by metallic cutlery. Appearing as unaesthetic gray marks and scratches resulting from normal conditions of use, these defects deeply affect the performance of ceramic products, especially in intensive environments, such as in the hospitality industry. The scope of this article is to establish a comprehensive review of the phenomenon, focusing on the physical and chemical mechanisms involved in the process, and their interactions and consequences. It also intends to list the different methods normally followed to avoid or at least reduce this defect, in order to enhance the durability of porcelain dishware. This manuscript also provides a review of the different testing methods developed and used by the tableware industry and technical centers to quantify the ability of porcelain tableware to produce metal marks. To face the current lack of any international or at least national standard testing procedure that would permit a reliable comparison of products, a new metal marking test developed at the Technological Center for Ceramic and Glass (CTCV) is presented as an alternative to common tests normally based on knives as a marking tool. Full article
(This article belongs to the Special Issue Science and Technology of Porcelain: History, Processing, Structure and Properties)
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18 pages, 5022 KiB  
Review
Programming Soft Shape-Morphing Systems by Harnessing Strain Mismatch and Snap-Through Bistability: A Review
by Yi Wu, Gang Guo, Zhuxuan Wei and Jin Qian
Materials 2022, 15(7), 2397; https://doi.org/10.3390/ma15072397 - 24 Mar 2022
Cited by 10 | Viewed by 4539
Abstract
Multi-modal and controllable shape-morphing constitutes the cornerstone of the functionalization of soft actuators/robots. Involving heterogeneity through material layout is a widely used strategy to generate internal mismatches in active morphing structures. Once triggered by external stimuli, the entire structure undergoes cooperative deformation by [...] Read more.
Multi-modal and controllable shape-morphing constitutes the cornerstone of the functionalization of soft actuators/robots. Involving heterogeneity through material layout is a widely used strategy to generate internal mismatches in active morphing structures. Once triggered by external stimuli, the entire structure undergoes cooperative deformation by minimizing the potential energy. However, the intrinsic limitation of soft materials emerges when it comes to applications such as soft actuators or load-bearing structures that require fast response and large output force. Many researchers have explored the use of the structural principle of snap-through bistability as the morphing mechanisms. Bistable or multi-stable mechanical systems possess more than one local energy minimum and are capable of resting in any of these equilibrium states without external forces. The snap-through motion could overcome energy barriers to switch among these stable or metastable states with dramatically distinct geometries. Attributed to the energy storage and release mechanism, such snap-through transition is quite highly efficient, accompanied by fast response speed, large displacement magnitude, high manipulation strength, and moderate driving force. For example, the shape-morphing timescale of conventional hydrogel systems is usually tens of minutes, while the activation time of hydrogel actuators using the elastic snapping instability strategy can be reduced to below 1 s. By rationally embedding stimuli-responsive inclusions to offer the required trigger energy, various controllable snap-through actuations could be achieved. This review summarizes the current shape-morphing programming strategies based on mismatch strain induced by material heterogeneity, with emphasis on how to leverage snap-through bistability to broaden the applications of the shape-morphing structures in soft robotics and mechanical metamaterials. Full article
(This article belongs to the Special Issue Mechanical Metamaterials: Optimization and New Design Ideas)
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37 pages, 23480 KiB  
Review
Engineering 2D Materials for Photocatalytic Water-Splitting from a Theoretical Perspective
by Mukesh Jakhar, Ashok Kumar, Pradeep K. Ahluwalia, Kumar Tankeshwar and Ravindra Pandey
Materials 2022, 15(6), 2221; https://doi.org/10.3390/ma15062221 - 17 Mar 2022
Cited by 67 | Viewed by 6588
Abstract
Splitting of water with the help of photocatalysts has gained a strong interest in the scientific community for producing clean energy, thus requiring novel semiconductor materials to achieve high-yield hydrogen production. The emergence of 2D nanoscale materials with remarkable electronic and optical properties [...] Read more.
Splitting of water with the help of photocatalysts has gained a strong interest in the scientific community for producing clean energy, thus requiring novel semiconductor materials to achieve high-yield hydrogen production. The emergence of 2D nanoscale materials with remarkable electronic and optical properties has received much attention in this field. Owing to the recent developments in high-end computation and advanced electronic structure theories, first principles studies offer powerful tools to screen photocatalytic systems reliably and efficiently. This review is organized to highlight the essential properties of 2D photocatalysts and the recent advances in the theoretical engineering of 2D materials for the improvement in photocatalytic overall water-splitting. The advancement in the strategies including (i) single-atom catalysts, (ii) defect engineering, (iii) strain engineering, (iv) Janus structures, (v) type-II heterostructures (vi) Z-scheme heterostructures (vii) multilayer configurations (viii) edge-modification in nanoribbons and (ix) the effect of pH in overall water-splitting are summarized to improve the existing problems for a photocatalytic catalytic reaction such as overcoming large overpotential to trigger the water-splitting reactions without using cocatalysts. This review could serve as a bridge between theoretical and experimental research on next-generation 2D photocatalysts. Full article
(This article belongs to the Special Issue Electronic Structure Theory of Low Dimensional Materials)
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31 pages, 4478 KiB  
Review
Exploring the Journey of Zinc Oxide Nanoparticles (ZnO-NPs) toward Biomedical Applications
by Fahadul Islam, Sheikh Shohag, Md. Jalal Uddin, Md. Rezaul Islam, Mohamed H. Nafady, Aklima Akter, Saikat Mitra, Arpita Roy, Talha Bin Emran and Simona Cavalu
Materials 2022, 15(6), 2160; https://doi.org/10.3390/ma15062160 - 15 Mar 2022
Cited by 240 | Viewed by 12794
Abstract
The field of nanotechnology is concerned with the creation and application of materials having a nanoscale spatial dimensioning. Having a considerable surface area to volume ratio, nanoparticles have particularly unique properties. Several chemical and physical strategies have been used to prepare zinc oxide [...] Read more.
The field of nanotechnology is concerned with the creation and application of materials having a nanoscale spatial dimensioning. Having a considerable surface area to volume ratio, nanoparticles have particularly unique properties. Several chemical and physical strategies have been used to prepare zinc oxide nanoparticles (ZnO-NPs). Still, biological methods using green or natural routes in various underlying substances (e.g., plant extracts, enzymes, and microorganisms) can be more environmentally friendly and cost-effective than chemical and/or physical methods in the long run. ZnO-NPs are now being studied as antibacterial agents in nanoscale and microscale formulations. The purpose of this study is to analyze the prevalent traditional method of generating ZnO-NPs, as well as its harmful side effects, and how it might be addressed utilizing an eco-friendly green approach. The study’s primary focus is on the potential biomedical applications of green synthesized ZnO-NPs. Biocompatibility and biomedical qualities have been improved in green-synthesized ZnO-NPs over their traditionally produced counterparts, making them excellent antibacterial and cancer-fighting drugs. Additionally, these ZnO-NPs are beneficial when combined with the healing processes of wounds and biosensing components to trace small portions of biomarkers linked with various disorders. It has also been discovered that ZnO-NPs can distribute and sense drugs. Green-synthesized ZnO-NPs are compared to traditionally synthesized ones in this review, which shows that they have outstanding potential as a potent biological agent, as well as related hazardous properties. Full article
(This article belongs to the Special Issue Preparation, Physico-Chemical Properties and Biomedical Applications of Nanoparticles)
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20 pages, 2045 KiB  
Review
Achievements and Future Perspectives of the Trivalent Thulium-Ion-Doped Mixed-Sesquioxide Ceramics for Laser Applications
by Angela Pirri, Roman N. Maksimov, Jiang Li, Matteo Vannini and Guido Toci
Materials 2022, 15(6), 2084; https://doi.org/10.3390/ma15062084 - 11 Mar 2022
Cited by 28 | Viewed by 3286
Abstract
This paper is devoted to reviewing the latest results achieved in solid-state lasers based on thulium-doped mixed-sesquioxide ceramics, i.e., (Lu,Sc,Y)2O3. The near- and mid-infrared regions are of interest for many applications, from medicine to remote sensing, as they match [...] Read more.
