Nanomaterials

13 pages, 5136 KiB

Open AccessArticle

Thermal Decomposition of Core–Shell-Structured RDX@AlH₃, HMX@AlH₃, and CL-20@AlH₃ Nanoparticles: Reactive Molecular Dynamics Simulations

by Zijian Sun, Lei Yang, Hui Li, Mengyun Mei, Lixin Ye, Jiake Fan and Weihua Zhu

Nanomaterials 2024, 14(22), 1859; https://doi.org/10.3390/nano14221859 - 20 Nov 2024

Viewed by 1021

Abstract

The reactive molecular dynamics method was employed to examine the thermal decomposition process of aluminized hydride (AlH₃) containing explosive nanoparticles with a core–shell structure under high temperature. The core was composed of the explosives RDX, HMX, and CL-20, while the shell [...] Read more.

The reactive molecular dynamics method was employed to examine the thermal decomposition process of aluminized hydride (AlH₃) containing explosive nanoparticles with a core–shell structure under high temperature. The core was composed of the explosives RDX, HMX, and CL-20, while the shell was composed of AlH₃. It was demonstrated that the CL-20@AlH₃ NPs decomposed at a faster rate than the other NPs, and elevated temperatures could accelerate the initial decomposition of the explosive molecules. The incorporation of aluminized hydride shells did not change the initial decomposition mechanism of the three explosives. The yields of the main products (NO, NO₂, N₂, H₂O, H₂, and CO₂) were investigated. There was a large number of solid aluminized clusters produced during the decomposition, mainly Al_mO_n and Al_mC_n clusters, together with Al_mN_n clusters dispersed in the Al_mO_n clusters. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Theory and Simulation of Nanostructures)

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(a) Models of RDX/HMX/CL-20@AlH3 NPs, (b) schematic diagram of aluminized hydride explosives with a core–shell structure. C, H, O, N, and Al atoms are represented by gray, white, red, blue, and pink balls, respectively. Full article ">Figure 2
Snapshots of the morphology of RDX@AlH3 NPs at 2400 K. Full article ">Figure 3
Evolution of the number of the total species in the three AlH3-containing explosives with time at (a) 2100, (b) 2400, (c) 2700, and (d) 3000 K. Peak values (e) and number (f) of total species as a function of temperature. Full article ">Figure 4
Time evolution of the products in the RDX@AlH3 NPs at 2100, 2400, 2700, and 3000 K. Full article ">Figure 5
Time evolution of the number of RDX, HMX, and CL-20 molecules at 2100, 2400, 2700, and 3000 K. Full article ">Figure 6
AlmOn clusters in RDX @AlH3 (a), HMX@AlH3 (b), and CL-20@AlH3 (c) NPs, and their basic unit (d). Full article ">Figure 7
AlmCn clusters in the RDX @AlH3 (a), HMX@AlH3 (b), and CL-20@AlH3 (c) NPs. Full article ">

15 pages, 3703 KiB

Open AccessArticle

Tuning Intermediate Band Solar Cell Efficiency: The Interplay of Electric Fields, Composition, Impurities, and Confinement

by Hassan Abboudi, Redouane En-nadir, Mohamed A. Basyooni-M. Kabatas, Ayoub El Baraka, Ilyass Ez-zejjari, Haddou El Ghazi and Ahmed Sali

Nanomaterials 2024, 14(22), 1858; https://doi.org/10.3390/nano14221858 - 20 Nov 2024

Viewed by 684

Abstract

In this study, we investigated the influence of structural parameters, including active region dimensions, electric field intensity, In-composition, impurity position, and potential profiles, on the energy levels, sub-gap transitions, and photovoltaic characteristics of a p-GaN/i-(In, Ga)N/GaN-n (p-QW-n) structure. The finite element method (FEM) [...] Read more.

In this study, we investigated the influence of structural parameters, including active region dimensions, electric field intensity, In-composition, impurity position, and potential profiles, on the energy levels, sub-gap transitions, and photovoltaic characteristics of a p-GaN/i-(In, Ga)N/GaN-n (p-QW-n) structure. The finite element method (FEM) has been used to solve numerically the Schrödinger equation. We found that particle and sub-gap energy levels are susceptible to well width, electric field, and impurity position. Particle energy decreases with increasing well size and electric field intensity, while impurity position affects energy based on proximity to the well center. Potential profile shapes, such as rectangular (RQW) and parabolic (PQW), also play a significant role, with PQW profiles providing stronger particle confinement. IB width increases with electric field intensity and saturates at higher In-content. Voc increases with field strength but decreases with In-content, and the parabolic profile yields higher efficiency than the rectangular one. Photovoltaic efficiency is improved with an appropriately oriented electric field and decreases with higher In-content and field intensity. These findings highlight the critical role of structural parameters in optimizing QW-IBSC performance. Full article

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16 pages, 4473 KiB

Open AccessArticle

Nano-Silver-Loaded Activated Carbon Material Derived from Waste Rice Noodles: Adsorption and Antibacterial Performance

by Guanzhi Ding, Guangzhi Qin, Wanying Ying, Pengyu Wang, Yang Yang, Chuanyang Tang, Qing Liu, Minghui Li, Ke Huang and Shuoping Chen

Nanomaterials 2024, 14(22), 1857; https://doi.org/10.3390/nano14221857 - 20 Nov 2024

Viewed by 857

Abstract

This study demonstrates, for the first time, the conversion of waste rice noodles (WRN) into a cost-effective, nano-silver-loaded activated carbon (Ag/AC) material capable of efficient adsorption and antibacterial activity. The fabrication process began with the conversion of WRN into hydrothermal carbon (HTC) via [...] Read more.

This study demonstrates, for the first time, the conversion of waste rice noodles (WRN) into a cost-effective, nano-silver-loaded activated carbon (Ag/AC) material capable of efficient adsorption and antibacterial activity. The fabrication process began with the conversion of WRN into hydrothermal carbon (HTC) via a hydrothermal method. Subsequently, the HTC was combined with silver nitrate (AgNO₃) and sodium hydroxide (NaOH), followed by activation through high-temperature calcination, during which AgNO₃ was reduced to nano-Ag and loaded onto the HTC-derived AC, resulting in a composite material with both excellent adsorption properties and antibacterial activity. The experimental results indicated that the incorporation of nano-Ag significantly enhanced the specific surface area of the Ag/AC composite and altered its pore size distribution characteristics. Under optimized preparation conditions, the obtained Ag/AC material exhibited a specific surface area of 2025.96 m²/g and an average pore size of 2.14 nm, demonstrating effective adsorption capabilities for the heavy metal Cr(VI). Under conditions of pH 2 and room temperature (293 K), the maximum equilibrium adsorption capacity for Cr(VI) reached 97.07 mg/g. The adsorption behavior of the resulting Ag/AC fitted the Freundlich adsorption isotherm and followed a pseudo-second-order kinetic model. Furthermore, the Ag/AC composite exhibited remarkable inhibitory effects against common pathogenic bacteria such as E. coli and S. aureus, achieving antibacterial rates of 100% and 81%, respectively, after a contact time of 4 h. These findings confirm the feasibility of utilizing the HTC method to process WRN and produce novel AC-based functional materials. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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30 pages, 6585 KiB

Open AccessReview

Recent Progress on Advanced Flexible Lithium Battery Materials and Fabrication Process

by Mi Zhou, Daohong Han, Xiangming Cui, Jingzhao Wang, Xin Chen, Jianan Wang, Shiyi Sun and Wei Yan

Nanomaterials 2024, 14(22), 1856; https://doi.org/10.3390/nano14221856 - 20 Nov 2024

Viewed by 1259

Abstract

Flexible energy storage devices have attracted wide attention as a key technology restricting the vigorous development of wearable electronic products. However, the practical application of flexible batteries faces great challenges, including the lack of good mechanical toughness of battery component materials and excellent [...] Read more.

Flexible energy storage devices have attracted wide attention as a key technology restricting the vigorous development of wearable electronic products. However, the practical application of flexible batteries faces great challenges, including the lack of good mechanical toughness of battery component materials and excellent adhesion between components, resulting in battery performance degradation or failure when subjected to different types of deformation. It is imperative to develop flexible batteries that can withstand deformation under different conditions and maintain stable battery performance. This paper reviews the latest research progress of flexible lithium batteries, from the research and development of new flexible battery materials, advanced preparation processes, and typical flexible structure design. First, the types of key component materials and corresponding modification technologies for flexible batteries are emphasized, mainly including carbon-based materials with flexibility, lithium anode materials, and solid-state electrolyte materials. In addition, the application of typical flexible structural designs (buckling, spiral, and origami) in flexible batteries is clarified, such as 3D printing and electrospinning, as well as advanced fabrication techniques commonly used in flexible materials and battery components. Finally, the limitations and coping strategies in the practical application of flexible lithium batteries are discussed, which provides new ideas for future research. Full article

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17 pages, 7201 KiB

Open AccessArticle

Thermal Performance Analysis of a Nonlinear Couple Stress Ternary Hybrid Nanofluid in a Channel: A Fractal–Fractional Approach

by Saqib Murtaza, Nidhal Becheikh, Ata Ur Rahman, Aceng Sambas, Chemseddine Maatki, Lioua Kolsi and Zubair Ahmad

Nanomaterials 2024, 14(22), 1855; https://doi.org/10.3390/nano14221855 - 20 Nov 2024

Cited by 1 | Viewed by 723

Abstract

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The [...] Read more.

