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Nanomaterials, Volume 13, Issue 22 (November-2 2023) – 72 articles

Cover Story (view full-size image): Exopolysaccharides are biopolymers obtained from microorganisms; they could be fully valorized to obtain nanostructured devices for tissue engineering. Porous structures are the ultimate product of the sol–gel route, whose final step is the removal of the liquid phase from the polymeric network (drying). This review aims at pointing out the differences between drying techniques to pin the most effective route to obtain exopolysaccharide-based porous devices of biomedical interest. Supercritical CO2 drying (which produces aerogels) is the main technique that preserves gels’ nanostructure, thus forming a bridge between morphology and biomechanical performances, which is crucial for biomedical applications. View this paper
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14 pages, 1616 KiB  
Article
Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites
Nanomaterials 2023, 13(22), 2980; https://doi.org/10.3390/nano13222980 - 20 Nov 2023
Viewed by 578
Abstract
We explore the influence of functionalized core–shell CdSe/ZnS quantum dots on the properties of the host liquid crystal compound 4-cyano-4′-octylbiphenyl (8CB) through electrooptical measurements. Two different diameters of quantum dots are used to investigate the size effects. We assess both the dispersion quality [...] Read more.
We explore the influence of functionalized core–shell CdSe/ZnS quantum dots on the properties of the host liquid crystal compound 4-cyano-4′-octylbiphenyl (8CB) through electrooptical measurements. Two different diameters of quantum dots are used to investigate the size effects. We assess both the dispersion quality of the nanoparticles within the mixtures and the phase stability of the resulting anisotropic soft nanocomposites using polarizing optical microscopy. The temperature-mass fraction phase diagrams of the nanocomposites reveal deviations from the linear behavior in the phase stability lines. We measure the birefringence, the threshold voltage of the Fréedericksz transition, and the electrooptic switching times of the nanocomposite systems in planar cell geometry as functions of temperature, mass fraction, and diameter of the quantum dots. Beyond a critical mass fraction of the dopant nanoparticles, the nematic order is strongly reduced. Furthermore, we investigate the impact of the nanoparticle size and mass fraction on the viscoelastic coefficient. The anchoring energy at the interfaces of the liquid crystal with the cell and the quantum dots is estimated. Full article
(This article belongs to the Special Issue Current Research in Nematic Liquid Crystal Nanocomposites)
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13 pages, 1985 KiB  
Article
Deep-Ultraviolet Transparent Electrode Design for High-Performance and Self-Powered Perovskite Photodetector
Nanomaterials 2023, 13(22), 2979; https://doi.org/10.3390/nano13222979 - 20 Nov 2023
Viewed by 577
Abstract
In this study, a highly crystalline and transparent indium-tin-oxide (ITO) thin film was prepared on a quartz substrate via RF sputtering to fabricate an efficient bottom-to-top illuminated electrode for an ultraviolet C (UVC) photodetector. Accordingly, the 26.6 nm thick ITO thin film, which [...] Read more.
In this study, a highly crystalline and transparent indium-tin-oxide (ITO) thin film was prepared on a quartz substrate via RF sputtering to fabricate an efficient bottom-to-top illuminated electrode for an ultraviolet C (UVC) photodetector. Accordingly, the 26.6 nm thick ITO thin film, which was deposited using the sputtering method followed by post-annealing treatment, exhibited good transparency to deep-UV spectra (67% at a wavelength of 254 nm), along with high electrical conductivity (11.3 S/cm). Under 254 nm UVC illumination, the lead-halide-perovskite-based photodetector developed on the prepared ITO electrode in a vertical structure exhibited an excellent on/off ratio of 1.05 × 104, a superb responsivity of 250.98 mA/W, and a high specific detectivity of 4.71 × 1012 Jones without external energy consumption. This study indicates that post-annealed ITO ultrathin films can be used as electrodes that satisfy both the electrical conductivity and deep-UV transparency requirements for high-performance bottom-illuminated optoelectronic devices, particularly for use in UVC photodetectors. Full article
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10 pages, 2183 KiB  
Article
Resistive Switching in Bigraphene/Diamane Nanostructures Formed on a La3Ga5SiO14 Substrate Using Electron Beam Irradiation
Nanomaterials 2023, 13(22), 2978; https://doi.org/10.3390/nano13222978 - 20 Nov 2023
Cited by 1 | Viewed by 700
Abstract
Memristors, resistive switching memory devices, play a crucial role in the energy-efficient implementation of artificial intelligence. This study investigates resistive switching behavior in a lateral 2D composite structure composed of bilayer graphene and 2D diamond (diamane) nanostructures formed using electron beam irradiation. The [...] Read more.
Memristors, resistive switching memory devices, play a crucial role in the energy-efficient implementation of artificial intelligence. This study investigates resistive switching behavior in a lateral 2D composite structure composed of bilayer graphene and 2D diamond (diamane) nanostructures formed using electron beam irradiation. The resulting bigraphene/diamane structure exhibits nonlinear charge carrier transport behavior and a significant increase in resistance. It is shown that the resistive switching of the nanostructure is well controlled using bias voltage. The impact of an electrical field on the bonding of diamane-stabilizing functional groups is investigated. By subjecting the lateral bigraphene/diamane/bigraphene nanostructure to a sufficiently strong electric field, the migration of hydrogen ions and/or oxygen-related groups located on one or both sides of the nanostructure can occur. This process leads to the disruption of sp3 carbon bonds, restoring the high conductivity of bigraphene. Full article
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10 pages, 2207 KiB  
Article
Nontraditional Movement Behavior of Skyrmion in a Circular-Ring Nanotrack
Nanomaterials 2023, 13(22), 2977; https://doi.org/10.3390/nano13222977 - 20 Nov 2023
Viewed by 677
Abstract
Magnetic skyrmions are considered promising candidates for use as information carriers in future spintronic devices. To achieve the development of skyrmion-based spintronic devices, a reasonable and feasible nanotrack is essential. In this paper, we conducted a study on the current-driven skyrmion movement in [...] Read more.