This paper is devoted to reviewing the latest results achieved in solid-state lasers based on thulium-doped mixed-sesquioxide ceramics, i.e., (Lu,Sc,Y)2O3. The near- and mid-infrared regions are of interest for many applications, from medicine to remote sensing, as they match molecular fingerprints and cover several atmospheric transparency windows. These matrices are characterized by a strong electron–phonon interaction—which results in a large splitting of the ground state—and by a spectral broadening of the optical transition suitable for developing tunable and short-pulse lasers. In particular, the manuscript reports on the trivalent thulium laser transitions at 1.5, 1.9, and 2.3 µm, along with the thermal and optical characteristics of the (Lu,Sc,Y)2O3 ceramics, including the fabrication techniques, spectroscopic and optical properties, and laser performances achieved in different pumping regimes, such as continuous-wave (CW), quasi-CW, and pulsed modes. A comparison of the performance obtained with these mixed-sesquioxide ceramics and with the corresponding crystals is reported. Full article
(This article belongs to the Special Issue Multiple Applications for Ceramic Materials)
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29 pages, 4254 KiB  
Review
Current Research and Challenges in Bitumen Emulsion Manufacturing and Its Properties
by Ahmed Al-Mohammedawi and Konrad Mollenhauer
Materials 2022, 15(6), 2026; https://doi.org/10.3390/ma15062026 - 9 Mar 2022
Cited by 19 | Viewed by 9135
Abstract
The global increase of road infrastructure and its impact on the environment requires serious attention to develop sustainable and environmentally friendly road materials. One group of those materials is produced by using bitumen emulsion. However, there are still scientific and technical obstacles standing [...] Read more.
The global increase of road infrastructure and its impact on the environment requires serious attention to develop sustainable and environmentally friendly road materials. One group of those materials is produced by using bitumen emulsion. However, there are still scientific and technical obstacles standing against its regular application. The bitumen emulsion formulation process and compositional optimization are subjected to a high number of degrees of freedom. Consequently, obtaining the desired product is mostly based on a series of random and tedious trials because of the enormous number of tests that are carried out to meet the required properties, such as emulsion stability, viscosity, droplet size (and distribution), and bitumen emulsion chemistry. Several pre-established formulation procedures have been presented in the literature. Some of them have technical limitations to be utilized for practical industrial application, whereas others are still not understood enough to be applied in bitumen emulsion formulation. Therefore, discussing some important issues in this field could be useful to offer a practical guide for bitumen emulsion manufacturers when trying to formulate a well-defined bitumen emulsion to best fit its use in pavement infrastructure rather than to simply to meet standard specifications. This review paper aims to enable the ultimate potential of bitumen emulsion by further reviewing the research progress of bitumen emulsion manufacturing and discussing the literature available up to now on this topic, in the realm of bitumen emulsion manufacturing and emulsion chemistry. Full article
(This article belongs to the Special Issue Feature Papers in Construction and Building Materials)
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19 pages, 4390 KiB  
Review
Production and Upgrading of Recovered Carbon Black from the Pyrolysis of End-of-Life Tires
by Sebastião M. R. Costa, David Fowler, Germano A. Carreira, Inês Portugal and Carlos M. Silva
Materials 2022, 15(6), 2030; https://doi.org/10.3390/ma15062030 - 9 Mar 2022
Cited by 40 | Viewed by 9961
Abstract
Increasing awareness regarding fossil fuel dependence, waste valorization, and greenhouse gas emissions have prompted the emergence of new solutions for numerous markets over the last decades. The tire industry is no exception to this, with a global production of more than 1.5 billion [...] Read more.
Increasing awareness regarding fossil fuel dependence, waste valorization, and greenhouse gas emissions have prompted the emergence of new solutions for numerous markets over the last decades. The tire industry is no exception to this, with a global production of more than 1.5 billion tires per year raising environmental concerns about their end-of-life recycling or disposal. Pyrolysis enables the recovery of both energy and material from end-of-life tires, yielding valuable gas, liquid, and solid fractions. The latter, known as recovered carbon black (rCB), has been extensively researched in the last few years to ensure its quality for market applications. These studies have shown that rCB quality depends on the feedstock composition and pyrolysis conditions such as type of reactor, temperature range, heating rate, and residence time. Recent developments of activation and demineralization techniques target the production of rCB with specific chemical, physical, and morphological properties for singular applications. The automotive industry, which is the highest consumer of carbon black, has set specific targets to incorporate recycled materials (such as rCB) following the principles of sustainability and a circular economy. This review summarizes the pyrolysis of end-of-life tires for the production of syngas, oil, and rCB, focusing on the process conditions and product yield and composition. A further analysis of the characteristics of the solid material is performed, including their influence on the rCB application as a substitute of commercial CB in the tire industry. Purification and modification post-treatment processes for rCB upgrading are also inspected. Full article
(This article belongs to the Special Issue Advance in Environmentally Friendly Materials)
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11 pages, 5081 KiB  
Review
Eu3+ as a Powerful Structural and Spectroscopic Tool for Glass Photonics
by Thi Ngoc Lam Tran, Alessandro Chiasera, Anna Lukowiak and Maurizio Ferrari
Materials 2022, 15(5), 1847; https://doi.org/10.3390/ma15051847 - 1 Mar 2022
Cited by 13 | Viewed by 2741
Abstract
The unique properties of the Eu3+ ion make it a powerful spectroscopic tool to investigate structure or follow processes and mechanisms in several high-tech application areas such as biology and health, structural engineering, environment monitoring systems and quantum technology, mainly concerning photonics. [...] Read more.
The unique properties of the Eu3+ ion make it a powerful spectroscopic tool to investigate structure or follow processes and mechanisms in several high-tech application areas such as biology and health, structural engineering, environment monitoring systems and quantum technology, mainly concerning photonics. The traditional method is to exploit the unique photoluminescent properties of Eu3+ ions to understand complex dynamical processes and obtain information useful to develop materials with specific characteristics. The objective of this review is to focus on the use of Eu3+ optical spectroscopy in some condensed matter issues. After a short presentation of the more significant properties of the Eu3+ ion, some examples regarding its use as a probe of the local structure in sol–gel systems are presented. Another section is devoted to dynamical processes such as the important technological role of nanocrystals as rare-earth sensitizers. The appealing effect of the site-selection memory, observed when exciting different sites into the 5D1 state, which the 5D0 → 7F0 emission band reflects following the sites’ distribution, is also mentioned. Finally, a section is devoted to the use of Eu3+ in the development of a rare-earth-based platform for quantum technologies. Full article
(This article belongs to the Special Issue Structural and Optical Studies of Eu3+ Doped Materials)
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23 pages, 6668 KiB  
Review
MXene (Ti3C2Tx)-Embedded Nanocomposite Hydrogels for Biomedical Applications: A Review
by Fouad Damiri, Md. Habibur Rahman, Mehrukh Zehravi, Aeshah A. Awaji, Mohammed Z. Nasrullah, Heba A. Gad, Mutasem Z. Bani-Fwaz, Rajender S. Varma, Mousa O. Germoush, Hamdan S. Al-malky, Amany A. Sayed, Satish Rojekar, Mohamed M. Abdel-Daim and Mohammed Berrada
Materials 2022, 15(5), 1666; https://doi.org/10.3390/ma15051666 - 23 Feb 2022
Cited by 59 | Viewed by 7553
Abstract
Polymeric nanocomposites have been outstanding functional materials and have garnered immense attention as sustainable materials to address multi-disciplinary problems. MXenes have emerged as a newer class of 2D materials that produce metallic conductivity upon interaction with hydrophilic species, and their delamination affords monolayer [...] Read more.