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The use of nanofluids in technology and industry is steadily increasing due to their effective implementation. The improved thermophysical properties of nanofluids have a significant impact on their effectiveness in convection phenomena. The technology is not yet complete at this point; binary and ternary nanofluids are currently being used to improve the performance of conventional fluids. Therefore, this work aims to theoretically investigate the ternary nanofluid flow of a couple stress fluid in a vertical channel. A homogeneous suspension of alumina, cuprous oxide, and titania nanoparticles is formed by dispersing trihybridized nanoparticles in a base fluid (water). The effects of pressure gradient and viscous dissipation are also considered in the analysis. The classical ternary nanofluid model with couple stress was generalized using the fractal–fractional derivative (FFD) operator. The Crank–Nicolson technique helped to discretize the generalized model, which was then solved using computer tools. To investigate the properties of the fluid flow and the distribution of thermal energy in the fluid, numerical methods were used to calculate the solution, which was then plotted as a function of various physical factors. The graphical results show that at a volume fraction of 0.04 (corresponding to 4% of the base fluid), the heat transfer rate of the ternary nanofluid flow increases significantly compared to the binary and unary nanofluid flows. Full article

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56 pages, 5775 KiB

Open AccessReview

Gold Nanoparticles in Nanomedicine: Unique Properties and Therapeutic Potential

by Furkan Eker, Emir Akdaşçi, Hatice Duman, Mikhael Bechelany and Sercan Karav

Nanomaterials 2024, 14(22), 1854; https://doi.org/10.3390/nano14221854 - 20 Nov 2024

Cited by 2 | Viewed by 2604

Abstract

Gold nanoparticles (NPs) have demonstrated significance in several important fields, including drug delivery and anticancer research, due to their unique properties. Gold NPs possess significant optical characteristics that enhance their application in biosensor development for diagnosis, in photothermal and photodynamic therapies for anticancer [...] Read more.

Gold nanoparticles (NPs) have demonstrated significance in several important fields, including drug delivery and anticancer research, due to their unique properties. Gold NPs possess significant optical characteristics that enhance their application in biosensor development for diagnosis, in photothermal and photodynamic therapies for anticancer treatment, and in targeted drug delivery and bioimaging. The broad surface modification possibilities of gold NPs have been utilized in the delivery of various molecules, including nucleic acids, drugs, and proteins. Moreover, gold NPs possess strong localized surface plasmon resonance (LSPR) properties, facilitating their use in surface-enhanced Raman scattering for precise and efficient biomolecule detection. These optical properties are extensively utilized in anticancer research. Both photothermal and photodynamic therapies show significant results in anticancer treatments using gold NPs. Additionally, the properties of gold NPs demonstrate potential in other biological areas, particularly in antimicrobial activity. In addition to delivering antigens, peptides, and antibiotics to enhance antimicrobial activity, gold NPs can penetrate cell membranes and induce apoptosis through various intracellular mechanisms. Among other types of metal NPs, gold NPs show more tolerable toxicity capacity, supporting their application in wide-ranging areas. Gold NPs hold a special position in nanomaterial research, offering limited toxicity and unique properties. This review aims to address recently highlighted applications and the current status of gold NP research and to discuss their future in nanomedicine. Full article

(This article belongs to the Special Issue The Synthesis of Antibacterial Nanomaterials and Their Biomedical Applications)

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14 pages, 2614 KiB

Open AccessArticle

Synthesis and Characterization of Microcapsules as Fillers for Self-Healing Dental Composites

by Maria Amalia Tăut, Marioara Moldovan, Miuţa Filip, Ioan Petean, Codruţa Saroşi, Stanca Cuc, Adrian Catalin Taut, Ioan Ardelean, Viorica Lazăr and Sorin Claudiu Man

Nanomaterials 2024, 14(22), 1853; https://doi.org/10.3390/nano14221853 - 20 Nov 2024

Viewed by 760

Abstract

This article proposes the synthesis and characterization of (triethylene glycol dimethacrylate–N,N-dihydroxyethyl-p-toluidine) TEGDMA-DHEPT self-healing microcapsules for their inclusion in dental composite formulations. The obtaining method is the in situ emulsion polymerization of the (poly urea-formaldehyde) (PUF) coatings. The microcapsules were characterized by Fourier transform [...] Read more.

This article proposes the synthesis and characterization of (triethylene glycol dimethacrylate–N,N-dihydroxyethyl-p-toluidine) TEGDMA-DHEPT self-healing microcapsules for their inclusion in dental composite formulations. The obtaining method is the in situ emulsion polymerization of the (poly urea-formaldehyde) (PUF) coatings. The microcapsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), high-performance liquid chromatography (HPLC), and low-field nuclear magnetic resonance (NMR) techniques. The optimal formation of uniform microcapsules is achieved at a stirring speed of 800 rpm and centrifugation is no longer necessary. HPLC demonstrates that the microcapsules formed at 800 rpm show a better control of liquid release than the heterogeneous ones obtained at a lower stirring speed. The centrifuged samples have rounded shapes, with dimensions between 80 and 800 nm, while the non-centrifuged samples are more uniform, with a spherical shape and dimensions of approximately 800 nm. Full article

(This article belongs to the Section Biology and Medicines)

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Obtaining microcapsules via in situ polymerization in an oil-in-water (O/W) emulsion. Full article ">Figure 2
FTIR spectra of P2 and P3 samples. Full article ">Figure 3
Microstructural investigation of nanocapsules after synthesis: SEM images of samples P1 (a) and P2 (b). Microstructure accompanied by ultrastructure as revealed by AFM: samples P1 (a’) and P2 (b’). Topographic 3D profile is presented below each AFM image. Full article ">Figure 4
Nanocapsule diameter distribution for P1 and P2 samples. Full article ">Figure 5
Microstructural investigation of nanocapsules after centrifugation: SEM images of samples P3 (a) and P4 (b). Microstructure accompanied by ultrastructure as revealed by AFM: samples P3 (a’) and P4 (b’). Topographic 3D profile is presented below each AFM image. Full article ">Figure 6
HPLC chromatograms obtained for (a) TEGDMA standard, (b) sample P2 after 7 days and (c) sample P3 after 14 days. Full article ">Figure 7
(a) The normalized FID signals recorded immediately after a 90-degree radiofrequency pulse. The steep decay corresponds to the solid-like component, and the slow decay to the liquid component. (b) The relaxation time distributions in the case of two samples (P2, P3) extracted via the CPMG technique. The largest peak corresponds to the liquid component inside the nanocapsules, and the smaller peaks may be associated with restricted molecular mobility as in solid-like components. Full article ">

10 pages, 2327 KiB

Open AccessArticle

Electric Field-Enhanced SERS Detection Using MoS₂-Coated Patterned Si Substrate with Micro-Pyramid Pits

by Tsung-Shine Ko, Hsiang-Yu Hsieh, Chi Lee, Szu-Hung Chen, Wei-Chun Chen, Wei-Lin Wang, Yang-Wei Lin and Sean Wu

Nanomaterials 2024, 14(22), 1852; https://doi.org/10.3390/nano14221852 - 20 Nov 2024

Viewed by 766

Abstract

This study utilized semiconductor processing techniques to fabricate patterned silicon (Si) substrates with arrays of inverted pyramid-shaped micro-pits by etching. Molybdenum trioxide (MoO₃) was then deposited on these patterned Si substrates using a thermal evaporation system, followed by two-stage sulfurization in [...] Read more.