Magnetic skyrmions are considered promising candidates for use as information carriers in future spintronic devices. To achieve the development of skyrmion-based spintronic devices, a reasonable and feasible nanotrack is essential. In this paper, we conducted a study on the current-driven skyrmion movement in a circular-ring-shaped nanotrack. Our results suggest that the asymmetry of the inside and outside boundary of the circular ring changed the stable position of the skyrmion, causing it to move like the skyrmion Hall effect when driven by currents. Moreover, the asymmetric boundaries have advantages in enhancing or weakening the skyrmion Hall effect. Additionally, we also compared the skyrmion Hall effect from the asymmetric boundary of circular-ring nanotracks with that from the inhomogeneous Dzyaloshinskii–Moriya interaction. It was found that the skyrmion Hall effect in the circular ring is significantly greater than that caused by the inhomogeneous Dzyaloshinskii–Moriya interaction. These results contribute to our understanding of the skyrmion dynamics in confined geometries and offer an alternative method for controlling the skyrmion Hall effect of skyrmion-based devices. Full article
(This article belongs to the Special Issue Advances in Nanoscale Magnetism and Spintronics)
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14 pages, 5696 KiB  
Article
Template-Free Manufacturing of Defined Structure and Size Polymeric Microparticles
Nanomaterials 2023, 13(22), 2976; https://doi.org/10.3390/nano13222976 - 20 Nov 2023
Cited by 1 | Viewed by 668
Abstract
Complex-structured polymeric microparticles hold significant promise as an advance in next-generation medicine mostly due to demand from developing targeted drug delivery. However, the conventional methods for producing these microparticles of defined size, shape, and sophisticated composition often face challenges in scalability, reliance on [...] Read more.
Complex-structured polymeric microparticles hold significant promise as an advance in next-generation medicine mostly due to demand from developing targeted drug delivery. However, the conventional methods for producing these microparticles of defined size, shape, and sophisticated composition often face challenges in scalability, reliance on specialized components such as micro-patterned templates, or limited control over particle size distribution and cargo (functional payload) release kinetics. In this study, we introduce a novel and reliably scalable approach for manufacturing microparticles of defined structures and sizes with variable parameters. The concept behind this method involves the deposition of a specific number of polymer layers on a substrate with low surface energy. Each layer can serve as either the carrier for cargo or a programmable shell-former with predefined permeability. Subsequently, this layered structure is precisely cut into desired-size blanks (particle precursors) using a laser. The manufacturing process is completed by applying heat to the substrate, which results in sealing the edges of the blanks. The combination of the high surface tension of the molten polymer and the low surface energy of the substrate enables the formation of discrete particles, each possessing semi-spherical or other designed geometries determined by their internal composition. Such anisotropic microparticles are envisaged to have versatile applications. Full article
(This article belongs to the Special Issue Micro/Nano-Swimmers, Robots, and Motors: Fabrication and Applications)
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13 pages, 4946 KiB  
Article
MgO Nanoparticles Obtained from an Innovative and Sustainable Route and Their Applications in Cancer Therapy
Nanomaterials 2023, 13(22), 2975; https://doi.org/10.3390/nano13222975 - 19 Nov 2023
Viewed by 735
Abstract
This paper aimed to evaluate the biological damages towards diseased cells caused by the use of MgO nanoparticles (NPs). The NPs are produced by a calcination process of a precursor, which is an aqueous suspension of nanostructured Mg(OH)2, in turn synthesized [...] Read more.
This paper aimed to evaluate the biological damages towards diseased cells caused by the use of MgO nanoparticles (NPs). The NPs are produced by a calcination process of a precursor, which is an aqueous suspension of nanostructured Mg(OH)2, in turn synthesized following our original, time-energy saving and scalable method able to guarantee short times, high yield of production (up to almost 10 kg/week of NPs), low environmental impact and low energy demand. The MgO NPs, in the form of dry powders, are organized as a network of intercrystallite channels, in turn constituted by monodispersed and roughly spherical NPs < 10 nm, preserving the original pseudo hexagonal-platelet morphology of the precursor. The produced MgO powders are diluted in a PBS solution to obtain different MgO suspension concentrations that are subsequently put in contact, for 3 days, with melanoma and healthy cells. The viable count, made at 24, 48 and 72 h from the beginning of the test, reveals a good cytotoxic activity of the NPs, already at low MgO concentrations. This is particularly marked after 72 h, showing a clear reduction in cellular proliferation in a MgO-concentration-dependent manner. Finally, the results obtained on human skin fibroblasts revealed that the use MgO NPs did not alter at all both the vitality and proliferation of healthy cells. Full article
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25 pages, 9881 KiB  
Article
High-Entropy Lead-Free Perovskite Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties
Nanomaterials 2023, 13(22), 2974; https://doi.org/10.3390/nano13222974 - 19 Nov 2023
Viewed by 817
Abstract
A novel high-entropy perovskite powder with the composition Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 was successfully synthesized using a modified Pechini method. The precursor powder underwent characterization through Fourier Transform Infrared Spectroscopy and thermal analysis. The resultant [...] Read more.
A novel high-entropy perovskite powder with the composition Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 was successfully synthesized using a modified Pechini method. The precursor powder underwent characterization through Fourier Transform Infrared Spectroscopy and thermal analysis. The resultant Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 powder, obtained post-calcination at 900 °C, was further examined using a variety of techniques including X-ray diffraction, Raman spectroscopy, X-ray fluorescence, scanning electron microscopy, and transmission electron microscopy. Ceramic samples were fabricated by conventional sintering at various temperatures (900, 950, and 1000 °C). The structure, microstructure, and dielectric properties of these ceramics were subsequently analyzed and discussed. The ceramics exhibited a two-phase composition comprising cubic and tetragonal perovskites. The grain size was observed to increase from 35 to 50 nm, contingent on the sintering temperature. All ceramic samples demonstrated relaxor behavior with a dielectric maximum that became more flattened and shifted towards lower temperatures as the grain size decreased. Full article
(This article belongs to the Special Issue Nanoscale Ferroelectric Materials and Their Application)
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15 pages, 968 KiB  
Review
Application of Zeolites and Zeolitic Imidazolate Frameworks in Dentistry—A Narrative Review
Nanomaterials 2023, 13(22), 2973; https://doi.org/10.3390/nano13222973 - 18 Nov 2023
Viewed by 1320
Abstract
Zeolites and zeolitic imidazolate frameworks (ZIFs) are crystalline aluminosilicates with porous structure, which are closely linked with nanomaterials. They are characterized by enhanced ion exchange capacity, physical–chemical stability, thermal stability and biocompatibility, making them a promising material for dental applications. This review aimed [...] Read more.
