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The Composite Materials of Today and Tomorrow

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Composites".

Deadline for manuscript submissions: closed (20 December 2023) | Viewed by 15367

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Special Issue Editors

Dr. Florian Ion Tiberiu Petrescu

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Guest Editor

1. Theory of Mechanisms and Robots Department, Faculty of Industrial Engineering and Robotics, University POLITEHNICA of Bucharest, Splaiul Independentei Street 313, 060042 Bucharest, Romania
2. Nanomaterials Research Group, Department of Natural Sciences and Technology, Division of Natural Sciences, Technology and Environment, Universidad Ana G. Méndez-Gurabo Campus, Gurabo, PR 00778, USA
Interests: machines; bioengineering; nuclear power; materials science; aerospace
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Francisco Márquez

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Nanomaterials Research Group, Department of Natural Sciences and Technology, Division of Natural Sciences, Technology and Environment, Universidad Ana G. Méndez-Gurabo Campus, Gurabo 00778PR, Puerto Rico
Interests: catalysis; carbon nanotubes; hydrogen; environmental chemistry; photodegradation; Li-ion batteries; energy
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Dr. Gang Shi

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Guest Editor

Key Laboratory of Synthetic and Biotechnology Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China
Interests: photoelectric energy materials and sensing materials; solar-thermal conversion; bio-inspired interface assembly of materials; extraction and application of natural polymer
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Due to their excellent properties, composite materials, biocomposites, or composites with organic matrixes attract special attention in a number of industries, such as aerospace, automotive, maritime, sports, energy, civil engineering, and electrical fields. These materials are light and non-corrosive, and their amazing properties make them adaptable in various fields, especially due to the wide variety of reinforcements—most often fibrous (glass, carbon, and lignocellulosic) but also non-fibrous (hollow microspheres) and matrices (thermo-rigid or thermoplastic). Composite materials are constantly and reliably evolving.

To date, thermosetting matrices have been the most widely used matrices for structural parts. The use of thermoplastic materials even for large parts is due to their hardness and recyclability in comparison to thermosets. Natural fiber reinforcements have interesting characteristics for secondary parts: they are light, environmentally friendly, relatively cheap, renewable, and with sufficiently high stiffness and strength. Furthermore, to improve out-of-plane thickness properties when needed, 3D composites have been developed.

In recent years, the introduction of multifunctional composite material systems has made it possible to further improve primary functions such as stiffness associated with lightness by combining thermoforming and injection manufacturing processes (over rolled laminates) or impact behavior by using composites reinforced with different types of fibers, some chosen for stiffness and others for damping capacity (carbon and linen).

This Special Issue focuses on the development of new composites, especially multifunctional composites, and the study of their properties (including long-term behavior).

Topics of interest include, but are not limited to, the following:

New components (die, fittings) and fabrication;
Composites with silicon, carbon, polymers, rubber, sand, sawdust, glass, plastic, nanoparticles of silver, gold, diamonds, etc.;
Ecological composite materials (matrix, reinforcements);
Structural health monitoring (sensors and actuators);
Biocomposites;
Meta-composites.

Dr. Florian Ion Tiberiu Petrescu
Prof. Dr. Francisco Márquez
Dr. Gang Shi
Guest Editors

Manuscript Submission Information

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

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

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Composite
Cement
Concrete
Nanomaterials
High-performance composites
Biocomposites
Durable, self-healing, eco-friendly composites
Manufacturing.

Published Papers (13 papers)

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Research

27 pages, 3975 KiB

Open AccessArticle

Advanced Composite Materials Utilized in FDM/FFF 3D Printing Manufacturing Processes: The Case of Filled Filaments

by Antreas Kantaros, Evangelos Soulis, Florian Ion Tiberiu Petrescu and Theodore Ganetsos