This study utilized semiconductor processing techniques to fabricate patterned silicon (Si) substrates with arrays of inverted pyramid-shaped micro-pits by etching. Molybdenum trioxide (MoO₃) was then deposited on these patterned Si substrates using a thermal evaporation system, followed by two-stage sulfurization in a high-temperature furnace to grow MoS₂ thin films consisting of only a few atomic layers. During the dropwise titration of Rhodamine 6G (R6G) solution, a longitudinal electric field was applied using a Keithley 2400 (Cleveland, OH, USA) source meter. Raman mapping revealed that under a 100 mV condition, the analyte R6G molecules were effectively confined within the pits. Due to its two-dimensional structure, MoS₂ provides a high surface area and supports a surface-enhanced Raman scattering (SERS) charge transfer mechanism. The SERS results demonstrated that the intensity in the pits of the few-layer MoS₂/patterned Si SERS substrate was approximately 274 times greater compared to planar Si, with a limit of detection reaching 10⁻⁵ M. The experimental results confirm that this method effectively resolves the issue of random distribution of analyte molecules during droplet evaporation, thereby enhancing detection sensitivity and stability. Full article

(This article belongs to the Special Issue Nanoscale Photonics and Metamaterials)

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(a) Lithography process flowchart. (b) Fabrication of the SERS substrate: Si substrate patterned with inverted pyramid pits, MoO3 deposition, sulfurization to MoS2, and Cu electrode deposition. (c) SERS measurement setup: Cu electrodes are connected to a Keithley 2400 source meter to apply a longitudinal electric field for R6G localization. Full article ">Figure 2
SEM images of (a) patterned Si, (b) MoO3 deposited on patterned Si, and (c) MoS2 formed on patterned Si. (d) Raman spectra of MoS2 on patterned Si (blue) and planar Si (red), showing characteristic MoS2 peaks. Full article ">Figure 3
(a) SERS spectra for MoS2/patterned Si, patterned Si, and planar Si substrates with 10−3 M R6G, showing enhanced signal for MoS2/patterned Si at 1362 cm−1. (b) SERS spectra of MoS2/patterned Si under different voltages, with optimal enhancement at 100 mV. Full article ">Figure 4
Raman mapping images of R6G molecules on MoS2/patterned Si SERS substrate under applied voltages: (a) 0 mV, (b) 50 mV, (c) 100 mV, and (d) 150 mV, overlaid with corresponding OM images. The color scale represents signal intensity, ranging from blue (low) to red (high). Optimal SERS enhancement and uniform localization of R6G molecules within the pits are observed at 100 mV, whereas lower or higher voltages result in diminished signal intensity and less effective molecule aggregation. Full article ">Figure 5
Raman mapping images of R6G on MoS2/patterned Si substrate at different concentrations: (a) 10−3 M, (b) 10−4 M, (c) 10−5 M, and (d) 10−6 M, overlaid with corresponding OM images. The signal intensity decreases as the concentration reduces, with strong and uniform signals observed at higher concentrations (10−3 M), while the signals are significantly weaker at lower concentrations, indicating the detection limit around 10−5 M. Full article ">

17 pages, 2840 KiB

Open AccessArticle

Green Synthesis of Al-ZnO Nanoparticles Using Cucumis maderaspatanus Plant Extracts: Analysis of Structural, Antioxidant, and Antibacterial Activities

by S. K. Johnsy Sugitha, R. Gladis Latha, Raja Venkatesan, Seong-Cheol Kim, Alexandre A. Vetcher and Mohammad Rashid Khan

Nanomaterials 2024, 14(22), 1851; https://doi.org/10.3390/nano14221851 - 20 Nov 2024

Viewed by 1020

Abstract

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and [...] Read more.

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and antimicrobial activity using some bacterial and fungal strains. These nanoparticles were analyzed using X-ray diffraction (XRD), ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and thermogravimetric analysis/differential thermal analysis (TG-DTA). The average crystalline size was determined to be 25 nm, as evidenced by the XRD analysis. In the UV-vis spectrum, the absorption band was observed around 351 nm. It was discovered that the Al-ZnO nanoparticles had a bandgap of 3.25 eV using the Tauc relation. Furthermore, by FTIR measurement, the presence of the OH group, C=C bending of the alkene group, and C=O stretching was confirmed. The SEM analysis revealed that the nanoparticles were distributed uniformly throughout the sample. The EDAX spectrum clearly confirmed the presence of Zn, Al, and O elements in the Al-ZnO nanoparticles. The TEM results also indicated that the green synthesized Al-ZnO nanoparticles displayed hexagonal shapes with an average size of 25 nm. The doping of aluminum may enhance the thermal stability of the ZnO by altering the crystal structure or phase composition. The observed changes in TG, DTA, and DTG curves reflect the impact of aluminum doping on the structural and thermal properties of ZnO nanoparticles. The antibacterial activity of the Al-ZnO nanoparticles using the agar diffusion method showed that the maximum zone of inhibition has been noticed against organisms of Gram-positive S. aureus compared with Gram-negative E. coli. Moreover, antifungal activity using the agar cup method showed that the maximum zone of inhibition was observed on Aspergilus flavus, followed by Candida albicans. Al-doping nanoparticles increases the number of charge carriers, which can enhance the generation of reactive oxygen species (ROS) under UV light exposure. These ROS are known to possess strong antimicrobial properties. Al-doping can improve the crystallinity of ZnO, resulting in a larger surface area that facilitates more interaction with microbial cells. The structural and biological characteristics of Al-ZnO nanoparticles might be responsible for the enhanced antibacterial activity exhibited in the antibacterial studies. Al-ZnO nanoparticles with Cucumis maderaspatanus leaf extract produced via the green synthesis methods have remarkable antioxidant activity by scavenging free radicals against DPPH radicals, according to these results. Full article

(This article belongs to the Special Issue Antimicrobial and Antioxidant Activity of Nanoparticles)

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14 pages, 578 KiB

Open AccessArticle

Effective Piecewise Mass Distributions for Optimal Energy Eigenvalues of a Particle in Low-Dimensional Heterojunctions

by Josep Batle, Orion Ciftja, Mahmoud Abdel-Aty, Mohamed Ahmed Hafez and Shawkat Alkhazaleh

Nanomaterials 2024, 14(22), 1850; https://doi.org/10.3390/nano14221850 - 20 Nov 2024

Viewed by 700

Abstract

Systems composed of several multi-layer compounds have been extremely useful in tailoring different quantum physical properties of nanomaterials. This is very much true when it comes to semiconductor materials and, in particular, to heterostructures and heterojunctions. The formalism of a position-dependent effective mass [...] Read more.

Systems composed of several multi-layer compounds have been extremely useful in tailoring different quantum physical properties of nanomaterials. This is very much true when it comes to semiconductor materials and, in particular, to heterostructures and heterojunctions. The formalism of a position-dependent effective mass has proved to be a very efficient tool in those cases where quantum wells emerge either in one or two dimensions. In this work, we use a variety of mathematical theorems, as well as numerical computations, to study different scenarios pertaining to choices of a specific piecewise constant effective mass for a particle that causes its energy eigenvalues to reach an extremum. These results are relevant when it comes to practical technological applications such as modifying the optical energy gap between the first excited state and the ground state energy of the system. At the end of our contribution, we also question the physical validity of some approximations for systems with particles that possess a position-dependent mass especially for those cases in which the mass distribution is divergent. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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17 pages, 5981 KiB

Open AccessArticle

Free-Standing Carbon Nanofiber Films with Supported Cobalt Phosphide Nanoparticles as Cathodes for Hydrogen Evolution Reaction in a Microbial Electrolysis Cell

by Gerard Pérez-Pi, Jorge Luque-Rueda, Pau Bosch-Jimenez, Eduard Borràs Camps and Sandra Martínez-Crespiera

Nanomaterials 2024, 14(22), 1849; https://doi.org/10.3390/nano14221849 - 19 Nov 2024

Viewed by 1356

Abstract

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H₂) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have [...] Read more.

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H₂) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have been prepared by means of an up-scalable electrospinning process followed by a thermal treatment under controlled conditions. The produced cobalt phosphide-supported CNF films show to be nanoporous (pore volume up to 0.33 cm³ g⁻¹) with a high surface area (up to 502 m² g⁻¹) and with a suitable catalyst mass loading (up to 0.49 mg cm⁻²). Values of overpotential less than 140 mV at 10 mA cm⁻² have been reached for the HER in alkaline media (1 M KOH), which demonstrates a high activity. The high electrical conductivity together with the mechanical stability of the free-standing CNF films allowed their direct use as cathodes in a MEC reactor, resulting in an exceptionally low voltage operation (0.75 V) with a current density demand of 5.4 A m⁻². This enabled the production of H₂ with an energy consumption below 30 kWh kg⁻¹ H₂, which is highly efficient. Full article

(This article belongs to the Special Issue Hydrogen Production and Evolution Based on Nanocatalysts)

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25 pages, 10477 KiB

Open AccessArticle

Portable Homemade Magnetic Hyperthermia Apparatus: Preliminary Results

by Teresa Castelo-Grande, Paulo A. Augusto, Lobinho Gomes, Eduardo Calvo and Domingos Barbosa

Nanomaterials 2024, 14(22), 1848; https://doi.org/10.3390/nano14221848 - 19 Nov 2024

Viewed by 974

Abstract

This study aims to describe and evaluate the performance of a new device for magnetic hyperthermia that can produce an alternating magnetic field with adjustable frequency without the need to change capacitors from the resonant bank, as required by other commercial devices. This [...] Read more.