Polymeric nanocomposites have been outstanding functional materials and have garnered immense attention as sustainable materials to address multi-disciplinary problems. MXenes have emerged as a newer class of 2D materials that produce metallic conductivity upon interaction with hydrophilic species, and their delamination affords monolayer nanoplatelets of a thickness of about one nm and a side size in the micrometer range. Delaminated MXene has a high aspect ratio, making it an alluring nanofiller for multifunctional polymer nanocomposites. Herein, we have classified and discussed the structure, properties and application of major polysaccharide-based electroactive hydrogels (hyaluronic acid (HA), alginate sodium (SA), chitosan (CS) and cellulose) in biomedical applications, starting with the brief historical account of MXene’s development followed by successive discussions on the synthesis methods, structures and properties of nanocomposites encompassing polysaccharides and MXenes, including their biomedical applications, cytotoxicity and biocompatibility aspects. Finally, the MXenes and their utility in the biomedical arena is deliberated with an eye on potential opportunities and challenges anticipated for them in the future, thus promoting their multifaceted applications. Full article
(This article belongs to the Special Issue MXenes and Their Composites for Emerging Applications)
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15 pages, 4882 KiB  
Review
Progress and Challenges of InGaN/GaN-Based Core–Shell Microrod LEDs
by Johanna Meier and Gerd Bacher
Materials 2022, 15(5), 1626; https://doi.org/10.3390/ma15051626 - 22 Feb 2022
Cited by 15 | Viewed by 3760
Abstract
LEDs based on planar InGaN/GaN heterostructures define an important standard for solid-state lighting. However, one drawback is the polarization field of the wurtzite heterostructure impacting both electron–hole overlap and emission energy. Three-dimensional core–shell microrods offer field-free sidewalls, thus improving radiative recombination rates while [...] Read more.
LEDs based on planar InGaN/GaN heterostructures define an important standard for solid-state lighting. However, one drawback is the polarization field of the wurtzite heterostructure impacting both electron–hole overlap and emission energy. Three-dimensional core–shell microrods offer field-free sidewalls, thus improving radiative recombination rates while simultaneously increasing the light-emitting area per substrate size. Despite those promises, microrods have still not replaced planar devices. In this review, we discuss the progress in device processing and analysis of microrod LEDs and emphasize the perspectives related to the 3D device architecture from an applications point of view. Full article
(This article belongs to the Special Issue Optoelectronic Devices: 2021)
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39 pages, 72409 KiB  
Review
Photothermal and Photodynamic Therapy of Tumors with Plasmonic Nanoparticles: Challenges and Prospects
by Alla B. Bucharskaya, Nikolai G. Khlebtsov, Boris N. Khlebtsov, Galina N. Maslyakova, Nikita A. Navolokin, Vadim D. Genin, Elina A. Genina and Valery V. Tuchin
Materials 2022, 15(4), 1606; https://doi.org/10.3390/ma15041606 - 21 Feb 2022
Cited by 48 | Viewed by 6665
Abstract
Cancer remains one of the leading causes of death in the world. For a number of neoplasms, the efficiency of conventional chemo- and radiation therapies is insufficient because of drug resistance and marked toxicity. Plasmonic photothermal therapy (PPT) using local hyperthermia induced by [...] Read more.
Cancer remains one of the leading causes of death in the world. For a number of neoplasms, the efficiency of conventional chemo- and radiation therapies is insufficient because of drug resistance and marked toxicity. Plasmonic photothermal therapy (PPT) using local hyperthermia induced by gold nanoparticles (AuNPs) has recently been extensively explored in tumor treatment. However, despite attractive promises, the current PPT status is limited by laboratory experiments, academic papers, and only a few preclinical studies. Unfortunately, most nanoformulations still share a similar fate: great laboratory promises and fair preclinical trials. This review discusses the current challenges and prospects of plasmonic nanomedicine based on PPT and photodynamic therapy (PDT). We start with consideration of the fundamental principles underlying plasmonic properties of AuNPs to tune their plasmon resonance for the desired NIR-I, NIR-2, and SWIR optical windows. The basic principles for simulation of optical cross-sections and plasmonic heating under CW and pulsed irradiation are discussed. Then, we consider the state-of-the-art methods for wet chemical synthesis of the most popular PPPT AuNPs such as silica/gold nanoshells, Au nanostars, nanorods, and nanocages. The photothermal efficiencies of these nanoparticles are compared, and their applications to current nanomedicine are shortly discussed. In a separate section, we discuss the fabrication of gold and other nanoparticles by the pulsed laser ablation in liquid method. The second part of the review is devoted to our recent experimental results on laser-activated interaction of AuNPs with tumor and healthy tissues and current achievements of other research groups in this application area. The unresolved issues of PPT are the significant accumulation of AuNPs in the organs of the mononuclear phagocyte system, causing potential toxic effects of nanoparticles, and the possibility of tumor recurrence due to the presence of survived tumor cells. The prospective ways of solving these problems are discussed, including developing combined antitumor therapy based on combined PPT and PDT. In the conclusion section, we summarize the most urgent needs of current PPT-based nanomedicine. Full article
(This article belongs to the Special Issue Feature Paper in Optical and Photonic Materials)
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26 pages, 14735 KiB  
Review
Carbon Nanotube Devices for Quantum Technology
by Andrey Baydin, Fuyang Tay, Jichao Fan, Manukumara Manjappa, Weilu Gao and Junichiro Kono
Materials 2022, 15(4), 1535; https://doi.org/10.3390/ma15041535 - 18 Feb 2022
Cited by 44 | Viewed by 9518
Abstract
Carbon nanotubes, quintessentially one-dimensional quantum objects, possess a variety of electrical, optical, and mechanical properties that are suited for developing devices that operate on quantum mechanical principles. The states of one-dimensional electrons, excitons, and phonons in carbon nanotubes with exceptionally large quantization energies [...] Read more.
Carbon nanotubes, quintessentially one-dimensional quantum objects, possess a variety of electrical, optical, and mechanical properties that are suited for developing devices that operate on quantum mechanical principles. The states of one-dimensional electrons, excitons, and phonons in carbon nanotubes with exceptionally large quantization energies are promising for high-operating-temperature quantum devices. Here, we discuss recent progress in the development of carbon-nanotube-based devices for quantum technology, i.e., quantum mechanical strategies for revolutionizing computation, sensing, and communication. We cover fundamental properties of carbon nanotubes, their growth and purification methods, and methodologies for assembling them into architectures of ordered nanotubes that manifest macroscopic quantum properties. Most importantly, recent developments and proposals for quantum information processing devices based on individual and assembled nanotubes are reviewed. Full article
(This article belongs to the Special Issue Materials Opportunities and Challenges for Quantum Information Processors)
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33 pages, 7644 KiB  
Review
Application of Graphene-Related Materials in Organic Solar Cells
by Lara Velasco Davoise, Ana M. Díez-Pascual and Rafael Peña Capilla
Materials 2022, 15(3), 1171; https://doi.org/10.3390/ma15031171 - 3 Feb 2022
Cited by 32 | Viewed by 5139
Abstract
Graphene-related materials (GRMs) such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoribbons (GNRs), and so forth have recently emerged as photovoltaic (PV) materials due to their nanodimensional structure and outstanding properties such as high electrical and thermal [...] Read more.