Materials 2023, 16(18), 6210; https://doi.org/10.3390/ma16186210 - 14 Sep 2023

Cited by 7 | Viewed by 1747

Abstract

The emergence of additive manufacturing technologies has brought about a significant transformation in several industries. Among these technologies, Fused Deposition Modeling/Fused Filament Fabrication (FDM/FFF) 3D printing has gained prominence as a rapid prototyping and small-scale production technique. The potential of FDM/FFF for applications that require improved mechanical, thermal, and electrical properties has been restricted due to the limited range of materials that are suitable for this process. This study explores the integration of various reinforcements, including carbon fibers, glass fibers, and nanoparticles, into the polymer matrix of FDM/FFF filaments. The utilization of advanced materials for reinforcing the filaments has led to the enhancement in mechanical strength, stiffness, and toughness of the 3D-printed parts in comparison to their pure polymer counterparts. Furthermore, the incorporation of fillers facilitates improved thermal conductivity, electrical conductivity, and flame retardancy, thereby broadening the scope of potential applications for FDM/FFF 3D-printed components. Additionally, the article underscores the difficulties linked with the utilization of filled filaments in FDM/FFF 3D printing, including but not limited to filament extrusion stability, nozzle clogging, and interfacial adhesion between the reinforcement and matrix. Ultimately, a variety of pragmatic implementations are showcased, wherein filled filaments have exhibited noteworthy benefits in comparison to standard FDM/FFF raw materials. The aforementioned applications encompass a wide range of industries, such as aerospace, automotive, medical, electronics, and tooling. The article explores the possibility of future progress and the incorporation of innovative reinforcement materials. It presents a plan for the ongoing growth and application of advanced composite materials in FDM/FFF 3D printing. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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11 pages, 2316 KiB

Open AccessArticle

Effect of Template–Mediated Alumina Nanoparticle Morphology on Sapphire Wafer Production via Heat Exchange Method

by Yadian Xie, Miaoxuan Xue, Lanxing Gao, Yanqing Hou, Bo Yang and Xin Tong

Materials 2023, 16(17), 5938; https://doi.org/10.3390/ma16175938 - 30 Aug 2023

Viewed by 679

Abstract

The sapphire crystal, the most commonly used LED substrate material, has excellent optical and chemical properties and has rapidly developed in recent years. However, the challenge of growing large–size sapphire crystals remains. This paper presents a novel approach using alumina nanoparticles synthesized with abietic acid as a template to enhance sapphire growth via the heat exchange method. This study explores the effects of temperature, time, and template amount on the structure and morphology of the synthesized alumina nanoparticles. The results show that the morphology of the raw material, particularly spherical alumina nanoparticles, positively affects the quality and yield stability of sapphire products. Furthermore, the light output power of GaN–based LED chips made with the experimentally fabricated sapphire substrate increased from 3.47 W/µm² to 3.71 W/µm², a 6.9% increase compared to commercially available sapphire substrates. This research highlights the potential of using abietic acid as a template for alumina nanoparticle synthesis and their application in sapphire growth for LED production. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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15 pages, 7478 KiB

Open AccessArticle

Surface Roughening of Irradiation-Activated Basalt Fiber through In Situ Growth of SiO₂: Effects on Crystallization and Properties of PP Composites

by Shuai Zhang, Pan He, Shuoyi Jing, Gang Chen, Guangzhao Li, Zhongzui Wang, Rui Han and Yijun Li

Materials 2023, 16(16), 5657; https://doi.org/10.3390/ma16165657 - 17 Aug 2023

Viewed by 864

Abstract

Basalt fiber (BF) is deemed a new environmentally friendly and high-performance fiber material due to its high strength, electrical insulation, corrosion resistance and high temperature resistance. Yet, the surface inertness restricts its practical application. In this work, the BF was irradiated and activated by electron beam, followed by in situ growth of SiO₂ using a hydrothermal method, then composites with polypropylene (PP) were prepared by microinjection molding. According to the results of scanning electron microscopy (SEM) and Fourier transform infrared (FTIR), more active sites can be formed after irradiation, thus more SiO₂ nanoparticles were generated on the surface of BF. Consequently, the rough surface of modified BF could provide stronger shear force during melt processing and resulted in a higher orientation of the molecular chains, increasing the lamellar thickness and generating more highly ordered β crystals in the composites. I₄₀₀BF-gSiO₂ exhibited the highest content of β crystals with the crystallinity of 53.62% and orientation of β (300) crystal plane of 0.91, which were 8.66% and 0.04 higher than those of the composite with pristine BF. Furthermore, due to the perfection of crystals, increased interfaces and interfacial interlocking between PP molecules and modified BF, I₄₀₀BF-gSiO₂ showed good overall performance, with storage modulus of 8000 MPa at −100 °C, glass transition temperature of 23.03 °C and tensile strength of 62.2 MPa, which was 1900 MPa, 1.23 °C and 29.6 MPa higher than neat PP. Hence, the surface roughing strategy proposed in this work is expected to provide some insight and promote the application of BF reinforced thermoplastic composites. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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17 pages, 6741 KiB