This study aims to describe and evaluate the performance of a new device for magnetic hyperthermia that can produce an alternating magnetic field with adjustable frequency without the need to change capacitors from the resonant bank, as required by other commercial devices. This innovation, among others, is based on using a capacitator bank that dynamically adjusts the frequency. To validate the novel system, a series of experiments were conducted using commercial magnetic nanoparticles (MNPs) demonstrating the device’s effectiveness and allowing us to identify new challenges associated with the design of more powerful devices. A computational model was also used to validate the device and to allow us to determine the best system configuration. The results obtained are consistent with those from other studies using the same MNPs but with magnetic hyperthermia commercial equipment, confirming the good performance of the developed device (e.g., consistent SAR values between 1.37 and 10.80 W/gMNP were obtained, and experiments reaching temperatures above 43 °C were also obtained). This equipment offers additional advantages, including being economical, user-friendly, and portable. Full article

(This article belongs to the Special Issue New Insights into the Therapeutic Efficacy of Nanomaterials)

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28 pages, 1948 KiB

Open AccessReview

Nanomaterial-Enhanced Hybrid Disinfection: A Solution to Combat Multidrug-Resistant Bacteria and Antibiotic Resistance Genes in Wastewater

by Tapas Kumar Mandal

Nanomaterials 2024, 14(22), 1847; https://doi.org/10.3390/nano14221847 - 19 Nov 2024

Cited by 1 | Viewed by 1068

Abstract

This review explores the potential of nanomaterial-enhanced hybrid disinfection methods as effective strategies for addressing the growing challenge of multidrug-resistant (MDR) bacteria and antibiotic resistance genes (ARGs) in wastewater treatment. By integrating hybrid nanocomposites and nanomaterials, natural biocides such as terpenes, and ultrasonication, [...] Read more.

This review explores the potential of nanomaterial-enhanced hybrid disinfection methods as effective strategies for addressing the growing challenge of multidrug-resistant (MDR) bacteria and antibiotic resistance genes (ARGs) in wastewater treatment. By integrating hybrid nanocomposites and nanomaterials, natural biocides such as terpenes, and ultrasonication, this approach significantly enhances disinfection efficiency compared to conventional methods. The review highlights the mechanisms through which hybrid nanocomposites and nanomaterials generate reactive oxygen species (ROS) under blue LED irradiation, effectively disrupting MDR bacteria while improving the efficacy of natural biocides through synergistic interactions. Additionally, the review examines critical operational parameters—such as light intensity, catalyst dosage, and ultrasonication power—that optimize treatment outcomes and ensure the reusability of hybrid nanocomposites and other nanomaterials without significant loss of photocatalytic activity. Furthermore, this hybrid method shows promise in degrading ARGs, thereby addressing both microbial and genetic pollution. Overall, this review underscores the need for innovative wastewater treatment solutions that are efficient, sustainable, and scalable, contributing to the global fight against antimicrobial resistance. Full article

(This article belongs to the Special Issue Multifunctional Nanomaterials: Innovations in Energy Harvesting, Biological Applications, and Environmental Remediation)

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16 pages, 4681 KiB

Open AccessEditor’s ChoiceArticle

M-Doped (M = Zn, Mn, Ni) Co-MOF-Derived Transition Metal Oxide Nanosheets on Carbon Fibers for Energy Storage Applications

by Andrés González-Banciella, David Martinez-Diaz, Adrián de Hita, María Sánchez and Alejandro Ureña

Nanomaterials 2024, 14(22), 1846; https://doi.org/10.3390/nano14221846 - 19 Nov 2024

Viewed by 956

Abstract

Carbon fiber, with its strong mechanical properties and electrical conductivity, is ideal as a fiber electrode in wearable or structural energy storage devices. However, its energy storage capacity is limited, and coatings like transition metal oxides (TMOs) enhance its electrochemical performance. Metal–organic frameworks [...] Read more.

Carbon fiber, with its strong mechanical properties and electrical conductivity, is ideal as a fiber electrode in wearable or structural energy storage devices. However, its energy storage capacity is limited, and coatings like transition metal oxides (TMOs) enhance its electrochemical performance. Metal–organic frameworks (MOFs) are commonly used to grow TMOs on carbon fibers, increasing the surface area for better energy storage. Despite this, TMOs have limited electrical conductivity, so ion exchange is often used to dope them with additional cations, improving both conductivity and energy storage capacity. This study compares different ion-exchange cations in ZIF-L-derived TMO coatings on carbon fiber. Testing both supercapacitor and Li-ion battery applications, Ni-doped samples showed superior results, attributed to their higher exchange ratio with cobalt. As a supercapacitor electrode, the Ni-doped material achieved 13.3 F/g at 50 mA/g—66% higher than undoped samples. For Li-ion battery anodes, it reached a specific capacity of 410.5 mAh/g at 25 mA/g, outperforming undoped samples by 21.4%. Full article

(This article belongs to the Special Issue Metal Organic Framework (MOF)-Based Micro/Nanoscale Materials)

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SEM images of ZIF-L coating on carbon fiber fabric at (a) lower magnification and (b) higher magnification, (c) undoped TMO sample, (d) Zn-doped TMO sample, (e) Mn-doped TMO sample, and (f) Ni-doped TMO sample. Full article ">Figure 2
(a) XPS surveys. (b) XPS Co 2p core level of the undoped sample. (c) XPS Zn 2p core level of Zn-doped sample. (d) XPS Mn 2p core level of Mn-doped sample. (e) XPS Ni 2p core level of Ni-doped sample. (f) The atomic percentage of each cation in each sample. (g) XRD spectra of TMO powder samples. Full article ">Figure 3
TEM images of undoped TMO samples at (a) lower and (b) higher magnification. Full article ">Figure 4
(a) CV curves at a scan rate of 20 mV/s. (b) Specific capacitance values are calculated from CV at 20 mV/s. (c) GCD test discharges at 50 mA/g. (d) Specific capacitance calculated from GCD tests at different current densities. Full article ">Figure 5
(a) CV curve of Ni-doped sample at different scan rates and (b) calculated b value in the inset. (c) Diffusion and capacitive-controlled processes contribute to different scan rates for Ni-doped samples. (d) Specific capacitance and coulombic efficiency of Ni-doped sample after 5000 GCD cycles at 150 mA/g. Full article ">Figure 6
(a) Normalized third-cycle CV of the samples. (b) GCD curves at 25 mA/g of the samples. (c) GCD calculated capacities at different current densities. (d) Nyquist plots of the samples. Full article ">Figure 7
(a) Ni-doped sample CV at different scan rates and calculated b value in the inset. (b) Percentage of each contribution at different scan rates in the Ni-doped sample. (c) Specific capacity of Ni-doped sample after 100 GCD cycles at 100 mA/g. (d) Nyquist plot of Ni-doped sample after several number of cycles. Full article ">

5 pages, 198 KiB

Open AccessEditorial

Micro- and Nanostructured Biomaterials for Biomedical Applications and Regenerative Medicine

by Michele Bianchi and Gianluca Carnevale

Nanomaterials 2024, 14(22), 1845; https://doi.org/10.3390/nano14221845 - 18 Nov 2024

Viewed by 1068

Abstract

Over the past two decades, research on innovative micro- and nano-biomaterials has seen a significant surge in the bioengineering, biomedicine, and regenerative medicine fields [...] Full article

(This article belongs to the Special Issue Micro- and Nanostructured Biomaterials for Biomedical Applications and Regenerative Medicine)

13 pages, 3286 KiB

Open AccessArticle

Improving the NO₂ Gas Sensing Performances at Room Temperature Based on TiO₂ NTs/rGO Heterojunction Nanocomposites

by Yan Ling, Yunjiang Yu, Canxin Tian and Changwei Zou

Nanomaterials 2024, 14(22), 1844; https://doi.org/10.3390/nano14221844 - 18 Nov 2024

Cited by 1 | Viewed by 887

Abstract

The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO₂ concentrations has garnered considerable attention in recent years. In this manuscript, TiO₂ nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO₂ NTs/rGO) were synthesized via a two-step [...] Read more.