Zeolites and zeolitic imidazolate frameworks (ZIFs) are crystalline aluminosilicates with porous structure, which are closely linked with nanomaterials. They are characterized by enhanced ion exchange capacity, physical–chemical stability, thermal stability and biocompatibility, making them a promising material for dental applications. This review aimed to provide an overview of the application of zeolites and ZIFs in dentistry. The common zeolite compounds for dental application include silver zeolite, zinc zeolite, calcium zeolite and strontium zeolite. The common ZIFs for dental application include ZIF-8 and ZIF-67. Zeolites and ZIFs have been employed in various areas of dentistry, such as restorative dentistry, endodontics, prosthodontics, implantology, periodontics, orthodontics and oral surgery. In restorative dentistry, zeolites and ZIFs are used as antimicrobial additives in dental adhesives and restorative materials. In endodontics, zeolites are used in root-end fillings, root canal irritants, root canal sealers and bone matrix scaffolds for peri-apical diseases. In prosthodontics, zeolites can be incorporated into denture bases, tissue conditioners, soft denture liners and dental prostheses. In implantology, zeolites and ZIFs are applied in dental implants, bone graft materials, bone adhesive hydrogels, drug delivery systems and electrospinning. In periodontics, zeolites can be applied as antibacterial agents for deep periodontal pockets, while ZIFs can be embedded in guided tissue regeneration membranes and guided bone regeneration membranes. In orthodontics, zeolites can be applied in orthodontic appliances. Additionally, for oral surgery, zeolites can be used in oral cancer diagnostic marker membranes, maxillofacial prosthesis silicone elastomer and tooth extraction medicines, while ZIFs can be incorporated to osteogenic glue or used as a carrier for antitumour drugs. In summary, zeolites have a broad application in dentistry and are receiving more attention from clinicians and researchers. Full article
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13 pages, 4348 KiB  
Article
Enhanced Catalytic Performance of Ag NP/0.95AgNbO3-0.05LiTaO3 Heterojunction from the Combination of Surface Plasma Resonance Effect and Piezoelectric Effect Using Facile Mechanical Milling
Nanomaterials 2023, 13(22), 2972; https://doi.org/10.3390/nano13222972 - 18 Nov 2023
Viewed by 688
Abstract
An internal built electric field can suppress the recombination of electron–hole pairs and distinctly enhance the catalytic activity of a photocatalyst. Novel t-Ag/0.95AgNbO3-0.05LiTaO3 heterojunction was prepared by reducing silver nanoparticles (Ag NPs) on the surface of the piezoelectric powder 0.95AgNbO [...] Read more.
An internal built electric field can suppress the recombination of electron–hole pairs and distinctly enhance the catalytic activity of a photocatalyst. Novel t-Ag/0.95AgNbO3-0.05LiTaO3 heterojunction was prepared by reducing silver nanoparticles (Ag NPs) on the surface of the piezoelectric powder 0.95AgNbO3-0.05LiTaO3 (0.05-ANLT) using a simple mechanical milling method. The effects of milling time and excitation source used for the degradation of organic dye by heterojunction catalysts were investigated. The results demonstrate that the optimized 1.5-Ag/0.05-ANLT heterojunction removes 97% RhB within 40 min, which is 7.8 times higher than that of single piezoelectric catalysis and 25.4 times higher than that of single photocatalysis. The significant enhancement of photocatalytic activity can be attributed to the synergistic coupling of the surface plasmon resonance (SPR) effect and the piezoelectric effect. Full article
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12 pages, 4872 KiB  
Article
The Impact of Ambient Temperature on Electrothermal Characteristics in Stacked Nanosheet Transistors with Multiple Lateral Stacks
Nanomaterials 2023, 13(22), 2971; https://doi.org/10.3390/nano13222971 - 18 Nov 2023
Viewed by 704
Abstract
With characteristic size scaling down to the nanoscale range, the confined geometry exacerbates the self-heating effect (SHE) in nanoscale devices. In this paper, the impact of ambient temperature (Tamb) on the SHE in stacked nanosheet transistors is investigated. As the [...] Read more.
With characteristic size scaling down to the nanoscale range, the confined geometry exacerbates the self-heating effect (SHE) in nanoscale devices. In this paper, the impact of ambient temperature (Tamb) on the SHE in stacked nanosheet transistors is investigated. As the number of lateral stacks (Nstack) increases, the nanoscale devices show more severe thermal crosstalk issues, and the current performance between n- and p-type nanoscale transistors exhibits different degradation trends. To compare the effect of different Tamb ranges, the temperature coefficients of current per stack and threshold voltage are analyzed. As the Nstack increases from 4 to 32, it is verified that the zero-temperature coefficient bias point (VZTC) decreases significantly in p-type nanoscale devices when Tamb is above room temperature. This can be explained by the enhanced thermal crosstalk. Then, the gate length-dependent electrothermal characteristics with different Nstacks are investigated at various Tambs. To explore the origin of drain current variation, the temperature-dependent backscattering model is utilized to explain the variation. At last, the simulation results verify the impact of Tamb on the SHE. The study provides an effective design guide for stacked nanosheet transistors when considering multiple stacks in circuit applications. Full article
(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)
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23 pages, 3557 KiB  
Article
Polymeric Membranes Doped with Halloysite Nanotubes Imaged using Proton Microbeam Microscopy
Nanomaterials 2023, 13(22), 2970; https://doi.org/10.3390/nano13222970 - 18 Nov 2023
Viewed by 950
Abstract
Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, [...] Read more.
Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (µ-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages. Full article
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30 pages, 7860 KiB  
Article
Elaboration of Nanostructured Levan-Based Colloid System as a Biological Alternative with Antimicrobial Activity for Applications in the Management of Pathogenic Microorganisms
Nanomaterials 2023, 13(22), 2969; https://doi.org/10.3390/nano13222969 - 17 Nov 2023
Viewed by 871
Abstract
Considering the documented health benefits of bacterial exopolysaccharides (EPSs), specifically of bacterial levan (BL), including its intrinsic antimicrobial activity against certain pathogenic species, the current study concentrated on the development of active pharmaceutical ingredients (APIs) in the form of colloid systems (CoSs) containing [...] Read more.