Open AccessArticle

Experimental and Theoretical Studies of Hydrogen Storage in LaNi_4.4Al_0.3Fe_0.3 Hydride Bed

by Chaker Briki, Dmitry Dunikov, Maha M. Almoneef, Ivan Romanov, Alexey Kazakov, Mohamed Mbarek and Jemni Abdelmajid

Materials 2023, 16(15), 5425; https://doi.org/10.3390/ma16155425 - 02 Aug 2023

Cited by 2 | Viewed by 776

Abstract

In this article, the experimental measurements of the absorption/desorption P–C–T isotherms of hydrogen in the LaNi_4.4Fe_0.3Al_0.3 alloy at different temperatures and constant hydrogen pressure have been studied using a numerical model. The mathematics equations of this model contain parameters, such as the two terms, n_α and n_β, representing the numbers of hydrogen atoms per site; N_mα and N_mβ are the receptor sites’ densities, and the energetic parameters are P_α and P_β. All these parameters are derived by numerically adjusting the experimental data. The profiles of these parameters during the absorption/desorption process are studied as a function of temperature. Thereafter, we examined the evolution of the internal energy versus temperature, which typically ranges between 138 and 181 kJmol⁻¹ for the absorption process and between 140 and 179 kJmol⁻¹ for the desorption process. The evolution of thermodynamic functions with pressure, for example, entropy, Gibbs free energy (G), and internal energy, are determined from the experimental data of the hydrogen absorption and desorption isotherms of the LaNi_4.4A_l0.3F_e0.3 alloy. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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16 pages, 1681 KiB

Open AccessArticle

Thermal Mechanical Bending Response of Symmetrical Functionally Graded Material Plates

by Mengna Han, Zichan Li, Zhicheng Huang, Xingguo Wang and Wenjie Gao

Materials 2023, 16(13), 4683; https://doi.org/10.3390/ma16134683 - 28 Jun 2023

Cited by 1 | Viewed by 805

Abstract

This paper investigates the thermal mechanical bending response of symmetric functionally graded material (FGM) plates. This article proposes a thermodynamic analysis model of both the FGM plate and FGM sandwich plate, and the model only involves four control equations and four unknown variables. The control equation is based on the refined shear deformation theory and the principle of minimum potential energy. The Navier method is used to solve the control equation. According to the method, numerical examples are provided for the thermo-mechanical bending of the symmetric FGM plate and FGM sandwich plate under a simply supported boundary condition, and the accuracy of the model is verified. Finally, parameter analysis is conducted to investigate the effects of the volume fraction index, side-to-thickness ratio, thermal load, and changes in core thickness on the thermal mechanical bending behavior of the symmetric FGM plate and FGM sandwich plate in detail. It was found that the deflection of the FGM plate is greater than that of the FGM sandwich plate, while the normal stress of the FGM plate is smaller than that of the FGM sandwich plate. Moreover, the FGM plate and FGM sandwich plate are sensitive to nonlinear temperature changes. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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14 pages, 1718 KiB

Open AccessArticle

Bending Analysis of Asymmetric Functionally Graded Material Sandwich Plates in Thermal Environments

by Mengna Han, Jiahao Huang, Zhicheng Huang and Xingguo Wang

Materials 2023, 16(13), 4682; https://doi.org/10.3390/ma16134682 - 28 Jun 2023

Cited by 1 | Viewed by 748

Abstract

This paper investigates the bending of asymmetric functionally graded material (FGM) sandwich plates subjected to thermo-mechanical loads in thermal environments. In this paper, a thermo-mechanical analysis model for asymmetric FGM sandwich plates is proposed, which contains only four control equations and four unknown variables. The governing equation is obtained through refined shear theory and the principle of virtual work, and the Navier method is used to solve it. Numerical examples of simply supported FGM sandwich plates under thermo-mechanical loads are given to verify the accuracy of the model. Finally, detailed studies are conducted on the bending of asymmetric FGM sandwich plates under thermo-mechanical loads, exploring the effects of various parameter changes on their bending behavior, and providing strong guidance for the application of asymmetric FGM sandwich plates in industrial production practice. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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21 pages, 12105 KiB