The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO₂ concentrations has garnered considerable attention in recent years. In this manuscript, TiO₂ nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO₂ NTs/rGO) were synthesized via a two-step method for room temperature NO₂ gas detection. From SEM and TEM images, it is evident that the rGO sheets not only partially surround the TiO₂ nanotubes but also establish interconnection bridges between adjacent nanotubes, which is anticipated to enhance electron–hole separation by facilitating electron transfer. The optimized TiO₂ NTs/rGO sensor demonstrated a sensitive response of 19.1 to 1 ppm of NO₂, a 5.26-fold improvement over the undoped TiO₂ sensor. Additionally, rGO doping significantly enhanced the sensor’s response/recovery times, reducing them from 24 s/42 s to 18 s/33 s with just 1 wt.% rGO. These enhancements are attributed to the increased specific surface area, higher concentration of chemisorbed oxygen species, and the formation of p-n heterojunctions between TiO₂ and rGO within the nanocomposites. This study provides valuable insights for the development of TiO₂/graphene-based gas sensors for detecting oxidizing gases at room temperature. Full article

(This article belongs to the Special Issue Design and Applications of Heterogeneous Nanostructured Materials)

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12 pages, 5364 KiB

Open AccessArticle

Controlled Formation of Silicon-Vacancy Centers in High-Pressure Nanodiamonds Produced from an “Adamantane + Detonation Nanodiamond” Mixture

by Dmitrii G. Pasternak, Rustem H. Bagramov, Alexey M. Romshin, Igor P. Zibrov, Vladimir P. Filonenko and Igor I. Vlasov

Nanomaterials 2024, 14(22), 1843; https://doi.org/10.3390/nano14221843 - 18 Nov 2024

Viewed by 916

Abstract

Despite progress in the high-pressure synthesis of nanodiamonds from hydrocarbons, the problem of controlled formation of fluorescent impurity centers in them still remains unresolved. In our work, we explore the potential of a new precursor composition, a mixture of adamantane with detonation nanodiamond, [...] Read more.

Despite progress in the high-pressure synthesis of nanodiamonds from hydrocarbons, the problem of controlled formation of fluorescent impurity centers in them still remains unresolved. In our work, we explore the potential of a new precursor composition, a mixture of adamantane with detonation nanodiamond, both in the synthesis of nanodiamonds and in the controlled formation of negatively charged silicon-vacancy centers in such nanodiamonds. Using different adamantane/detonation nanodiamond weight ratios, a series of samples was synthesized at a pressure of 7.5 GPa in the temperature range of 1200–1500 °C. It was found that temperature around 1350 °C, is optimal for the high-yield synthesis of nanodiamonds <50 nm in size. For the first time, controlled formation of negatively charged silicon-vacancy centers in such small nanodiamonds was demonstrated by varying the atomic ratios of silicon/carbon in the precursor in the range of 0.01–1%. Full article

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13 pages, 2793 KiB

Open AccessArticle

Nature of the Pits on the Lattice-Matched InAlAs Layer Surface Grown on the (001) InP Substrate

by Dmitrii V. Gulyaev, Demid S. Abramkin, Dmitriy V. Dmitriev, Alexander I. Toropov, Eugeniy A. Kolosovsky, Sergey A. Ponomarev, Nina N. Kurus, Ilya A. Milekhin and Konstantin S. Zhuravlev

Nanomaterials 2024, 14(22), 1842; https://doi.org/10.3390/nano14221842 - 18 Nov 2024

Viewed by 772

Abstract

The structural properties of lattice-matched InAlAs/InP layers grown by molecular beam epitaxy have been studied using atomic force microscopy, scanning electron microscopy and micro-photoluminescence spectroscopy. The formation of the surface pits with lateral sizes in the micron range and a depth of about [...] Read more.

The structural properties of lattice-matched InAlAs/InP layers grown by molecular beam epitaxy have been studied using atomic force microscopy, scanning electron microscopy and micro-photoluminescence spectroscopy. The formation of the surface pits with lateral sizes in the micron range and a depth of about 2 ÷ 10 nm has been detected. The InP substrate annealing temperature and value of InAlAs alloy composition deviation from the lattice-matched In_xAl_1−xAs/InP case (x = 0.52) control the density of pits ranging from 5 × 10⁵ cm⁻² ÷ 10⁸ cm⁻². The pit sizes are controlled by the InAlAs layer thickness and growth temperature. The correlation between the surface pits and threading dislocations has been detected. Moreover, the InAlAs surface is characterized by composition inhomogeneity with a magnitude of 0.7% with the cluster lateral sizes and density close to these parameters for surface pits. The experimental data allow us to suggest a model where the formation of surface pits and composition clusters is caused by the influence of a local strain field in the threading dislocation core vicinity on In adatoms incorporating kinetic. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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Scheme of structures with InxAl1−xAs layer with thickness D grown at TS. The preparation of the InP substrate was performed at TA. The InAsP layer, formed during the substrate preparation, is marked as «InAsP». Full article ">Figure 2
AFM images of 1 μm thick InAlAs layers lattice-matched with the substrate. TA = 485 °C and TS = 485 °C for (A) and TA = 535 °C, TS = 525 °C for (B). Total layer thickness is 1000 nm for both structures. Relief profiles are presented in the insets. Full article ">Figure 3
(a) The dependence of the pit density on the substrate annealing temperature for the lattice-matched layer (x = 0.52, black dots) and on the layer composition deviation from the lattice-matched value (red dots). (b) The dependence of the lateral size of the pits on the InAlAs layer thickness for x = 0.52 (black dots) and x = 0.51 (red dots). (c) The dependence of the depth of the pits on the thickness of the InAlAs layer with x = 0.52 grown at the temperature of 505 °C. (d) The dependence of the depth of the pits on the growth temperature for the InAlAs layer with x = 0.52 grown at the total layer thickness of 1 μm. Full article ">Figure 4
The SEM cross-sectional image of the heterostructure grown at TA = 535 °C, TS = 525 °C and D = 1000 nm, with the alloy composition deviation of 0.5%. The vertical arrows at the top panel point to the surface pits. The bottom panel shows the same area of the SEM image but with the dislocations indicated by thin white lines for better clarity. Full article ">Figure 5
(A) A typical map of the position of the PL peak of the InAlAs layer with pits. (B) Micro-PL spectra from the InAlAs layer measured (1) inside and (outside) the cluster. The annealing temperature of the substrate/growth is 535/505 °C. Full article ">Figure 6
Experimental and calculated temperature dependencies of the pit depth (black square) and In depletion (red circle) for lattice-matched 1 μm thick InAlAs layers. Full article ">

11 pages, 2655 KiB

Open AccessArticle

Enhanced Optical and Electrical Properties of IGZO/Ag/IGZO for Solar Cell Application via Post-Rapid Thermal Annealing

by Chanmin Hwang, Taegi Kim, Yuseong Jang, Doowon Lee and Hee-Dong Kim

Nanomaterials 2024, 14(22), 1841; https://doi.org/10.3390/nano14221841 - 18 Nov 2024

Viewed by 2090

Abstract

In this paper, we optimized IGZO/Ag/IGZO (IAI) multilayer films by post-rapid thermal annealing (RTA) to enhance the electrical conductivity and optical transmittance in visible wavelengths for solar cell applications. Our optimized device showed an average transmittance of 85% in the visible range, with [...] Read more.

In this paper, we optimized IGZO/Ag/IGZO (IAI) multilayer films by post-rapid thermal annealing (RTA) to enhance the electrical conductivity and optical transmittance in visible wavelengths for solar cell applications. Our optimized device showed an average transmittance of 85% in the visible range, with a lowest sheet resistance of 6.03 Ω/□ when annealed at 500 °C for 60 s. Based on these results, we assessed our device with photo-generated short circuit current density (J_SC) using a solar cell simulator to confirm its applicability in the solar cell. IAI multilayer RTA at 500 °C for 60 s showed a highest J_SC of 40.73 mA/cm². These results show that our proposed IAI multilayer film, which showed a high optical transparency and electrical conductivity optimized with post RTA, seems to be excellent transparent electrode for solar cell applications. Full article

(This article belongs to the Special Issue Nanostructured Materials for Electric Applications)

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The RTA process for the IGZO/Ag/IGZO multilayer, and the right diagram describes the generated oxygen vacancies from the IGZO inside by RTA. Full article ">Figure 2
AFM topology images of IGZO/Ag/IGZO after RTA, (a) RT, (b) 300, (c) 400, and (d) 500 °C for 60 s. Full article ">Figure 3
The sheet resistance of (a) IGZO and (b) IGZO/Ag/IGZO multilayers after varying temperature conditions. Full article ">Figure 4
(a) Impedance of IGZO/Ag/IGZO after RTA RT to 500 °C for 60 s and (b) equivalent circuit of IGZO/Ag/IGZO. Full article ">Figure 5
(a) Transmittance, (b) reflectivity, and (c) absorption coefficient of IGZO/Ag/IGZO after RTA RT to 500 °C for 60 s, and each inset depicts the transmittance and reflectivity at 500 nm wavelength with varying annealing temperature. Full article ">Figure 6
(a) Schematic structure of IGZO/Ag/IGZO-based solar cell and (b) the photo-generated short circuit current of IGZO/Ag/IGZO-based solar cell as a function of annealing temperature. Full article ">