Considering the documented health benefits of bacterial exopolysaccharides (EPSs), specifically of bacterial levan (BL), including its intrinsic antimicrobial activity against certain pathogenic species, the current study concentrated on the development of active pharmaceutical ingredients (APIs) in the form of colloid systems (CoSs) containing silver nanoparticles (AgNPs) employing in-house biosynthesized BL as a reducing and capping agent. The established protocol of fermentation conditions implicating two species of lactic acid bacteria (LAB), i.e., Streptococcus salivarius K12 and Leuconostoc mesenteroides DSM 20343, ensured a yield of up to 25.7 and 13.7 g L−1 of BL within 72 h, respectively. An analytical approach accomplished by Fourier-transform infrared (FT-IR) spectroscopy allowed for the verification of structural features attributed to biosynthesized BL. Furthermore, scanning electron microscopy (SEM) revealed the crystalline morphology of biosynthesized BL with a smooth and glossy surface and highly porous structure. Molecular weight (Mw) estimated by multi-detector size-exclusion chromatography (SEC) indicated that BL biosynthesized using S. salivarius K12 has an impressively high Mw, corresponding to 15.435 × 104 kilodaltons (kDa). In turn, BL isolated from L. mesenteroides DSM 20343 was found to have an Mw of only 26.6 kDa. Polydispersity index estimation (PD = Mw/Mn) of produced BL displayed a monodispersed molecule isolated from S. salivarius K12, corresponding to 1.08, while this was 2.17 for L. mesenteroides DSM 20343 isolate. The presence of fructose as the main backbone and, to a lesser extent, glucose and galactose as side chain molecules in EPS hydrolysates was supported by HPLC-RID detection. In producing CoS-BL@AgNPs within green biosynthesis, the presence of nanostructured objects with a size distribution from 12.67 ± 5.56 nm to 46.97 ± 20.23 was confirmed by SEM and energy-dispersive X-ray spectroscopy (EDX). The prominent inhibitory potency of elaborated CoS-BL@AgNPs against both reference test cultures, i.e., Pseudomonas aeruginosa, Escherichia coli, Enterobacter aerogenes, and Staphylococcus aureus and those of clinical origin with multi-drug resistance (MDR), was confirmed by disc and well diffusion tests and supported by the values of the minimum inhibitory and bactericidal concentrations. CoS-BL@AgNPs can be treated as APIs suitable for designing new antimicrobial agents and modifying therapies in controlling MDR pathogens. Full article
(This article belongs to the Special Issue Advances in Nanomedicine Biotechnologies)
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28 pages, 23357 KiB  
Review
Recent Development and Applications of Stretchable SERS Substrates
Nanomaterials 2023, 13(22), 2968; https://doi.org/10.3390/nano13222968 - 17 Nov 2023
Viewed by 963
Abstract
Surface-enhanced Raman scattering (SERS) is a cutting-edge technique for highly sensitive analysis of chemicals and molecules. Traditional SERS-active nanostructures are constructed on rigid substrates where the nanogaps providing hot-spots of Raman signals are fixed, and sample loading is unsatisfactory due to the unconformable [...] Read more.
Surface-enhanced Raman scattering (SERS) is a cutting-edge technique for highly sensitive analysis of chemicals and molecules. Traditional SERS-active nanostructures are constructed on rigid substrates where the nanogaps providing hot-spots of Raman signals are fixed, and sample loading is unsatisfactory due to the unconformable attachment of substrates on irregular sample surfaces. A flexible SERS substrate enables conformable sample loading and, thus, highly sensitive Raman detection but still with limited detection capabilities. Stretchable SERS substrates with flexible sample loading structures and controllable hot-spot size provide a new strategy for improving the sample loading efficiency and SERS detection sensitivity. This review summarizes and discusses recent development and applications of the newly conceptual stretchable SERS substrates. A roadmap of the development of SERS substrates is reviewed, and fabrication techniques of stretchable SERS substrates are summarized, followed by an exhibition of the applications of these stretchable SERS substrates. Finally, challenges and perspectives of the stretchable SERS substrates are presented. This review provides an overview of the development of SERS substrates and sheds light on the design, fabrication, and application of stretchable SERS systems. Full article
(This article belongs to the Special Issue Advances in Nano-Enhanced Thermal Functional Materials)
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32 pages, 6120 KiB  
Article
Nanoparticles of the Perovskite-Structure CaTiO3 System: The Synthesis, Characterization, and Evaluation of Its Photocatalytic Capacity to Degrade Emerging Pollutants
Nanomaterials 2023, 13(22), 2967; https://doi.org/10.3390/nano13222967 - 17 Nov 2023
Viewed by 774
Abstract
In this research work, the photocatalytic capacity shown by the nanoparticles of the CaTiO3 system was evaluated to degrade two pollutants of emerging concern, namely methyl orange (MO)—considered an organic contaminating substance of the textile industry that is non-biodegradable when dissolved in [...] Read more.
In this research work, the photocatalytic capacity shown by the nanoparticles of the CaTiO3 system was evaluated to degrade two pollutants of emerging concern, namely methyl orange (MO)—considered an organic contaminating substance of the textile industry that is non-biodegradable when dissolved in water—and levofloxacin (LVF), an antibiotic widely used in the treatment of infectious diseases that is released mostly to the environment in its original chemical form. The synthesis process used to obtain these powders was the polymeric precursor method (Pechini), at a temperature of 700 °C for 6 h. The characterization of the obtained oxide nanoparticles of interest revealed the presence of a majority perovskite-type phase with an orthorhombic Pbnm structure and a minority rutile-type TiO2 phase, with a P42/mnm structure and a primary particle size <100nm. The adsorption–desorption isotherms of the synthesized solids had H3-type hysteresis loops, characteristic of mesoporous solids, with a BET surface area of 10.01m2/g. The Raman and FTIR spectroscopy results made it possible to identify the characteristic vibrations of the synthesized system and the characteristic deformations of the perovskite structure, reiterating the results obtained from the XRD analysis. Furthermore, a bandgap energy of ~3.4eV and characteristic emissions in the violet (437 nm/2.8 eV) and orange (611 nm/2.03 eV) were determined for excitation lengths of 250 nm and 325 nm, respectively, showing that these systems have a strong emission in the visible light region and allowing their use in photocatalytic activity to be potentialized. The powders obtained were studied for their photocatalytic capacity to degrade methyl orange (MO) and levofloxacin (LVF), dissolved in water. To quantify the coloring concentration, UV–visible spectroscopy was used considering the variation in the intensity of the characteristic of the greatest absorption, which correlated with the change in the concentration of the contaminant in the solution. The results showed that after irradiation with ultraviolet light, the degradation of the contaminants MO and LVF was 79.4% and 98.1% with concentrations of 5 g/L and 10 g/L, respectively. Full article
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26 pages, 3595 KiB  
Review
A Comprehensive Review on Electrocatalytic Applications of 2D Metallenes
Nanomaterials 2023, 13(22), 2966; https://doi.org/10.3390/nano13222966 - 17 Nov 2023
Cited by 1 | Viewed by 769
Abstract
This review introduces metallenes, a cutting-edge form of atomically thin two-dimensional (2D) metals, gaining attention in energy and catalysis. Their unique physicochemical and electronic properties make them promising for applications like catalysis. Metallenes stand out due to their abundance of under-coordinated metal atoms, [...] Read more.