Graphene-related materials (GRMs) such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoribbons (GNRs), and so forth have recently emerged as photovoltaic (PV) materials due to their nanodimensional structure and outstanding properties such as high electrical and thermal conductivity, large specific surface, and unique combination of mechanical strength and flexibility. They can be a crucial part of transparent electrodes, hole/electron transport materials, and active layers in organic solar cells (OSCs). Besides their role in charge extraction and transport, GRMs act as device protectors against environmental degradation through their compact bidimensional structure and offer good durability. This review briefly presents the synthesis methods of GRMs and describes the current progress in GRM-based OSCs. PV parameters (short circuit current, open circuit voltage, power conversion efficiency, and fill factor) are summarized and comparatively discussed for the different structures. The efficiency recently surpassed 15% for an OSC incorporating polymer-modified graphene as a transparent electrode. The long-term stability of OSCs incorporating GRMs is also discussed. Finally, conclusions and the outlook for future investigation into GRM-based devices for PVs are presented. Full article
(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)
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26 pages, 8120 KiB  
Review
Ga2O3 and Related Ultra-Wide Bandgap Power Semiconductor Oxides: New Energy Electronics Solutions for CO2 Emission Mitigation
by Zeyu Chi, Jacob J. Asher, Michael R. Jennings, Ekaterine Chikoidze and Amador Pérez-Tomás
Materials 2022, 15(3), 1164; https://doi.org/10.3390/ma15031164 - 2 Feb 2022
Cited by 47 | Viewed by 9236
Abstract
Currently, a significant portion (~50%) of global warming emissions, such as CO2, are related to energy production and transportation. As most energy usage will be electrical (as well as transportation), the efficient management of electrical power is thus central to achieve [...] Read more.
Currently, a significant portion (~50%) of global warming emissions, such as CO2, are related to energy production and transportation. As most energy usage will be electrical (as well as transportation), the efficient management of electrical power is thus central to achieve the XXI century climatic goals. Ultra-wide bandgap (UWBG) semiconductors are at the very frontier of electronics for energy management or energy electronics. A new generation of UWBG semiconductors will open new territories for higher power rated power electronics and solar-blind deeper ultraviolet optoelectronics. Gallium oxide—Ga2O3 (4.5–4.9 eV), has recently emerged pushing the limits set by more conventional WBG (~3 eV) materials, such as SiC and GaN, as well as for transparent conducting oxides (TCO), such asIn2O3, ZnO and SnO2, to name a few. Indeed, Ga2O3 as the first oxide used as a semiconductor for power electronics, has sparked an interest in oxide semiconductors to be investigated (oxides represent the largest family of UWBG). Among these new power electronic materials, AlxGa1-xO3 may provide high-power heterostructure electronic and photonic devices at bandgaps far beyond all materials available today (~8 eV) or ZnGa2O4 (~5 eV), enabling spinel bipolar energy electronics for the first time ever. Here, we review the state-of-the-art and prospects of some ultra-wide bandgap oxide semiconductor arising technologies as promising innovative material solutions towards a sustainable zero emission society. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section)
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33 pages, 37468 KiB  
Review
Photocatalytic Reduction of Carbon Dioxide on TiO2 Heterojunction Photocatalysts—A Review
by Beatriz Trindade Barrocas, Nela Ambrožová and Kamila Kočí
Materials 2022, 15(3), 967; https://doi.org/10.3390/ma15030967 - 26 Jan 2022
Cited by 43 | Viewed by 9942
Abstract
The photocatalytic reduction of carbon dioxide to renewable fuel or other valuable chemicals using solar energy is attracting the interest of researchers because of its great potential to offer a clean fuel alternative and solve global warming problems. Unfortunately, the efficiency of CO [...] Read more.
The photocatalytic reduction of carbon dioxide to renewable fuel or other valuable chemicals using solar energy is attracting the interest of researchers because of its great potential to offer a clean fuel alternative and solve global warming problems. Unfortunately, the efficiency of CO2 photocatalytic reduction remains not very high due to the fast recombination of photogenerated electron–hole and small light utilization. Consequently, tremendous efforts have been made to solve these problems, and one possible solution is the use of heterojunction photocatalysts. This review begins with the fundamental aspects of CO2 photocatalytic reduction and the fundamental principles of various heterojunction photocatalysts. In the following part, we discuss using TiO2 heterojunction photocatalysts with other semiconductors, such as C3N4, CeO2, CuO, CdS, MoS2, GaP, CaTiO3 and FeTiO3. Finally, a concise summary and presentation of perspectives in the field of heterojunction photocatalysts are provided. The review covers references in the years 2011–2021. Full article
(This article belongs to the Special Issue Advanced Oxide-Based Materials for Photocatalytic Applications)
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29 pages, 4052 KiB  
Review
Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices
by Raffaella Lo Nigro, Patrick Fiorenza, Giuseppe Greco, Emanuela Schilirò and Fabrizio Roccaforte
Materials 2022, 15(3), 830; https://doi.org/10.3390/ma15030830 - 22 Jan 2022
Cited by 23 | Viewed by 6604
Abstract
High-κ dielectrics are insulating materials with higher permittivity than silicon dioxide. These materials have already found application in microelectronics, mainly as gate insulators or passivating layers for silicon (Si) technology. However, since the last decade, the post-Si era began with the pervasive introduction [...] Read more.
High-κ dielectrics are insulating materials with higher permittivity than silicon dioxide. These materials have already found application in microelectronics, mainly as gate insulators or passivating layers for silicon (Si) technology. However, since the last decade, the post-Si era began with the pervasive introduction of wide band gap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), which opened new perspectives for high-κ materials in these emerging technologies. In this context, aluminium and hafnium oxides (i.e., Al2O3, HfO2) and some rare earth oxides (e.g., CeO2, Gd2O3, Sc2O3) are promising high-κ binary oxides that can find application as gate dielectric layers in the next generation of high-power and high-frequency transistors based on SiC and GaN. This review paper gives a general overview of high-permittivity binary oxides thin films for post-Si electronic devices. In particular, focus is placed on high-κ binary oxides grown by atomic layer deposition on WBG semiconductors (silicon carbide and gallium nitride), as either amorphous or crystalline films. The impacts of deposition modes and pre- or postdeposition treatments are both discussed. Moreover, the dielectric behaviour of these films is also presented, and some examples of high-κ binary oxides applied to SiC and GaN transistors are reported. The potential advantages and the current limitations of these technologies are highlighted. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section)
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15 pages, 1700 KiB  
Review
Recent Advances in Materials and Flexible Sensors for Arrhythmia Detection
by Matthew Guess, Nathan Zavanelli and Woon-Hong Yeo
Materials 2022, 15(3), 724; https://doi.org/10.3390/ma15030724 - 18 Jan 2022
Cited by 21 | Viewed by 5177
Abstract
Arrhythmias are one of the leading causes of death in the United States, and their early detection is essential for patient wellness. However, traditional arrhythmia diagnosis by expert evaluation from intermittent clinical examinations is time-consuming and often lacks quantitative data. Modern wearable sensors [...] Read more.