18 pages, 2873 KiB

Open AccessArticle

Improving Resistive Heating, Electrical and Thermal Properties of Graphene-Based Poly(Vinylidene Fluoride) Nanocomposites by Controlled 3D Printing

by Rumiana Kotsilkova, Vladimir Georgiev, Mariya Aleksandrova, Todor Batakliev, Evgeni Ivanov, Giovanni Spinelli, Rade Tomov and Tsvetozar Tsanev

Nanomaterials 2024, 14(22), 1840; https://doi.org/10.3390/nano14221840 - 17 Nov 2024

Viewed by 1400

Abstract

This study developed a novel 3D-printable poly(vinylidene fluoride) (PVDF)-based nanocomposite incorporating 6 wt% graphene nanoplatelets (GNPs) with programmable characteristics for resistive heating applications. The results highlighted the significant effect of a controlled printing direction (longitudinal, diagonal, and transverse) on the electrical, thermal, Joule [...] Read more.

This study developed a novel 3D-printable poly(vinylidene fluoride) (PVDF)-based nanocomposite incorporating 6 wt% graphene nanoplatelets (GNPs) with programmable characteristics for resistive heating applications. The results highlighted the significant effect of a controlled printing direction (longitudinal, diagonal, and transverse) on the electrical, thermal, Joule heating, and thermo-resistive properties of the printed structures. The 6 wt% GNP/PVDF nanocomposite exhibited a high electrical conductivity of 112 S·m⁻¹ when printed in a longitudinal direction, which decreased significantly in other directions. The Joule heating tests confirmed the material’s efficiency in resistive heating, with the maximum temperature reaching up to 65 °C under an applied low voltage of 2 V at a raster angle of printing of 0°, while the heating T_max decreased stepwise with 10 °C at the 45° and the 90° printing directions. The repeatability of the Joule heating performance was verified through multiple heating and cooling cycles, demonstrating consistent maximum temperatures across several tests. The effect of sample thickness, controlled by the number of printed layers, was investigated, and the results underscore the advantages of programmable 3D printing orientation in thin layers for enhanced thermal stability, tailored electrical conductivity, and efficient Joule heating capabilities of 6 wt% GNP/PVDF composites, positioning them as promising candidates for next-generation 3D-printed electronic devices and self-heating applications. Full article

(This article belongs to the Special Issue Hybrid Nano Polymer Composites (2nd Edition))

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45 pages, 11195 KiB

Open AccessReview

Exploring Plasmonic Standalone Surface-Enhanced Raman Scattering Nanoprobes for Multifaceted Applications in Biomedical, Food, and Environmental Fields

by Valentina Rojas Martínez, Eunseo Lee and Jeong-Wook Oh

Nanomaterials 2024, 14(22), 1839; https://doi.org/10.3390/nano14221839 - 17 Nov 2024

Cited by 1 | Viewed by 1721

Abstract

Surface-enhanced Raman scattering (SERS) is an innovative spectroscopic technique that amplifies the Raman signals of molecules adsorbed on rough metal surfaces, making it pivotal for single-molecule detection in complex biological and environmental matrices. This review aims to elucidate the design strategies and recent [...] Read more.

Surface-enhanced Raman scattering (SERS) is an innovative spectroscopic technique that amplifies the Raman signals of molecules adsorbed on rough metal surfaces, making it pivotal for single-molecule detection in complex biological and environmental matrices. This review aims to elucidate the design strategies and recent advancements in the application of standalone SERS nanoprobes, with a special focus on quantifiable SERS tags. We conducted a comprehensive analysis of the recent literature, focusing on the development of SERS nanoprobes that employ novel nanostructuring techniques to enhance signal reliability and quantification. Standalone SERS nanoprobes exhibit significant enhancements in sensitivity and specificity due to optimized hot spot generation and improved reporter molecule interactions. Recent innovations include the development of nanogap and core–satellite structures that enhance electromagnetic fields, which are crucial for SERS applications. Standalone SERS nanoprobes, particularly those utilizing indirect detection mechanisms, represent a significant advancement in the field. They hold potential for wide-ranging applications, from disease diagnostics to environmental monitoring, owing to their enhanced sensitivity and ability to operate under complex sample conditions. Full article

(This article belongs to the Special Issue Versatile Plasmonic Nanostructures for Biomedical Applications)

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12 pages, 5559 KiB

Open AccessArticle

Potassium-Based Solid Sorbents for CO₂ Adsorption: Key Role of Interconnected Pores

by Yuan Zhao, Jiangbo Huo, Xuefei Wang and Shunwei Ma

Nanomaterials 2024, 14(22), 1838; https://doi.org/10.3390/nano14221838 - 17 Nov 2024

Viewed by 885

Abstract

Industrial CO₂ emissions contribute to pollution and greenhouse effects, highlighting the importance of carbon capture. Potassium carbonate (K₂CO₃) is an effective CO₂ absorbent, yet its liquid-phase absorption faces issues like diffusion resistance and corrosion risks. In this [...] Read more.

Industrial CO₂ emissions contribute to pollution and greenhouse effects, highlighting the importance of carbon capture. Potassium carbonate (K₂CO₃) is an effective CO₂ absorbent, yet its liquid-phase absorption faces issues like diffusion resistance and corrosion risks. In this work, the solid adsorbents were developed with K₂CO₃ immobilized on the selected porous supports. Al₂O₃ had an optimum CO₂ adsorption capacity of 0.82 mmol g⁻¹. After further optimization of its pore structure, the self-prepared support Al₂O₃-2, which has an average pore diameter of 11.89 nm and a pore volume of 0.59 cm³ g⁻¹, achieved a maximum CO₂ adsorption capacity of 1.12 mmol g⁻¹ following K₂CO₃ impregnation. Additionally, the relationship between support structure and CO₂ adsorption efficiency was also analyzed. The connectivity of the pores and the large pore diameter of the support may play a key role in enhancing CO₂ adsorption performance. During 10 cycles of testing, the K₂CO₃-based adsorbents demonstrated consistent high CO₂ adsorption capacity with negligible degradation. Full article

(This article belongs to the Topic Removing Challenging Pollutants from Wastewater: Effective Approaches)

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19 pages, 6771 KiB

Open AccessArticle

Enhancement of the Physical and Mechanical Properties of Cellulose Nanofibril-Reinforced Lignocellulosic Foams for Packaging and Building Applications

by Mara Paulette Alonso, Rakibul Hossain, Maryam El Hajam and Mehdi Tajvidi

Nanomaterials 2024, 14(22), 1837; https://doi.org/10.3390/nano14221837 - 17 Nov 2024

Viewed by 1498

Abstract

Biobased foams have the potential to serve as eco-friendly alternatives to petroleum-based foams, provided they achieve comparable thermomechanical and physical properties. We propose a facile approach to fabricate eco-friendly cellulose nanofibril (CNF)-reinforced thermomechanical pulp (TMP) fiber-based foams via an oven-drying process with thermal [...] Read more.

Biobased foams have the potential to serve as eco-friendly alternatives to petroleum-based foams, provided they achieve comparable thermomechanical and physical properties. We propose a facile approach to fabricate eco-friendly cellulose nanofibril (CNF)-reinforced thermomechanical pulp (TMP) fiber-based foams via an oven-drying process with thermal conductivity as low as 0.036 W/(m·K) at a 34.4 kg/m³ density. Acrodur^®, iron chloride (FeCl₃), and cationic polyacrylamide (CPAM) were used to improve the foam properties. Acrodur^® did not have any significant effect on the foamability and density of the foams. Mechanical, thermal, cushioning, and water absorption properties of the foams were dependent on the density and interactions of the additives with the fibers. Due to their high density, foams with CPAM and FeCl₃ at a 1% additive dosage had significantly higher compressive properties at the expense of slightly higher thermal conductivity. There was slight increase in compressive properties with the addition of Acrodur^®. All additives improved the water stability of the foams, rendering them stable even after 24 h of water absorption. Full article

(This article belongs to the Special Issue Advanced Porous Nanomaterials: Synthesis, Properties, and Application (Second Edition))

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15 pages, 3359 KiB

Open AccessArticle

Improvement in Curcumin’s Stability and Release by Formulation in Flexible Nano-Liposomes

by Hua-Wei Chen, Su-Der Chen, Hung-Ta Wu, Chun-Hung Cheng, Chyow-San Chiou and Wei-Ting Chen

Nanomaterials 2024, 14(22), 1836; https://doi.org/10.3390/nano14221836 - 17 Nov 2024

Cited by 2 | Viewed by 1153

Abstract

Curcumin is utilized extensively as Chinese medicine in Asia due to its antioxidant, antimicrobial, and inflammatory activities. However, its use has the challenges of low oral bioavailability and high heat sensitivity. The aim of this research was to produce flexible nano-liposomes containing curcumin [...] Read more.