Open AccessArticle

Distinct Optical and Structural (Nanoyarn and Nanomat-like Structure) Characteristics of Zinc Oxide Nanofilm Derived by Using Salvia officinalis Leaves Extract Made without and with PEO Polymer

by Adnan H. Alrajhi, Naser M. Ahmed, Mohd Mahadi Halim, Abeer S. Altowyan, Mohamad Nurul Azmi and Munirah A. Almessiere

Materials 2023, 16(13), 4510; https://doi.org/10.3390/ma16134510 - 21 Jun 2023

Cited by 2 | Viewed by 806

Abstract

This paper reports the optical properties of zinc oxide nanofilm fabricated by using organic natural products from Salvia officinalis leaves (SOL) extract and discusses the effect of the nanocrystal (NC) structure (nanoyarn and nanomat-like structure) on nanofilm optical properties. The surface-active layer of the nanofilm of ZnO nanoparticles (ZnO NPs) was passivated with natural organic SOL leaves hydrothermally, then accumulated on zinc oxide nanorods (ZnO NRs). The nanofilms were fabricated (with and without PEO) on glass substrate (at 85 °C for 16 h) via chemical solution deposition (CSD). The samples were characterized by UV-vis, PL, FESEM, XRD, and TEM measurements. TEM micrographs confirmed the nucleation of ZnO NPs around 4 nm and the size distribution at 1.2 nm of ZnO QDs as an influence of the quantum confinement effect (QCE). The nanofilms fabricated with SOL surfactant (which works as a capping agent for ZnO NPs) represent distinct optoelectronic properties when compared to bulk ZnO. FESEM images of the nanofilms revealed nanoyarn and nanomat-like structures resembling morphologies. The XRD patterns of the samples exhibited the existence of ZnO nanocrystallites (ZnO NCs) with (100), (002), and (101) growth planes. The nanofilms fabricated represented a distinct optical property through absorption and broad emission, as the optical energy band gap reduced as the nanofilms annealed (at

120 ℃

). Based on the obtained results, it was established that phytochemicals extracted from organic natural SOL leaves have a distinct influence on zoic oxide nanofilm fabrication, which may be useful for visible light spectrum trapping. The nanofilms can be used in photovoltaic solar cell applications. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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19 pages, 5439 KiB

Open AccessArticle

Peumus boldus Used in the Synthesis of ZnO Semiconductor Nanoparticles and Their Evaluation in Organic Contaminants

by Caree Abigail García Maro, Horacio Edgardo Garrafa Gálvez, Osvaldo de Jesús Nava Olivas, Mizael Luque Morales, Diana Vargas Hernández, Hugo Galindo Flores, Víctor Manuel Orozco Carmona and Manuel de Jesús Chinchillas Chinchillas

Materials 2023, 16(12), 4344; https://doi.org/10.3390/ma16124344 - 13 Jun 2023

Cited by 3 | Viewed by 862

Abstract

The high demand for nanomaterials in the field of industry and science has forced researchers to develop new synthesis methods that are more efficient, economical, and environmentally friendly. At present, the application of green synthesis has taken a great advantage over conventional synthesis methods because it helps with the control of the characteristics and properties of the resulting nanomaterials. In this research, ZnO nanoparticles (NPs) were synthesized by biosynthesis using dried boldo (Peumus boldus) leaves. The resulting biosynthesized NPs had a high purity, quasi-spherical shape with average sizes ranging from 15 to 30 nm and a band gap of ~2.8–3.1 eV. These NPs were used in the photocatalytic activity of three organic dyes. The results showed degradation of 100% methylene blue (MB) in 180 min, 92% methyl orange (MO) in 180 min, and 100% Rhodamine B (RhB) in 30 min of exposure. These results show that the Peumus boldus leaf extract is effective in the biosynthesis of ZnO NPs with good photocatalytic properties. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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22 pages, 8320 KiB

Open AccessArticle

Failure Mechanism and Control Countermeasures for Argillaceous Surrounding Rock of Horsehead Roadway under High Stress

by Deyu Qian, Qi Cui, Hexi Jiao, Guanghui Zhu, Zhiyi Zhang, Linyou Jiang, Qingbin Meng, Jiale Liu, Xing Gao and Fujia Xing