Arrhythmias are one of the leading causes of death in the United States, and their early detection is essential for patient wellness. However, traditional arrhythmia diagnosis by expert evaluation from intermittent clinical examinations is time-consuming and often lacks quantitative data. Modern wearable sensors and machine learning algorithms have attempted to alleviate this problem by providing continuous monitoring and real-time arrhythmia detection. However, current devices are still largely limited by the fundamental mismatch between skin and sensor, giving way to motion artifacts. Additionally, the desirable qualities of flexibility, robustness, breathability, adhesiveness, stretchability, and durability cannot all be met at once. Flexible sensors have improved upon the current clinical arrhythmia detection methods by following the topography of skin and reducing the natural interface mismatch between cardiac monitoring sensors and human skin. Flexible bioelectric, optoelectronic, ultrasonic, and mechanoelectrical sensors have been demonstrated to provide essential information about heart-rate variability, which is crucial in detecting and classifying arrhythmias. In this review, we analyze the current trends in flexible wearable sensors for cardiac monitoring and the efficacy of these devices for arrhythmia detection. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section)
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47 pages, 20844 KiB  
Review
Multifunctional Iron Oxide Magnetic Nanoparticles for Biomedical Applications: A Review
by Hung-Vu Tran, Nhat M. Ngo, Riddhiman Medhi, Pannaree Srinoi, Tingting Liu, Supparesk Rittikulsittichai and T. Randall Lee
Materials 2022, 15(2), 503; https://doi.org/10.3390/ma15020503 - 10 Jan 2022
Cited by 100 | Viewed by 13035
Abstract
Due to their good magnetic properties, excellent biocompatibility, and low price, magnetic iron oxide nanoparticles (IONPs) are the most commonly used magnetic nanomaterials and have been extensively explored in biomedical applications. Although magnetic IONPs can be used for a variety of applications in [...] Read more.
Due to their good magnetic properties, excellent biocompatibility, and low price, magnetic iron oxide nanoparticles (IONPs) are the most commonly used magnetic nanomaterials and have been extensively explored in biomedical applications. Although magnetic IONPs can be used for a variety of applications in biomedicine, most practical applications require IONP-based platforms that can perform several tasks in parallel. Thus, appropriate engineering and integration of magnetic IONPs with different classes of organic and inorganic materials can produce multifunctional nanoplatforms that can perform several functions simultaneously, allowing their application in a broad spectrum of biomedical fields. This review article summarizes the fabrication of current composite nanoplatforms based on integration of magnetic IONPs with organic dyes, biomolecules (e.g., lipids, DNAs, aptamers, and antibodies), quantum dots, noble metal NPs, and stimuli-responsive polymers. We also highlight the recent technological advances achieved from such integrated multifunctional platforms and their potential use in biomedical applications, including dual-mode imaging for biomolecule detection, targeted drug delivery, photodynamic therapy, chemotherapy, and magnetic hyperthermia therapy. Full article
(This article belongs to the Special Issue Magnetic Nanoparticle-Based Materials: Synthesis and Biomedical Applications)
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30 pages, 3469 KiB  
Review
Layer-by-Layer Deposition: A Promising Environmentally Benign Flame-Retardant Treatment for Cotton, Polyester, Polyamide and Blended Textiles
by Eva Magovac, Bojana Vončina, Igor Jordanov, Jaime C. Grunlan and Sandra Bischof
Materials 2022, 15(2), 432; https://doi.org/10.3390/ma15020432 - 7 Jan 2022
Cited by 46 | Viewed by 6085
Abstract
A detailed review of recent developments of layer-by-layer (LbL) deposition as a promising approach to reduce flammability of the most widely used fibers (cotton, polyester, polyamide and their blends) is presented. LbL deposition is an emerging green technology, showing numerous advantages over current [...] Read more.
A detailed review of recent developments of layer-by-layer (LbL) deposition as a promising approach to reduce flammability of the most widely used fibers (cotton, polyester, polyamide and their blends) is presented. LbL deposition is an emerging green technology, showing numerous advantages over current commercially available finishing processes due to the use of water as a solvent for a variety of active substances. For flame-retardant (FR) purposes, different ingredients are able to build oppositely charged layers at very low concentrations in water (e.g., small organic molecules and macromolecules from renewable sources, inorganic compounds, metallic or oxide colloids, etc.). Since the layers on a textile substrate are bonded with pH and ion-sensitive electrostatic forces, the greatest technological drawback of LbL deposition for FR finishing is its non-resistance to washing cycles. Several possibilities of laundering durability improvements by different pre-treatments, as well as post-treatments to form covalent bonds between the layers, are presented in this review. Full article
(This article belongs to the Special Issue Application of Functional Textile Materials and Films)
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46 pages, 9708 KiB  
Review
Diamond/GaN HEMTs: Where from and Where to?
by Joana C. Mendes, Michael Liehr and Changhui Li
Materials 2022, 15(2), 415; https://doi.org/10.3390/ma15020415 - 6 Jan 2022
Cited by 38 | Viewed by 10285
Abstract
Gallium nitride is a wide bandgap semiconductor material with high electric field strength and electron mobility that translate in a tremendous potential for radio-frequency communications and renewable energy generation, amongst other areas. However, due to the particular architecture of GaN high electron mobility [...] Read more.
Gallium nitride is a wide bandgap semiconductor material with high electric field strength and electron mobility that translate in a tremendous potential for radio-frequency communications and renewable energy generation, amongst other areas. However, due to the particular architecture of GaN high electron mobility transistors, the relatively low thermal conductivity of the material induces the appearance of localized hotspots that degrade the devices performance and compromise their long term reliability. On the search of effective thermal management solutions, the integration of GaN and synthetic diamond with high thermal conductivity and electric breakdown strength shows a tremendous potential. A significant effort has been made in the past few years by both academic and industrial players in the search of a technological process that allows the integration of both materials and the fabrication of high performance and high reliability hybrid devices. Different approaches have been proposed, such as the development of diamond/GaN wafers for further device fabrication or the capping of passivated GaN devices with diamond films. This paper describes in detail the potential and technical challenges of each approach and presents and discusses their advantages and disadvantages. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section)
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18 pages, 5811 KiB  
Review
Towards Perfect Absorption of Single Layer CVD Graphene in an Optical Resonant Cavity: Challenges and Experimental Achievements
by Abedin Nematpour, Maria Luisa Grilli, Laura Lancellotti and Nicola Lisi
Materials 2022, 15(1), 352; https://doi.org/10.3390/ma15010352 - 4 Jan 2022
Cited by 4 | Viewed by 3249
Abstract
Graphene is emerging as a promising material for the integration in the most common Si platform, capable to convey some of its unique properties to fabricate novel photonic and optoelectronic devices. For many real functions and devices however, graphene absorption is too low [...] Read more.
Graphene is emerging as a promising material for the integration in the most common Si platform, capable to convey some of its unique properties to fabricate novel photonic and optoelectronic devices. For many real functions and devices however, graphene absorption is too low and must be enhanced. Among strategies, the use of an optical resonant cavity was recently proposed, and graphene absorption enhancement was demonstrated, both, by theoretical and experimental studies. This paper summarizes our recent progress in graphene absorption enhancement by means of Si/SiO2-based Fabry–Perot filters fabricated by radiofrequency sputtering. Simulations and experimental achievements carried out during more than two years of investigations are reported here, detailing the technical expedients that were necessary to increase the single layer CVD graphene absorption first to 39% and then up to 84%. Graphene absorption increased when an asymmetric Fabry–Perot filter was applied rather than a symmetric one, and a further absorption increase was obtained when graphene was embedded in a reflective rather than a transmissive Fabry–Perot filter. Moreover, the effect of the incident angle of the electromagnetic radiation and of the polarization of the light was investigated in the case of the optimized reflective Fabry–Perot filter. Experimental challenges and precautions to avoid evaporation or sputtering induced damage on the graphene layers are described as well, disclosing some experimental procedures that may help other researchers to embed graphene inside PVD grown materials with minimal alterations. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section)
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30 pages, 5791 KiB  
Review
Acrylate and Methacrylate Polymers’ Applications: Second Life with Inexpensive and Sustainable Recycling Approaches
by Carmelo Corsaro, Giulia Neri, Antonio Santoro and Enza Fazio
Materials 2022, 15(1), 282; https://doi.org/10.3390/ma15010282 - 31 Dec 2021
Cited by 39 | Viewed by 6274
Abstract
Polymers are widely employed in several fields thanks to their wide versatility and the easy derivatization routes. However, a wide range of commercial polymers suffer from limited use on a large scale due to their inert nature. Nowadays, acrylate and methacrylate polymers, which [...] Read more.