Curcumin is utilized extensively as Chinese medicine in Asia due to its antioxidant, antimicrobial, and inflammatory activities. However, its use has the challenges of low oral bioavailability and high heat sensitivity. The aim of this research was to produce flexible nano-liposomes containing curcumin using an innovative approach of ethanol injection and Tween 80 to enhance the stability and preservation of curcumin. The mean particle size, encapsulation efficiency, thermal degradation, storage stability, and curcumin release in flexible nano-liposomes were also investigated. We found that the mean particle size of curcumin-loaded flexible nano-liposome decreased from 278 nm to 27.6 nm. At the same time, the Tween 80 concentration increased from 0 to 0.15 wt%, which corresponded with the results of transmission electron microscopy (TEM) morphology analyses, and particle size decreased with an enhancement in Tween 80 concentration. Further, pure curcumin was quickly released within one hour at 37 °C, and first-order kinetics matched with its release curve. However, curcumin encapsulated in flexible nano-liposomes showed a slow release of 71.24% within 12 h, and a slower release pattern matched with the Higuchi model over 24 h, ultimately reaching 84.63% release. Hence, flexible nano-liposomes of curcumin made by a combination of ethanol injection and Tween 80 addition prevented the thermal degradation of curcumin, and enhanced its storage stability and preservation for future drug delivery applications. Full article

(This article belongs to the Special Issue Green Nanoparticles for Topical Administration of Drugs)

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17 pages, 3778 KiB

Open AccessArticle

High-Performance Ammonia QCM Sensor Based on SnO₂ Quantum Dots/Ti₃C₂T_x MXene Composites at Room Temperature

by Chong Li, Ran Tao, Jinqiao Hou, Huanming Wang, Chen Fu and Jingting Luo

Nanomaterials 2024, 14(22), 1835; https://doi.org/10.3390/nano14221835 - 16 Nov 2024

Viewed by 1124

Abstract

Ammonia (NH₃) gas is prevalent in industrial production as a health hazardous gas. Consequently, it is essential to develop a straightforward, reliable, and stable NH₃ sensor capable of operating at room temperature. This paper presents an innovative approach to modifying [...] Read more.

Ammonia (NH₃) gas is prevalent in industrial production as a health hazardous gas. Consequently, it is essential to develop a straightforward, reliable, and stable NH₃ sensor capable of operating at room temperature. This paper presents an innovative approach to modifying SnO₂ colloidal quantum dots (CQDs) on the surface of Ti₃C₂T_x MXene to form a heterojunction, which introduces a significant number of adsorption sites and enhances the response of the sensor. Zero-dimensional (0D) SnO₂ quantum dots and two-dimensional (2D) Ti₃C₂T_x MXene were prepared by solvothermal and in situ etching methods, respectively. The impact of the mass ratio between two materials on the performance was assessed. The sensor based on 12 wt% Ti₃C₂T_x MXene/SnO₂ composites demonstrates excellent performance in terms of sensitivity and response/recovery speed. Upon exposure to 50 ppm NH₃, the frequency shift in the sensor is −1140 Hz, which is 5.6 times larger than that of pure Ti₃C₂T_x MXene and 2.8 times higher than that of SnO₂ CQDs. The response/recovery time of the sensor for 10 ppm NH₃ was 36/54 s, respectively. The sensor exhibited a theoretical detection limit of 73 ppb and good repeatability. Furthermore, a stable sensing performance can be maintained after 30 days. The enhanced sensor performance can be attributed to the abundant active sites provided by the accumulation/depletion layer in the Ti₃C₂T_x/SnO₂ heterojunction, which facilitates the adsorption of oxygen molecules. This work promotes the gas sensing application of MXenes and provides a way to improve gas sensing performance. Full article

(This article belongs to the Special Issue Synthesis, Chemical-Physical Properties and Applications of Quantum Dots Nanocrystals)

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15 pages, 5249 KiB

Open AccessEditor’s ChoiceArticle

A Comprehensive Microstructure-Aware Electromigration Modeling Framework; Investigation of the Impact of Trench Dimensions in Damascene Copper Interconnects

by Ahmed Sobhi Saleh, Kristof Croes, Hajdin Ceric, Ingrid De Wolf and Houman Zahedmanesh

Nanomaterials 2024, 14(22), 1834; https://doi.org/10.3390/nano14221834 - 16 Nov 2024

Cited by 2 | Viewed by 769

Abstract

As electronic devices continue to shrink in size and increase in complexity, the current densities in interconnects drastically increase, intensifying the effects of electromigration (EM). This renders the understanding of EM crucial, due to its significant implications for device reliability and longevity. This [...] Read more.

As electronic devices continue to shrink in size and increase in complexity, the current densities in interconnects drastically increase, intensifying the effects of electromigration (EM). This renders the understanding of EM crucial, due to its significant implications for device reliability and longevity. This paper presents a comprehensive simulation framework for the investigation of EM in nano-interconnects, with a primary focus on unravelling the influential role of microstructure, by considering the impact of diffusion heterogeneity through the metal texture and interfaces. As such, the resulting atomic flux and stress distribution within nano-interconnects could be investigated. To this end, a novel approach to generate microstructures of the conductor metal is presented, whereby a predefined statistical distribution of grain sizes obtained from experimental texture analyses can be incorporated into the presented model, making the model predictive under various scales and working conditions with no need for continuous calibration. Additionally, the study advances beyond the state-of-the-art by comprehensively simulating all stages of electromigration including stress evolution, void nucleation, and void dynamics. The model was employed to study the impact of trench dimensions on the dual damascene copper texture and its impact on electromigration aging, where the model findings were corroborated by comparing them to the available experimental findings. A nearly linear increase in normalized time to nucleation was detected as the interconnect became wider with a fixed height for aspect ratios beyond 1. However, a saturation was detected with a further increase in width for lines of aspect ratios below 1, with no effective enhancement in time to nucleation. An aspect ratio of 1 seems to maximize the EM lifetime for a fixed cross-sectional area by fostering a bamboo-like structure, where about a 2-fold of increase was estimated when going from aspect ratio 2 to 1. Full article

(This article belongs to the Special Issue Mechanical and Thermal Properties of Nanomaterials)

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21 pages, 2882 KiB

Open AccessEditor’s ChoiceReview

Gold Nanoprobes for Robust Colorimetric Detection of Nucleic Acid Sequences Related to Disease Diagnostics

by Maria Enea, Andreia Leite, Ricardo Franco and Eulália Pereira

Nanomaterials 2024, 14(22), 1833; https://doi.org/10.3390/nano14221833 - 16 Nov 2024

Viewed by 1489

Abstract

Gold nanoparticles (AuNPs) are highly attractive for applications in the field of biosensing, particularly for colorimetric nucleic acid detection. Their unique optical properties, which are highly sensitive to changes in their environment, make them ideal candidates for developing simple, rapid, and cost-effective assays. [...] Read more.