This review introduces metallenes, a cutting-edge form of atomically thin two-dimensional (2D) metals, gaining attention in energy and catalysis. Their unique physicochemical and electronic properties make them promising for applications like catalysis. Metallenes stand out due to their abundance of under-coordinated metal atoms, enhancing the catalytic potential by improving atomic utilization and intrinsic activity. This review explores the utility of 2D metals as electrocatalysts in sustainable energy conversion, focusing on the Oxygen Evolution Reaction, Oxygen Reduction Reaction, Fuel Oxidation Reaction, and Carbon Dioxide Reduction Reaction. Aimed at researchers in nanomaterials and energy, the review is a comprehensive resource for unlocking the potential of 2D metals in creating a sustainable energy landscape. Full article
(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)
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24 pages, 8933 KiB  
Article
A Commercial Clay-Based Material as a Carrier for Targeted Lysozyme Delivery in Animal Feed
Nanomaterials 2023, 13(22), 2965; https://doi.org/10.3390/nano13222965 - 17 Nov 2023
Viewed by 534
Abstract
The controlled supply of bioactive molecules is a subject of debate in animal nutrition. The release of bioactive molecules in the target organ, in this case the intestine, results in improved feed, as well as having a lower environmental impact. However, the degradation [...] Read more.
The controlled supply of bioactive molecules is a subject of debate in animal nutrition. The release of bioactive molecules in the target organ, in this case the intestine, results in improved feed, as well as having a lower environmental impact. However, the degradation of bioactive molecules’ in transit in the gastrointestinal passage is still an unresolved issue. This paper discusses the feasibility of a simple and cost-effective procedure to bypass the degradation problem. A solid/liquid adsorption procedure was applied, and the operating parameters (pH, reaction time, and LY initial concentration) were studied. Lysozyme is used in this work as a representative bioactive molecule, while Adsorbo®, a commercial mixture of clay minerals and zeolites which meets current feed regulations, is used as the carrier. A maximum LY loading of 32 mgLY/gAD (LY(32)-AD) was obtained, with fixing pH in the range 7.5–8, initial LY content at 37.5 mgLY/gAD, and reaction time at 30 min. A full characterisation of the hybrid organoclay highlighted that LY molecules were homogeneously spread on the carrier’s surface, where the LY–carrier interaction was mainly due to charge interaction. Preliminary release tests performed on the LY(32)-AD synthesised sample showed a higher releasing capacity, raising the pH from 3 to 7. In addition, a preliminary Trolox equivalent antioxidant capacity (TEAC) assay showed an antioxidant capacity for the LY of 1.47 ± 0.18 µmol TroloxEq/g with an inhibition percentage of 33.20 ± 3.94%. Full article
(This article belongs to the Section Nanocomposite Materials)
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16 pages, 5829 KiB  
Article
Electrostatic Self-Assembled Synthesis of Amorphous/Crystalline g-C3N4 Homo-Junction for Efficient Photocatalytic H2 Production with Simultaneous Antibiotic Degradation
Nanomaterials 2023, 13(22), 2964; https://doi.org/10.3390/nano13222964 - 17 Nov 2023
Cited by 1 | Viewed by 585
Abstract
g-C3N4 has been regarded as a promising photocatalyst for photo-reforming antibiotics for H2 production but still suffers from its high charge recombination, which has been proven to be solvable by constructing a g-C3N4 homo-junction. However, those [...] Read more.
g-C3N4 has been regarded as a promising photocatalyst for photo-reforming antibiotics for H2 production but still suffers from its high charge recombination, which has been proven to be solvable by constructing a g-C3N4 homo-junction. However, those reported methods based on uncontrollable calcination for preparing a g-C3N4 homo-junction are difficult to reproduce. Herein, an amorphous/crystalline g-C3N4 homo-junction (ACN/CCN) was successfully synthesized via the electrostatic self-assembly attachment of negatively charged crystalline g-C3N4 nanorods (CCN) on positively charged amorphous g-C3N4 sheets (ACN). All the ACN/CCN samples displayed much higher photo-reforming of antibiotics for H2 production ability than that of pristine ACN and CCN. In particular, ACN/CCN-2 with the optimal ratio exhibited the best photocatalytic performance, with a H2 evolution rate of 162.5 μmol·g−1·h−1 and simultaneous consecutive ciprofloxacin (CIP) degradation under light irradiation for 4 h. The UV–vis diffuse reflectance spectra (DRS), photoluminescence (PL), and electrochemical results revealed that a homo-junction is formed in ACN/CCN due to the difference in the band arrangement of ACN and CCN, which effectively suppressed the charge recombination and then led to those above significantly enhanced photocatalytic activity. Moreover, H2 was generated from the water reduction reaction with a photogenerated electron (e), and CIP was degraded via a photogenerated hole (h+). ACN/CCN exhibited adequate photostability and reusability for photocatalytic H2 production with simultaneous CIP degradation. This work provides a new idea for rationally designing and preparing homo-junction photocatalysts to achieve the dual purpose of chemical energy production and environmental treatment. Full article
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12 pages, 2306 KiB  
Article
Conversion of Natural Biowaste into Energy Storage Materials and Estimation of Discharge Capacity through Transfer Learning in Li-Ion Batteries
Nanomaterials 2023, 13(22), 2963; https://doi.org/10.3390/nano13222963 - 16 Nov 2023
Viewed by 707
Abstract
To simultaneously reduce the cost of environmental treatment of discarded food waste and the cost of energy storage materials, research on biowaste conversion into energy materials is ongoing. This work employs a solid-state thermally assisted synthesis method, transforming natural eggshell membranes (NEM) into [...] Read more.
To simultaneously reduce the cost of environmental treatment of discarded food waste and the cost of energy storage materials, research on biowaste conversion into energy materials is ongoing. This work employs a solid-state thermally assisted synthesis method, transforming natural eggshell membranes (NEM) into nitrogen-doped carbon. The resulting NEM-coated LFP (NEM@LFP) exhibits enhanced electrical and ionic conductivity that can promote the mobility of electrons and Li-ions on the surface of LFP. To identify the optimal synthesis temperature, the synthesis temperature is set to 600, 700, and 800 °C. The NEM@LFP synthesized at 700 °C (NEM 700@LFP) contains the most pyrrolic nitrogen and has the highest ionic and electrical conductivity. When compared to bare LFP, the specific discharge capacity of the material is increased by approximately 16.6% at a current rate of 0.1 C for 50 cycles. In addition, we introduce innovative data-driven experiments to observe trends and estimate the discharge capacity under various temperatures and cycles. These data-driven results corroborate and support our experimental analysis, highlighting the accuracy of our approach. Our work not only contributes to reducing environmental waste but also advances the development of efficient and eco-friendly energy storage materials. Full article
(This article belongs to the Special Issue Nanomaterials for Ion Battery Applications II)
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18 pages, 14205 KiB  
Article
A Carbon Nanocomposite Material Used in the Physical Modelling of the Overburden Subsidence Process
Nanomaterials 2023, 13(22), 2962; https://doi.org/10.3390/nano13222962 - 16 Nov 2023
Viewed by 501
Abstract
Carbon nanomaterial is widely used in structural health monitoring due to the advantage of sensitivity and good mechanical properties. This study presents a novel approach employing carbon nanocomposite materials (CNMs) to characterize deformation and damage evolution in physical modelling. As the primary measurement [...] Read more.