Polymers are widely employed in several fields thanks to their wide versatility and the easy derivatization routes. However, a wide range of commercial polymers suffer from limited use on a large scale due to their inert nature. Nowadays, acrylate and methacrylate polymers, which are respectively derivatives of acrylic or methacrylic acid, are among the most proposed materials for their useful characteristics like good biocompatibility, capping ability toward metal clusters, low price, potentially recyclability and reusability. Here, we discuss the advantages and challenges of this class of smart polymers focusing our attention on their current technological applications in medical, electronic, food packaging and environmental remediation fields. Furthermore, we deal with the main issue of their recyclability, considering that the current commercial bioplastics are not yet able to meet the global needs as much as to totally replace fossil-fuel-based products. Finally, the most accredited strategies to reach recyclable composites based on acrylic polymers are described. Full article
(This article belongs to the Special Issue Functional Nanomaterials for a Better Life)
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25 pages, 98417 KiB  
Review
Fabrication, Structure, Performance, and Application of Graphene-Based Composite Aerogel
by Dequan Wei, Xiang Liu, Shenghua Lv, Leipeng Liu, Lei Wu, Zexiong Li and Yonggang Hou
Materials 2022, 15(1), 299; https://doi.org/10.3390/ma15010299 - 31 Dec 2021
Cited by 22 | Viewed by 5327
Abstract
Graphene-based composite aerogel (GCA) refers to a solid porous substance formed by graphene or its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), with inorganic materials and polymers. Because GCA has super-high adsorption, separation, electrical properties, and sensitivity, it has great potential [...] Read more.
Graphene-based composite aerogel (GCA) refers to a solid porous substance formed by graphene or its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), with inorganic materials and polymers. Because GCA has super-high adsorption, separation, electrical properties, and sensitivity, it has great potential for application in super-strong adsorption and separation materials, long-life fast-charging batteries, and flexible sensing materials. GCA has become a research hotspot, and many research papers and achievements have emerged in recent years. Therefore, the fabrication, structure, performance, and application prospects of GCA are summarized and discussed in this review. Meanwhile, the existing problems and development trends of GCA are also introduced so that more will know about it and be interested in researching it. Full article
(This article belongs to the Special Issue Advanced Nanocomposites Materials Based on Graphene Oxide/Reduced Graphene Oxide: Potential Applications and Perspectives)
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29 pages, 9459 KiB  
Review
Strength Characterization of Soils’ Properties at High Strain Rates Using the Hopkinson Technique—A Review of Experimental Testing
by Kamil Sobczyk, Ryszard Chmielewski, Leopold Kruszka and Ryszard Rekucki
Materials 2022, 15(1), 274; https://doi.org/10.3390/ma15010274 - 30 Dec 2021
Cited by 6 | Viewed by 3299
Abstract
The paper presents a review of crucial experiments and the latest publications, presenting the previous and current trends in experimental research in 2018–2021 in the area of soil dynamic interaction based on the Hopkinson bar technique. A review of investigated experimental test stands [...] Read more.
The paper presents a review of crucial experiments and the latest publications, presenting the previous and current trends in experimental research in 2018–2021 in the area of soil dynamic interaction based on the Hopkinson bar technique. A review of investigated experimental test stands was made, in particular, cohesive and non-cohesive soil specimens prepared with different dimensions and densities. From this study, it can be concluded that the dynamic response of the soil depends on many factors, e.g., density, cohesion, moisture and grain structure of the soil specimen. There is still a noticeable interest in SHPB experiments performed in both 1D and 3D versions under modified conditions (frozen/heated soil specimen, different degree of water saturation content of the soil sample) in a wide range of strain rates 102–104 s−1, which is a large field for further research. The need to learn about the characteristics of various types of soil (both cohesive and non-cohesive) for the selection of structural design solutions for the protection elements of critical infrastructure was emphasized. Full article
(This article belongs to the Special Issue Dynamic Behavior of Ceramic Composites and Composite Structures)
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19 pages, 1922 KiB  
Review
Alternative Clinker Technologies for Reducing Carbon Emissions in Cement Industry: A Critical Review
by Mónica Antunes, Rodrigo Lino Santos, João Pereira, Paulo Rocha, Ricardo Bayão Horta and Rogério Colaço
Materials 2022, 15(1), 209; https://doi.org/10.3390/ma15010209 - 28 Dec 2021
Cited by 70 | Viewed by 9399
Abstract
Currently, the production of one ton of ordinary Portland cement (OPC) releases considerable amounts of CO2 into the atmosphere. As the need and demand for this material grows exponentially, it has become a challenge to increase its production at a time when [...] Read more.
Currently, the production of one ton of ordinary Portland cement (OPC) releases considerable amounts of CO2 into the atmosphere. As the need and demand for this material grows exponentially, it has become a challenge to increase its production at a time when climate-related problems represent a major global concern. The two main CO2 contributors in this process are fossil fuel combustion to heat the rotary kiln and the chemical reaction associated with the calcination process, in the production of the clinker, the main component of OPC. The current paper presents a critical review of the existent alternative clinker technologies (ACTs) that are under an investigation trial phase or under restricted use for niche applications and that lead to reduced emissions of CO2. Also, the possibility of transition of clinker production from traditional rotary kilns based on fuel combustion processes to electrification is discussed, since this may lead to the partial or even complete elimination of the CO2 combustion-related emissions, arising from the heating of the clinker kiln. Full article
(This article belongs to the Collection Advanced Civil Engineering Materials: From Synthesis to Application)
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20 pages, 4604 KiB  
Review
Review of Low-Frequency Noise Properties of High-Power White LEDs during Long-Term Aging
by Vilius Palenskis, Jonas Matukas, Justinas Glemža and Sandra Pralgauskaitė
Materials 2022, 15(1), 13; https://doi.org/10.3390/ma15010013 - 21 Dec 2021
Cited by 4 | Viewed by 2905
Abstract
Low-frequency noise investigation is a highly sensitive and very informative method for characterization of white nitride-based light-emitting diodes (LEDs) as well as for the evaluation of their degradation. We present a review of quality and reliability investigations of high-power (1 W and 3 [...] Read more.
Low-frequency noise investigation is a highly sensitive and very informative method for characterization of white nitride-based light-emitting diodes (LEDs) as well as for the evaluation of their degradation. We present a review of quality and reliability investigations of high-power (1 W and 3 W) white light-emitting diodes during long-term aging at the maximum permissible forward current at room temperature. The research was centered on the investigation of blue InGaN and AlInGaN quantum wells (QWs) LEDs covered by a YAG:Ce3+ phosphor layer for white light emission. The current-voltage, light output power, and low-frequency noise characteristics were measured. A broadband silicon photodetector and two-color (blue and red) selective silicon photodetectors were used for the LED output power detection, which makes it possible to separate physical processes related to the initial blue light radiation and the phosphor luminescence. Particular attention was paid to the measurement and interpretation of the simultaneous cross-correlation coefficient between electrical and optical fluctuations. The presented method enables to determine which part of fluctuations originates in the quantum well layer of the LED. The technique using the two-color selective photodetector enables investigation of changes in the noise properties of the main blue light source and the phosphor layer during the long-term aging. Full article
(This article belongs to the Special Issue Advances in Light-Emitting Structures and Materials)
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29 pages, 4600 KiB  
Review
Palm Oil Fuel Ash-Based Eco-Friendly Concrete Composite: A Critical Review of the Long-Term Properties
by Mugahed Amran, Yeong Huei Lee, Roman Fediuk, Gunasekaran Murali, Mohammad Ali Mosaberpanah, Togay Ozbakkaloglu, Yee Yong Lee, Nikolai Vatin, Sergey Klyuev and Maria Karelia
Materials 2021, 14(22), 7074; https://doi.org/10.3390/ma14227074 - 22 Nov 2021
Cited by 30 | Viewed by 6370
Abstract
Rapid global infrastructural developments and advanced material science, amongst other factors, have escalated the demand for concrete. Cement, which is an integral part of concrete, binds the various individual solid materials to form a cohesive mass. Its production to a large extent emits [...] Read more.