Materials 2023, 16(11), 4180; https://doi.org/10.3390/ma16114180 - 04 Jun 2023

Viewed by 903

Abstract

The argillaceous surrounding rock of a horsehead roadway under high stress conditions is prone to deformation and failure, and the control of its long-term stability is difficult. Based on the engineering practices that control the argillaceous surrounding rock of a horsehead roadway in the return air shaft in the Libi Coal Mine in Shanxi Province, field measurements, laboratory experimentation, numerical simulation, and industrial tests are used to analyze the main influencing factors and mechanism of the deformation and failure of the surrounding rock of the horsehead roadway. We propose principles and countermeasures to control the stability of the horsehead roadway. The main factors of the surrounding rock failure of the horsehead roadway include the poor lithology of argillaceous surrounding rocks, horizontal tectonic stress, the superimposed influence of additional stress from the shaft and construction disturbance, the small thickness of the anchorage layer in the roof, and the insufficient depth of floor reinforcement. The results show that the shaft’s presence increases the horizontal stress peak and stress concentration range in the roof, and the plastic zone range. The stress concentration and plastic zones and deformations of the surrounding rock increase significantly with the increase in horizontal tectonic stress. The control principles for the argillaceous surrounding rock of the horsehead roadway include increasing the thickness of the anchorage ring, the floor reinforcement exceeding the minimum depth, and reinforced support in key positions. The key control countermeasures include an innovative prestressed full-length anchorage for the mudstone roof, active and passive reinforcement technology with cables, and a reverse arch for floor reinforcement. The field measurements show that the control of the surrounding rock using the prestressed full-length anchorage of the innovative anchor-grouting device is remarkable. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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17 pages, 6953 KiB

Open AccessArticle

The Impact of 3D Prism Cavity for Enhanced Oil Recovery Using Different Nanomaterials

by Mudasar Zafar, Hamzah Sakidin, Iskandar Dzulkarnain, Abida Hussain, Mikhail Sheremet, Roslinda Nazar, Abdullah Al-Yaari, Nur Asyatulmaila Mohamad Asri and Shazia Bashir

Materials 2023, 16(11), 4011; https://doi.org/10.3390/ma16114011 - 27 May 2023

Cited by 2 | Viewed by 1024

Abstract

Enhanced oil recovery (EOR) has been offered as an alternative to declining crude oil production. EOR using nanotechnology is one of the most innovative trends in the petroleum industry. In order to determine the maximum oil recovery, the effect of a 3D rectangular prism shape is numerically investigated in this study. Using ANSYS Fluent software(2022R1), we develop a two-phase mathematical model based on 3D geometry. This research examines the following parameters: flow rate Q = 0.01–0.05 mL/min, volume fractions = 0.01–0.04%, and the effect of nanomaterials on relative permeability. The result of the model is verified with published studies. In this study, the finite volume method is used to simulate the problem, and we run simulations at different flow rates while keeping other variables constant. The findings show that the nanomaterials have an important effect on water and oil permeability, increasing oil mobility and lowering IFT, which increases the recovery process. Additionally, it has been noted that a reduction in the flow rate improves oil recovery. Maximum oil recovery was attained at a 0.05 mL/min flow rate. Based on the findings, it is also demonstrated that Si

O_{2}

provides better oil recovery compared to A

l_{2} O_{3}

. When the volume fraction concentration increases, oil recovery ultimately increases. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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13 pages, 10325 KiB

Open AccessArticle

Spiropyran-Based Soft Substrate with SPR, Anti-Reflection and Anti-NRET for Enhanced Visualization/Fluorescence Dual Response to Metal Ions

by Yuebo Jin, Florian Ion Tiberiu Petrescu, Yuan Wang, Xin Li, Ying Li and Gang Shi