Carbon nanomaterial is widely used in structural health monitoring due to the advantage of sensitivity and good mechanical properties. This study presents a novel approach employing carbon nanocomposite materials (CNMs) to characterize deformation and damage evolution in physical modelling. As the primary measurement method, the CNM is used to investigate the deformation characteristics of a 200–400 m thick sandstone bed at a 1 km deep longwall mine. The sandstone unit is identified as an ultra-thick key stratum (UTKS), with its thicknesses varying across different mining panels of the UTKS. The results of CNM monitoring show that the UTKS remains stable even after a consecutive excavation of 900 m in width. This stability impedes the upward propagation of overlying strata failure, leading to minimal surface subsidence. The study demonstrates the huge potential of CNM in the mining area, which can be useful for investigating material damage in physical modelling studies. The findings suggest that the cumulative extraction width in individual mining areas of the mine should be controlled to avoid a sudden collapse of the UTKS, and that special attention should be paid to where the UTKS’s thickness changes substantially. The substantial variation in UTKS thickness significantly impacts the pattern of overburden subsidence. Full article
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14 pages, 4110 KiB  
Article
Hierarchically Porous Carbon Networks Derived from Chitosan for High-Performance Electrochemical Double-Layer Capacitors
Nanomaterials 2023, 13(22), 2961; https://doi.org/10.3390/nano13222961 - 16 Nov 2023
Viewed by 702
Abstract
Activated carbon (AC) compounds derived from biomass precursors have garnered significant attention as electrode materials in electric double-layer capacitors (EDLCs) due to their ready availability, cost-effectiveness, and potential for mass production. However, the accessibility of their active sites in electrochemistry has not been [...] Read more.
Activated carbon (AC) compounds derived from biomass precursors have garnered significant attention as electrode materials in electric double-layer capacitors (EDLCs) due to their ready availability, cost-effectiveness, and potential for mass production. However, the accessibility of their active sites in electrochemistry has not been investigated in detail. In this study, we synthesized two novel macro/micro-porous carbon structures prepared from a chitosan precursor using an acid/potassium hydroxide activation process and then examined the relationship between their textural characteristics and capacitance as EDLCs. The material characterizations showed that the ACs, prepared through different activation processes, differed in porosity, with distinctive variations in particle shape. The sample activated at 800 °C (Act-chitosan) was characterized by plate-shaped particles, a specific surface area of 4128 m2/g, and a pore volume of 1.87 cm3/g. Assessment of the electrochemical characteristics of Act-chitosan showed its remarkable capacitance of 183.5 F/g at a scan rate of 5 mV/s, and it maintained exceptional cyclic stability even after 10,000 cycles. The improved electrochemical performance of both chitosan-derived carbon structures could thus be attributed to their large, well-developed active sites within pores < 2 nm, despite the fact that interconnected macro-porous particles can enhance ion accessibility on electrodes. Our findings provide a basis for the fabrication of biomass-based materials with promising applications in electrochemical energy storage systems. Full article
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11 pages, 5536 KiB  
Communication
Preparation and Mechanical Properties of UV-Curable Epoxy Acrylate/Modified Aramid Nanofiber Nanocomposite Films
Nanomaterials 2023, 13(22), 2960; https://doi.org/10.3390/nano13222960 - 16 Nov 2023
Viewed by 697
Abstract
In order to enhance the mechanical properties of UV-curable epoxy acrylate (EA)-based coatings, 3-(trimethoxysilyl)propyl methacrylate modified aramid nanofibers (T-ANFs) were synthesized and used as nanofillers to prepare EA/T-ANF nanocomposite films. The morphology of T-ANFs was characterized by transmission electron microscopy. The chemical structure [...] Read more.
In order to enhance the mechanical properties of UV-curable epoxy acrylate (EA)-based coatings, 3-(trimethoxysilyl)propyl methacrylate modified aramid nanofibers (T-ANFs) were synthesized and used as nanofillers to prepare EA/T-ANF nanocomposite films. The morphology of T-ANFs was characterized by transmission electron microscopy. The chemical structure of T-ANFs was analyzed via infrared spectroscopy, confirming successful grafting of methyl methacryloyloxy groups onto the surface of aramid nanofibers (ANFs). Real-time infrared spectroscopy was employed to investigate the influence of ANFs and T-ANFs on the photopolymerization kinetics of the EA film. The results revealed that the addition of ANFs and T-ANFs led to a decrease in the photopolymerization rate during the initial stage but had little impact on the final double bond conversion, with all samples exhibiting a conversion rate of over 83%. The incorporation of ANFs improved the tensile strength of the films while significantly reducing their Young’s modulus. In contrast, the addition of T-ANFs led to a substantial increase in both tensile stress and Young’s modulus of the films. For instance, the tensile strength and Young’s modulus of the 0.1 wt% of T-ANF film increased by 52.7% and 41.6%, respectively, compared to the pure EA film. To further study the dispersion morphology and reinforcement mechanism, the cross-sectional morphology of the films was characterized by scanning electron microscopy. Full article
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17 pages, 4133 KiB  
Article
Enhanced Visible Light-Driven Photocatalytic Water-Splitting Reaction of Titanate Nanotubes Sensitised with Ru(II) Bipyridyl Complex
Nanomaterials 2023, 13(22), 2959; https://doi.org/10.3390/nano13222959 - 16 Nov 2023
Viewed by 693
Abstract
The ion exchange of Na+ cations was used to photosensitise titanates nanotubes (Ti-NTs) with tris(2,2’-bipyridine)ruthenium(II) cations (Ru(bpy)32+); this yielded a light-sensitised Ti-NTs composite denoted as (Ru(bpy)3)Ti-NTs, exhibiting the characteristic absorption of Ru(bpy)32+ in visible light. [...] Read more.