Rapid global infrastructural developments and advanced material science, amongst other factors, have escalated the demand for concrete. Cement, which is an integral part of concrete, binds the various individual solid materials to form a cohesive mass. Its production to a large extent emits many tons of greenhouse gases, with nearly 10% of global carbon (IV) oxide (CO2) emanating from cement production. This, coupled with an increase in the advocacy for environmental sustainability, has led to the development of various innovative solutions and supplementary cementitious materials. These aims to substantially reduce the overall volume of cement required in concrete and to meet the consistently increasing demand for concrete, which is projected to increase as a result of rapid construction and infrastructural development trends. Palm oil fuel ash (POFA), an industrial byproduct that is a result of the incineration of palm oil wastes due to electrical generation in power plants has unique properties, as it is a very reactive materials with robust pozzolanic tendencies, and which exhibits adequate micro-filling capabilities. In this study, a review on the material sources, affecting factors, and durability characteristics of POFA are carefully appraised. Moreover, in this study, a review of correlated literature with a broad spectrum of insights into the likely utilization of POFA-based eco-friendly concrete composites as a green material for the present construction of modern buildings is presented. Full article
(This article belongs to the Special Issue Low Carbon Cements)
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32 pages, 7400 KiB  
Review
Catalysts for the Conversion of CO2 to Low Molecular Weight Olefins—A Review
by Barbara Pawelec, Rut Guil-López, Noelia Mota, Jose Luis Garcia Fierro and Rufino Manuel Navarro Yerga
Materials 2021, 14(22), 6952; https://doi.org/10.3390/ma14226952 - 17 Nov 2021
Cited by 33 | Viewed by 5675
Abstract
There is a large worldwide demand for light olefins (C2=–C4=), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + [...] Read more.
There is a large worldwide demand for light olefins (C2=–C4=), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + H2) and hydrogenation of CO2. Among these methods, catalytic hydrogenation of CO2 is the most recently studied because it could contribute to alleviating CO2 emissions into the atmosphere. However, due to thermodynamic reasons, the design of catalysts for the selective production of light olefins from CO2 presents different challenges. In this regard, the recent progress in the synthesis of nanomaterials with well-controlled morphologies and active phase dispersion has opened new perspectives for the production of light olefins. In this review, recent advances in catalyst design are presented, with emphasis on catalysts operating through the modified Fischer–Tropsch pathway. The advantages and disadvantages of olefin production from CO2 via CO or methanol-mediated reaction routes were analyzed, as well as the prospects for the design of a single catalyst for direct olefin production. Conclusions were drawn on the prospect of a new catalyst design for the production of light olefins from CO2. Full article
(This article belongs to the Special Issue Materials for Catalytic CO2 Reduction)
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18 pages, 688 KiB  
Review
A Review of Carbon Footprint Reduction in Construction Industry, from Design to Operation
by Banu Sizirici, Yohanna Fseha, Chung-Suk Cho, Ibrahim Yildiz and Young-Ji Byon
Materials 2021, 14(20), 6094; https://doi.org/10.3390/ma14206094 - 15 Oct 2021
Cited by 188 | Viewed by 18874
Abstract
Construction is among the leading industries/activities contributing the largest carbon footprint. This review paper aims to promote awareness of the sources of carbon footprint in the construction industry, from design to operation and management during manufacturing, transportation, construction, operations, maintenance and management, and [...] Read more.
Construction is among the leading industries/activities contributing the largest carbon footprint. This review paper aims to promote awareness of the sources of carbon footprint in the construction industry, from design to operation and management during manufacturing, transportation, construction, operations, maintenance and management, and end-of-life deconstruction phases. In addition, it summarizes the latest studies on carbon footprint reduction strategies in different phases of construction by the use of alternative additives in building materials, improvements in design, recycling construction waste, promoting the utility of alternative water resources, and increasing efficiencies of water technologies and other building systems. It was reported that the application of alternative additives/materials or techniques/systems can reduce up to 90% of CO2 emissions at different stages in the construction and building operations. Therefore, this review can be beneficial at the stage of conceptualization, design, and construction to assist clients and stakeholders in selecting materials and systems; consequently, it promotes consciousness of the environmental impacts of fabrication, transportation, and operation. Full article
(This article belongs to the Special Issue Sustainable Construction Materials: From Paste to Concrete)
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18 pages, 13502 KiB  
Review
Review of Organic Photorefractive Materials and Their Use for Updateable 3D Display
by Pierre-Alexandre Blanche, Jae-Won Ka and Nasser Peyghambarian
Materials 2021, 14(19), 5799; https://doi.org/10.3390/ma14195799 - 4 Oct 2021
Cited by 25 | Viewed by 5729
Abstract
Photorefractive materials are capable of reversibly changing their index of refraction upon illumination. That property allows them to dynamically record holograms, which is a key function for developing an updateable holographic 3D display. The transition from inorganic photorefractive crystals to organic polymers meant [...] Read more.
Photorefractive materials are capable of reversibly changing their index of refraction upon illumination. That property allows them to dynamically record holograms, which is a key function for developing an updateable holographic 3D display. The transition from inorganic photorefractive crystals to organic polymers meant that large display screens could be made. However, one essential figure of merit that needed to be worked out first was the sensitivity of the material that enables to record bright images in a short amount of time. In this review article, we describe how polymer engineering was able to overcome the problem of the material sensitivity. We highlight the importance of understanding the energy levels of the different species in order to optimize the efficiency and recording speed. We then discuss different photorefractive compounds and the reason for their particular figures of merit. Finally, we consider the technical choices taken to obtain an updateable 3D display using photorefractive polymer. By leveraging the unique properties of this holographic recording material, full color holograms were demonstrated, as well as refreshing rate of 100 hogels/second. Full article
(This article belongs to the Special Issue Photoactive Materials: Synthesis, Applications and Technology (Second Volume))
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22 pages, 1431 KiB  
Review
Recent Advancements in Carbon Nano-Infused Cementitious Composites
by Eryk Goldmann, Marcin Górski and Barbara Klemczak
Materials 2021, 14(18), 5176; https://doi.org/10.3390/ma14185176 - 9 Sep 2021
Cited by 13 | Viewed by 2634
Abstract
A rising demand for efficient functional materials brings forth research challenges regarding improvements in existing materials. Carbon infused cementitious composites, regardless of being an important research topic worldwide, still present many questions concerning their functionality and properties. The paper aims to highlight the [...] Read more.
A rising demand for efficient functional materials brings forth research challenges regarding improvements in existing materials. Carbon infused cementitious composites, regardless of being an important research topic worldwide, still present many questions concerning their functionality and properties. The paper aims to highlight the most important materials used for cementitious composites, their properties, and their uses while also including the most relevant of the latest research in that area. Full article
(This article belongs to the Special Issue Smart Composite Materials for Self-Sensing and Self-Healing in Civil and Environmental Engineering)
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27 pages, 3501 KiB  
Review
Review on the Integration of Microelectronics for E-Textile
by Abdella Ahmmed Simegnaw, Benny Malengier, Gideon Rotich, Melkie Getnet Tadesse and Lieva Van Langenhove
Materials 2021, 14(17), 5113; https://doi.org/10.3390/ma14175113 - 6 Sep 2021
Cited by 80 | Viewed by 8341
Abstract
Modern electronic textiles are moving towards flexible wearable textiles, so-called e-textiles that have micro-electronic elements embedded onto the textile fabric that can be used for varied classes of functionalities. There are different methods of integrating rigid microelectronic components into/onto textiles for the development [...] Read more.