Materials 2023, 16(10), 3746; https://doi.org/10.3390/ma16103746 - 15 May 2023

Cited by 1 | Viewed by 963

Abstract

The photoluminescence of modified spiropyran on solid surfaces is poor, and the fluorescence intensity of its MC form is weak, which affects its application in the field of sensing. In this work, a PMMA layer containing Au nanoparticles and a spiropyran monomolecular layer are coated on the surface of a PDMS substrate with inverted micro-pyramids successively by means of interface assembly and soft lithography, and the overall structure is similar to insect compound eyes. The anti-reflection effect of the bioinspired structure, the SPR (surface plasmon resonance) effect of the Au nanoparticles and the anti-NRET (non-radiation energy transfer) effect of the PMMA isolation layer raise the fluorescence enhancement factor of the composite substrate vs. the surface MC form of spiropyran to 5.06. In the process of metal ion detection, the composite substrate can achieve both colorimetric and fluorescence response, and the detection limit for Zn²⁺ can reach 0.281 μM. However, at the same time, the lack of the ability to recognize specific metal ions is expected to be further improved by the modification of spiropyran. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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19 pages, 3287 KiB

Open AccessArticle

Hydrogen Dissociation Reaction on First-Row Transition Metal Doped Nanobelts

by Imene Bayach, Sehrish Sarfaraz, Nadeem S. Sheikh, Kawther Alamer, Nadiah Almutlaq and Khurshid Ayub

Materials 2023, 16(7), 2792; https://doi.org/10.3390/ma16072792 - 31 Mar 2023

Cited by 6 | Viewed by 1137

Abstract

Zigzag molecular nanobelts have recently captured the interest of scientists because of their appealing aesthetic structures, intriguing chemical reactivities, and tantalizing features. In the current study, first-row transition metals supported on an H₆-N₃-belt[6]arene nanobelt are investigated for the electrocatalytic properties of these complexes for the hydrogen dissociation reaction (HDR). The interaction of the doped transition metal atom with the nanobelt is evaluated through interaction energy analysis, which reveals the significant thermodynamic stability of TM-doped nanobelt complexes. Electronic properties such as frontier molecular orbitals and natural bond orbitals analyses are also computed, to estimate the electronic perturbation upon doping. The highest reduction in the HOMO–LUMO energy gap compared to the bare nanobelt is seen in the case of the Zn@NB catalyst (4.76 eV). Furthermore, for the HDR reaction, the Sc@NB catalyst displays the best catalytic activity among the studied catalysts, with a hydrogen dissociation barrier of 0.13 eV, whereas the second-best catalytic activity is observed for the Zn@NB catalyst (0.36 eV). It is further found that multiple active sites, i.e., the presence of the metal atom and nitrogen atom moiety, help to facilitate the dissociation of the hydrogen molecule. These key findings of this study enhance the understanding of the relative stability, electronic features, and catalytic bindings of various TM@NB catalysts. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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13 pages, 14714 KiB

Open AccessArticle

Synthesis of ZnO Nanoflower Arrays on Patterned Cavity Substrate and Their Application in Methylene Blue Degradation

by Xin Zhao, Ching-Shan Wang, Ni-Ni Chou, Fang-Hsing Wang and Cheng-Fu Yang

Materials 2023, 16(7), 2647; https://doi.org/10.3390/ma16072647 - 27 Mar 2023

Cited by 3 | Viewed by 985

Abstract

A novel method was proposed to fabricate a ZnO seed layer with a protrusion and matrix structure, and then ZnO nanorods could be synthesized on it using the hydrothermal method to form ZnO nanoflower arrays (NFAs) easily. A patterned sapphire with a matrix cavity was used as the template, ZnO gel was deposited on the multilayer substrates using spinning coating, and the prepared seed layer with a protrusion and an array-patterned structure was moved to a Si substrate using the lift-off method. Because the ZnO seed layer exhibited a matrix and protrusion structure, ZnO nanorods were grown vertically downwards and formed ZnO NFAs. The XRD patterns resulting from analyses showed that the diffraction peaks of the five growth directions of ZnO NFAs increased as growth time increased. Furthermore, SEM and FIB analyses indicated that the length, width, aspect ratio, and total surface area of ZnO NFAs grown on the transferred seed layer increased as the synthesis time increased. Different ZnO NFAs synthesized for varying synthesis times were used to investigate methylene blue degradation, with the effect of ZnO NFAs on methylene blue degradation determined using the Beer–Lambert law. Our results demonstrate that the effect of ZnO NFAs on methylene blue degradation was enhanced with increasing synthesis time. Full article

(This article belongs to the Special Issue The Composite Materials of Today and Tomorrow)

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