The ion exchange of Na+ cations was used to photosensitise titanates nanotubes (Ti-NTs) with tris(2,2’-bipyridine)ruthenium(II) cations (Ru(bpy)32+); this yielded a light-sensitised Ti-NTs composite denoted as (Ru(bpy)3)Ti-NTs, exhibiting the characteristic absorption of Ru(bpy)32+ in visible light. Incident photon-to-current efficiency (IPCE) measurements and the photocatalytic reduction of methyl viologen reaction confirmed that in the photosensitisation of the (Ru(bpy)3)Ti-NTs composite, charge transfer and charge separation occur upon excitation by ultraviolet and visible light irradiation. The photocatalytic potential of titanate nanotubes was tested in the water-splitting reaction and the H2 evolution reaction using a sacrificial agent and showed photocatalytic activity under various light sources, including xenon–mercury lamp, simulated sunlight, and visible light. Notably, in the conditions of the H2 evolution reaction when (Ru(bpy)3)Ti-NTs were submitted to simulated sunlight, they exceeded the photocatalytic activity of pristine Ti-NTs and TiO2 by a factor of 3 and 3.5 times, respectively. Also, (Ru(bpy)3)Ti-NTs achieved the photocatalytic water-splitting reaction under simulated sunlight and visible light, producing, after 4 h, 199 and 282 μmol×Hgcat−1. These results confirm the effective electron transfer of Ru(bpy)3 to titanate nanotubes. The stability of the photocatalyst was evaluated by a reuse test of four cycles of 24 h reactions without considerable loss of catalytic activity and crystallinity. Full article
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5 pages, 205 KiB  
Editorial
Nanocatalysis for Environmental Protection, Energy, and Green Chemistry
Nanomaterials 2023, 13(22), 2958; https://doi.org/10.3390/nano13222958 - 16 Nov 2023
Viewed by 557
Abstract
Nowadays, nanoscience and nanotechnology depict cutting-edge areas of modern science and technology across an array of applications, including heterogeneous catalysis [...] Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
14 pages, 327 KiB  
Article
An ICP-MS-Based Analytical Strategy for Assessing Compliance with the Ban of E 171 as a Food Additive on the EU Market
Nanomaterials 2023, 13(22), 2957; https://doi.org/10.3390/nano13222957 - 15 Nov 2023
Viewed by 717
Abstract
A method was developed for the determination of total titanium in food and food supplements by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid digestion of samples. Five food supplements, including one certified reference material, and 15 food products were used for [...] Read more.
A method was developed for the determination of total titanium in food and food supplements by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid digestion of samples. Five food supplements, including one certified reference material, and 15 food products were used for method development. Key factors affecting the analytical results, such as the composition of the acid mixture for sample digestion and the bias from spectral interferences on the different titanium isotopes, were investigated. Resolution of interferences was achieved by ICP-MS/MS with ammonia adduct formation and viable conditions for control laboratories equipped with standard quadrupole instruments were identified. The method was successfully validated and enables rapid screening of samples subject to confirmatory analysis for the presence of TiO2 particles. For the latter, single-particle ICP-MS (spICP-MS) analysis after chemical extraction of the particles was used. The two methods establish a viable analytical strategy for assessing the absence of titania particles in food products on the EU market following the E 171 ban as a food additive. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
11 pages, 4209 KiB  
Article
Lasing Emission from Soft Photonic Crystals for Pressure and Position Sensing
Nanomaterials 2023, 13(22), 2956; https://doi.org/10.3390/nano13222956 - 15 Nov 2023
Viewed by 652
Abstract
In this report, we introduce a 1D photonic crystal (PhC) nanocavity with waveguide-like strain amplifiers within a soft polydimethylsiloxane substrate, presenting it as a potential candidate for highly sensitive pressure and position optical sensors. Due to its substantial optical wavelength response to uniform [...] Read more.
In this report, we introduce a 1D photonic crystal (PhC) nanocavity with waveguide-like strain amplifiers within a soft polydimethylsiloxane substrate, presenting it as a potential candidate for highly sensitive pressure and position optical sensors. Due to its substantial optical wavelength response to uniform pressure, laser emission from this nanocavity enables the detection of a minimum applied uniform pressure of 1.6‰ in experiments. Based on this feature, we further studied and elucidated the distinct behaviors in wavelength shifts when applying localized pressure at various positions relative to the PhC nanocavity. In experiments, by mapping wavelength shifts of the PhC nanolaser under localized pressure applied using a micro-tip at different positions, we demonstrate the nanocavity’s capability to detect minute position differences, with position-dependent minimum resolutions ranging from tens to hundreds of micrometers. Furthermore, we also propose and validate the feasibility of employing the strain amplifier as an effective waveguide for extracting the sensing signal from the nanocavity. This approach achieves a 64% unidirectional coupling efficiency for leading out the sensing signal to a specific strain amplifier. We believe these findings pave the way for creating a highly sensitive position-sensing module that can accurately identify localized pressure in a planar space. Full article
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12 pages, 2852 KiB  
Article
A Nanograss Boron and Nitrogen Co-Doped Diamond Sensor Produced via High-Temperature Annealing for the Detection of Cadmium Ions
Nanomaterials 2023, 13(22), 2955; https://doi.org/10.3390/nano13222955 - 15 Nov 2023
Viewed by 587
Abstract
The high-performance determination of heavy metal ions (Cd2+) in water sources is significant for the protection of public health and safety. We have developed a novel sensor of nanograss boron and nitrogen co-doped diamond (NGBND) to detect Cd2+ using a [...] Read more.
The high-performance determination of heavy metal ions (Cd2+) in water sources is significant for the protection of public health and safety. We have developed a novel sensor of nanograss boron and nitrogen co-doped diamond (NGBND) to detect Cd2+ using a simple method without any masks or reactive ion etching. The NGBND electrode is constructed based on the co-doped diamond growth mode and the removal of the non-diamond carbon (NDC) from the NGBND/NDC composite. Both the enlarged surface area and enhanced electrochemical performance of the NGBND film are achievable. Scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse anodic stripping voltammetry (DPASV) were used to characterize the NGBND electrodes. Furthermore, we used a finite element numerical method to research the current density near the tip of NGBND. The NGBND sensor exhibits significant advantages for detecting trace Cd2+ via DPASV. A broad linear range of 1 to 100 μg L−1 with a low detection limit of 0.28 μg L−1 was achieved. The successful application of this Cd2+ sensor indicates considerable promise for the sensitive detection of heavy metal ions. Full article
(This article belongs to the Special Issue Carbon Nanomaterials for Electrochemical Applications)
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13 pages, 7264 KiB  
Article
Construction of Binary RGO/TiO2 Fibrous Membranes with Enhanced Mechanical Properties for E. coli Inactivation
Nanomaterials 2023, 13(22), 2954; https://doi.org/10.3390/nano13222954 - 15 Nov 2023
Viewed by 513
Abstract
For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiO2 membranes with heterogeneous structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. [...] Read more.