Modern electronic textiles are moving towards flexible wearable textiles, so-called e-textiles that have micro-electronic elements embedded onto the textile fabric that can be used for varied classes of functionalities. There are different methods of integrating rigid microelectronic components into/onto textiles for the development of smart textiles, which include, but are not limited to, physical, mechanical, and chemical approaches. The integration systems must satisfy being flexible, lightweight, stretchable, and washable to offer a superior usability, comfortability, and non-intrusiveness. Furthermore, the resulting wearable garment needs to be breathable. In this review work, three levels of integration of the microelectronics into/onto the textile structures are discussed, the textile-adapted, the textile-integrated, and the textile-based integration. The textile-integrated and the textile-adapted e-textiles have failed to efficiently meet being flexible and washable. To overcome the above problems, researchers studied the integration of microelectronics into/onto textile at fiber or yarn level applying various mechanisms. Hence, a new method of integration, textile-based, has risen to the challenge due to the flexibility and washability advantages of the ultimate product. In general, the aim of this review is to provide a complete overview of the different interconnection methods of electronic components into/onto textile substrate. Full article
(This article belongs to the Special Issue Smart Textile Materials and Fabric-Based Wearable Devices)
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40 pages, 2232 KiB  
Review
A Review on Thermophotovoltaic Cell and Its Applications in Energy Conversion: Issues and Recommendations
by Mansur Mohammed Ali Gamel, Hui Jing Lee, Wan Emilin Suliza Wan Abdul Rashid, Pin Jern Ker, Lau Kuen Yau, Mahammad A. Hannan and Md. Zaini Jamaludin
Materials 2021, 14(17), 4944; https://doi.org/10.3390/ma14174944 - 30 Aug 2021
Cited by 72 | Viewed by 8045
Abstract
Generally, waste heat is redundantly released into the surrounding by anthropogenic activities without strategized planning. Consequently, urban heat islands and global warming chronically increases over time. Thermophotovoltaic (TPV) systems can be potentially deployed to harvest waste heat and recuperate energy to tackle this [...] Read more.
Generally, waste heat is redundantly released into the surrounding by anthropogenic activities without strategized planning. Consequently, urban heat islands and global warming chronically increases over time. Thermophotovoltaic (TPV) systems can be potentially deployed to harvest waste heat and recuperate energy to tackle this global issue with supplementary generation of electrical energy. This paper presents a critical review on two dominant types of semiconductor materials, namely gallium antimonide (GaSb) and indium gallium arsenide (InGaAs), as the potential candidates for TPV cells. The advantages and drawbacks of non-epitaxy and epitaxy growth methods are well-discussed based on different semiconductor materials. In addition, this paper critically examines and summarizes the electrical cell performance of TPV cells made of GaSb, InGaAs and other narrow bandgap semiconductor materials. The cell conversion efficiency improvement in terms of structural design and architectural optimization are also comprehensively analyzed and discussed. Lastly, the practical applications, current issues and challenges of TPV cells are critically reviewed and concluded with recommendations for future research. The highlighted insights of this review will contribute to the increase in effort towards development of future TPV systems with improved cell conversion efficiency. Full article
(This article belongs to the Special Issue Electronic and Optical Properties of Heterostructures)
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33 pages, 4171 KiB  
Review
A State-of-the-Art Review on Integral Transform Technique in Laser–Material Interaction: Fourier and Non-Fourier Heat Equations
by Mihai Oane, Muhammad Arif Mahmood and Andrei C. Popescu
Materials 2021, 14(16), 4733; https://doi.org/10.3390/ma14164733 - 22 Aug 2021
Cited by 15 | Viewed by 3806
Abstract
Heat equations can estimate the thermal distribution and phase transformation in real-time based on the operating conditions and material properties. Such wonderful features have enabled heat equations in various fields, including laser and electron beam processing. The integral transform technique (ITT) is a [...] Read more.
Heat equations can estimate the thermal distribution and phase transformation in real-time based on the operating conditions and material properties. Such wonderful features have enabled heat equations in various fields, including laser and electron beam processing. The integral transform technique (ITT) is a powerful general-purpose semi-analytical/numerical method that transforms partial differential equations into a coupled system of ordinary differential equations. Under this category, Fourier and non-Fourier heat equations can be implemented on both equilibrium and non-equilibrium thermo-dynamical processes, including a wide range of processes such as the Two-Temperature Model, ultra-fast laser irradiation, and biological processes. This review article focuses on heat equation models, including Fourier and non-Fourier heat equations. A comparison between Fourier and non-Fourier heat equations and their generalized solutions have been discussed. Various components of heat equations and their implementation in multiple processes have been illustrated. Besides, literature has been collected based on ITT implementation in various materials. Furthermore, a future outlook has been provided for Fourier and non-Fourier heat equations. It was found that the Fourier heat equation is simple to use but involves infinite speed heat propagation in comparison to the non-Fourier heat equation and can be linked with the Two-Temperature Model in a natural way. On the other hand, the non-Fourier heat equation is complex and involves various unknowns compared to the Fourier heat equation. Fourier and Non-Fourier heat equations have proved their reliability in the case of laser–metallic materials, electron beam–biological and –inorganic materials, laser–semiconducting materials, and laser–graphene material interactions. It has been identified that the material properties, electron–phonon relaxation time, and Eigen Values play an essential role in defining the precise results of Fourier and non-Fourier heat equations. In the case of laser–graphene interaction, a restriction has been identified from ITT. When computations are carried out for attosecond pulse durations, the laser wavelength approaches the nucleus-first electron separation distance, resulting in meaningless results. Full article
(This article belongs to the Special Issue Materials Thermal Behavior during Laser or Electron Beam Irradiation)
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29 pages, 7098 KiB  
Review
Survey of Mechanical Properties of Geopolymer Concrete: A Comprehensive Review and Data Analysis
by Azad A. Mohammed, Hemn Unis Ahmed and Amir Mosavi
Materials 2021, 14(16), 4690; https://doi.org/10.3390/ma14164690 - 20 Aug 2021
Cited by 105 | Viewed by 7134
Abstract
Mechanical properties and data analysis for the prediction of different mechanical properties of geopolymer concrete (GPC) were investigated. A relatively large amount of test data from 126 past works was collected, analyzed, and correlation between different mechanical properties and compressive strength was investigated. [...] Read more.
Mechanical properties and data analysis for the prediction of different mechanical properties of geopolymer concrete (GPC) were investigated. A relatively large amount of test data from 126 past works was collected, analyzed, and correlation between different mechanical properties and compressive strength was investigated. Equations were proposed for the properties of splitting tensile strength, flexural strength, modulus of elasticity, Poisson’s ratio, and strain corresponding to peak compressive strength. The proposed equations were found accurate and can be used to prepare a state-of-art report on GPC. Based on data analysis, it was found that there is a chance to apply some past proposed equations for predicting different mechanical properties. CEB-FIP equations for the prediction of splitting tensile strength and strain corresponding to peak compressive stress were found to be accurate, while ACI 318 equations for splitting tensile and elastic modulus overestimates test data for GPC of low compressive strength. Full article
(This article belongs to the Special Issue Sustainability in Construction and Building Materials)
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