For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiO2 membranes with heterogeneous structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. In the binary nanocomposites, RGO was tightly adhered to TiO2 fibers and by simply adjusting the loading of RGO, the strength and modulus of the fibrous membranes were improved. Notably, the RGO-permeated TiO2 fibers exhibited 1.41 MPa in tensile strength and 140.02 MPa in Young’s modulus, which were 705% and 343% of the original TiO2 fibers, respectively. Benefiting from the enhanced light response and the homogeneous and compact heterogeneous structure, the synthesized RGO/TiO2 membranes displayed good antibacterial performance with a photocatalytic inactivation rate of 6 log against E. coli within 60 min. This study offers a highly efficient alternative to inactivate E. coli for the synthesis of TiO2-based membranes. Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
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15 pages, 14385 KiB  
Article
3D-Printed Piezoelectret Based on Foamed Polylactic Acid for Energy-Harvesting and Sensing Applications
Nanomaterials 2023, 13(22), 2953; https://doi.org/10.3390/nano13222953 - 15 Nov 2023
Viewed by 768
Abstract
Poly(lactic) acid (PLA) is a bio-compatible polymer widely used in additive manufacturing, and in the form of cellular foam it shows excellent mechanical and piezoelectric properties. This type of structure can be easily 3D-printed by Fusion Deposition Modelling (FDM) with commercially available composite [...] Read more.
Poly(lactic) acid (PLA) is a bio-compatible polymer widely used in additive manufacturing, and in the form of cellular foam it shows excellent mechanical and piezoelectric properties. This type of structure can be easily 3D-printed by Fusion Deposition Modelling (FDM) with commercially available composite filaments. In this work, we present mechanical and electrical investigations on 3D-printed low-cost and eco-friendly foamed PLA. The cellular microstructure and the foaming degree were tuned by varying extrusion temperature and flowrate. The maximum surface potential and charge stability of disk samples were found in correspondence of extrusion temperature between 230 and 240 °C with a flowrate of 53–44% when charging on a heated bed at 85 °C. The cells’ morphology and correlated mechanical properties were analyzed and the measured piezoelectric d33 coefficient was found to be 212 pC/N. These findings show the importance of printing parameters and thermal treatment during the charging process in order to obtain the highest charge storage, stability and material flexibility. These results suggest that 3D-printed cellular PLA is a promising sustainable material for sensing and energy-harvesting applications. Full article
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17 pages, 6016 KiB  
Article
Experimental Study on Thermal Conductivity of Water-Based Magnetic Fluid Loaded with Different Nanoparticles
Nanomaterials 2023, 13(22), 2952; https://doi.org/10.3390/nano13222952 - 15 Nov 2023
Viewed by 613
Abstract
Magnetic fluids, a new type of energy transfer fluid with tunable properties, have garnered significant interest from researchers worldwide. Hybrid magnetic fluids prepared by adding different types of nanoparticles exhibit superior thermophysical properties and functional characteristics. In this paper, we prepared a water-based [...] Read more.
Magnetic fluids, a new type of energy transfer fluid with tunable properties, have garnered significant interest from researchers worldwide. Hybrid magnetic fluids prepared by adding different types of nanoparticles exhibit superior thermophysical properties and functional characteristics. In this paper, we prepared a water-based magnetic fluid loaded with multi-walled carbon nanotubes (MCNTs), silver (Ag), and copper (Cu) to enhance thermal conductivity. Using a transient double hot-wire method, we designed and built an experimental measurement system for the thermal conductivity of magnetic fluids with an average measurement error of less than 5%. We studied the thermal conductivity of hybrid magnetic fluids under different conditions and evaluated the advantages and disadvantages of various models, including the Maxwell model, H&C model, Tim model, Y&C model, and Evans model. Our results show that MF+MCNTs, MF+Ag, and MF+Cu nanofluids can all improve the thermal conductivity of the carrier fluid, with MF+MCNTs exhibiting the best improvement effect of 10.93%. Among the five models evaluated, the Evans model had the best predictive effect with a deviation range within 5%. This work provides theoretical and practical reference for enhancing the thermal conductivity of magnetic fluids and provides a more accurate theoretical model for calculating the thermal conductivity of hybrid magnetic fluids. Full article
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16 pages, 4910 KiB  
Article
Comparative Study of Different Pretreatment and Combustion Methods on the Grindability of Rice-Husk-Based SiO2
Nanomaterials 2023, 13(22), 2951; https://doi.org/10.3390/nano13222951 - 15 Nov 2023
Viewed by 545
Abstract
The rice husk (RH) combustion pretreatment method plays a crucial role in the extraction of nanoscale SiO2 from RH as a silicon source. This study examined the effects of diverse pretreatment methods and combustion temperatures on the particle size distribution of nanoscale [...] Read more.
The rice husk (RH) combustion pretreatment method plays a crucial role in the extraction of nanoscale SiO2 from RH as a silicon source. This study examined the effects of diverse pretreatment methods and combustion temperatures on the particle size distribution of nanoscale high-purity amorphous SiO2 extracted from rice husk ash (RHA) post RH combustion. The experiment was structured using the Taguchi method, employing an L9 (21 × 33) orthogonal mixing table. The median diameter (D50) served as the output response parameter, with the drying method (A), combustion temperature (B), torrefaction temperature (C), and pretreatment method (D) as the input parameters. The results showed the torrefaction temperature (C) as being the predominant factor affecting the D50, which decreased with an increasing torrefaction temperature (C). The optimal parameter combination was identified as A2B2C3D2. The verification test revealed that roasting could improve the abrasiveness of Rh-based silica and reduce the average particle size. Torrefaction at medium temperatures might narrow the size distribution range of RHA-SiO2. We discovered that the purity of silica increased with an increasing roasting temperature by evaluating the concentration of silica in the sample. The production of RHA with silica concentrations up to 92.3% was investigated. X-ray diffraction analysis affirmed that SiO2’s crystal structure remained unaltered across different treatment methods, consistently presenting as amorphous. These results provide a reference for extracting high-value products through RH combustion. Full article
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