Gold nanoparticles (AuNPs) are highly attractive for applications in the field of biosensing, particularly for colorimetric nucleic acid detection. Their unique optical properties, which are highly sensitive to changes in their environment, make them ideal candidates for developing simple, rapid, and cost-effective assays. When functionalized with oligonucleotides (Au-nanoprobes), they can undergo aggregation or dispersion in the presence of complementary sequences, leading to distinct color changes that serve as a visual signal for detection. Aggregation-based assays offer significant advantages over other homogeneous assays, such as fluorescence-based methods, namely, label-free protocols, rapid interactions in homogeneous solutions, and detection by the naked eye or using low-cost instruments. Despite promising results, the application of Au-nanoprobe-based colorimetric assays in complex biological matrices faces several challenges. The most significant are related to the colloidal stability and oligonucleotide functionalization of the Au-nanoprobes but also to the mode of detection. The type of functionalization method, type of spacer, the oligo–AuNPs ratio, changes in pH, temperature, or ionic strength influence the Au-nanoprobe colloidal stability and thus the performance of the assay. This review elucidates characteristics of the Au-nanoprobes that are determined for colorimetric gold nanoparticles (AuNPs)-based nucleic acid detection, and how they influence the sensitivity and specificity of the colorimetric assay. These characteristics of the assay are fundamental to developing low-cost, robust biomedical sensors that perform effectively in biological fluids. Full article

(This article belongs to the Special Issue Noble Metal-Based Nanostructures: Optical Properties and Applications)

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Timeline of AuNPs use for nucleic acid detection. Full article ">Figure 2
Dependence of LSPR on spherical gold nanoparticles diameter and aggregation state. Full article ">Figure 3
Colorimetric detection methods using spherical AuNPs: (Top panel) Cross-linking assay—a color change occurs as nucleic acid sequence strands specifically hybridize with complementary sequences, reducing the distance between particles, and resulting in a blue solution (positive test). In the absence of complementary sequences, the solution stays red (negative test). (Middle panel) Non-cross-linking assay—an increase in ionic strength induces AuNP aggregation, resulting in a blue solution (negative test). When complementary targets are present, the solution stays red (positive test). (Bottom panel) Colorimetric assay using unmodified AuNPs: In the absence of complementary sequences, only single-stranded DNA (ssDNA) is present, stabilizing AuNPs against salt-induced aggregation, and the solution stays red (negative result). Conversely, when hybridization occurs in the presence of a complementary sequence, double-stranded DNA (dsDNA) forms, and aggregation occurs (blue solution is a positive result). UV/vis spectra and Nanoparticle Tracking analysis (NTA) profiles are shown with blue lines corresponding to aggregated AuNPs samples and red lines to non-aggregated ones. Also indicated are the positive (green check) and negative (red cross) results for each test. Full article ">Figure 4
Published successful functionalization methods of AuNPs with HS-oligos, resulting in Au-nanoprobes. Full article ">Figure 5
Examples of Au nanoparticle interaction with (i) ssDNA, (ii) PolyA-ssDNA and PolyT-ssDNA, (iii) PEG-ssDNA, and (iv) thiolated-(CH2)6-ssDNA. Full article ">

20 pages, 5333 KiB

Open AccessArticle

Green Synthesis of Fe₂O₃ Nanoparticles Using Eucalyptus globulus Leaf Extract on Pinus radiata Sawdust for Cationic Dye Adsorption

by Pablo Salgado, Eduardo Aedo and Gladys Vidal

Nanomaterials 2024, 14(22), 1832; https://doi.org/10.3390/nano14221832 - 16 Nov 2024

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Abstract

The present study reports the synthesis of Fe₂O₃ nanoparticles on Pinus radiata sawdust (Fe₂O₃@PS) using a Eucalyptus globulus leaf extract. The morphology and structure of Fe₂O₃@PS were characterized using scanning electron microscopy [...] Read more.

The present study reports the synthesis of Fe₂O₃ nanoparticles on Pinus radiata sawdust (Fe₂O₃@PS) using a Eucalyptus globulus leaf extract. The morphology and structure of Fe₂O₃@PS were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV–Vis diffuse reflectance. The adsorption capacity of the system was evaluated by testing its ability to remove the Rhodamine B (RhB) dye. The optimization of the system was carried out using the Plackett–Burman design (PBD) and the response surface methodology (steepest ascent and the Box–Behnken design), which provided information on the main parameters affecting the adsorption process. The PBD results showed that the most important parameters for the removal of RhB using Fe₂O₃@PS were the removal time, the RhB concentration, and the initial pH of the system. The reusability of Fe₂O₃@PS under optimal conditions was tested and it was found to maintain its efficiency after five cycles of use. The efficiency and rate of RhB removal observed at pH values near 7.0 were found to be predominantly influenced by electrostatic interactions. In contrast, the analyses conducted at pH values near 8.3 exhibited reduced influence from electrostatic attractions, with π–π interactions and hydrogen bonds emerging as dominant forces. At pH values exceeding 8.3, all potential interactions between RhB and Fe₂O₃@PS exhibited diminished strength. This research provides valuable information on the formation of eco-friendly nanoparticles immobilized on a forest residue such as sawdust, which can effectively remove organic pollutants like RhB. This contributes to the valorization of resources and the search for solutions to water pollution. Full article

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13 pages, 7273 KiB

Open AccessArticle

Catalytic Methane Decomposition on In Situ Reduced FeCo Alloy Catalysts Derived from Layered Double Hydroxides

by Dianfeng Cao, Yuwen Li, Chao Lv, Yongtao An, Jiangfeng Song, Mingcan Li and Xin Zhang

Nanomaterials 2024, 14(22), 1831; https://doi.org/10.3390/nano14221831 - 15 Nov 2024

Viewed by 701

Abstract

Catalytic methane decomposition (CMD) reaction is considered a promising process for converting greenhouse gas CH₄ into hydrogen and high-value-added carbon materials. In this work, a series of Al₂O₃-supported FeCo alloy catalysts were successfully prepared in the CMD process. [...] Read more.

Catalytic methane decomposition (CMD) reaction is considered a promising process for converting greenhouse gas CH₄ into hydrogen and high-value-added carbon materials. In this work, a series of Al₂O₃-supported FeCo alloy catalysts were successfully prepared in the CMD process. Compared to the pre-reduced catalysts, the in situ reduced FeCo alloy catalysts showed higher methane conversion rates, with the highest reaching 83% at 700 °C, due to the finer active nanoparticle size and greater exposure of active site. Furthermore, the time-on-stream tests demonstrated that the catalytic activity of in situ reduced FeCo alloy catalysts could remain above 92.3% of the highest catalytic activity after 10 h. In addition, TEM analyses of the carbon products from the CMD in situ reduced catalysts revealed the production of carbon nanofibers and nanotubes several microns in length after the reaction. This indicates that the in situ reduced FeCo alloy catalysts more effectively promoted the growth of carbon nanofibers. These results could provide a viable strategy for future methane decomposition development aimed at producing hydrogen and high-value carbon. Full article

(This article belongs to the Special Issue Nanomaterials for Sustainable Green Energy)

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(a) XRD patterns of FeCoAl-LDH-x and (b) XRD patterns of FeCo/Al2O3-x. Full article ">Figure 2
TEM images of (a–c) FeCoAl-LDH-x (x = 1–3). (d–f) TEM images of FeCo/Al2O3-x (x = 1–3). (g–i) Statistical distribution graphs of the particle size of FeCo/Al2O3-x (x = 1–3). Full article ">Figure 3
(a) TG analysis of the FeCoAl-LDH-x, (b) the differential curves of TG about FeCoAl-LDH-x, (c) TG analysis of the FeCo/Al2O3-x, and (d) the differential curves of TG about FeCo/Al2O3-x. Full article ">Figure 4
The relationship between methane conversion and temperature in the TPSR test at 5 °C/min to 800 °C for (a) FeCoAl-LDH-x and (b) FeCo/Al2O3-x, and the relationship between methane conversion and temperature in the TOS test at 5 °C/min to 700 °C for insulation of (c) FeCoAl-LDH-x and (d) FeCo/Al2O3-x. Full article ">Figure 5
XRD patterns of methane decomposition reaction products catalyzed by (a) FeCoAl-LDH-x and (b) FeCo/Al2O3-x. Full article ">Figure 6
TEM images of carbon products created by (a,b) FeCoAl-LDH-1, (c,d) FeCoAl-LDH-2, (e,f) and FeCoAl-LDH-3. Full article ">Figure 7
TEM images of TG products created by (a) FeCo/Al2O3-1, (b) FeCo/Al2O3-2, and (c) FeCo/Al2O3-3. Full article ">Figure 8
Raman spectra of (a) spent FeCoAl-LDHs-x (x = 1–3) and (b) FeCo/Al2O3-x (x = 1–3) catalysts after TG. Full article ">

14 pages, 7597 KiB

Open AccessArticle

Magnetic Field/Ultrasound-Responsive Fe₃O₄ Microbubbles for Targeted Mechanical/Catalytic Removal of Bacterial Biofilms

by Liang Lu, Yuan Liu, Xiaolong Chen, Fengjiao Xu, Qi Zhang, Zhaowei Yin and Lihui Yuwen

Nanomaterials 2024, 14(22), 1830; https://doi.org/10.3390/nano14221830 - 15 Nov 2024

Cited by 1 | Viewed by 975

Abstract

Conventional antibiotics are limited by drug resistance, poor penetration, and inadequate targeting in the treatment of bacterial biofilm-associated infections. Microbubble-based ultrasound (US)-responsive drug delivery systems can disrupt biofilm structures and enhance antibiotic penetration through cavitation effects. However, currently developed US-responsive microbubbles still depend [...] Read more.

Conventional antibiotics are limited by drug resistance, poor penetration, and inadequate targeting in the treatment of bacterial biofilm-associated infections. Microbubble-based ultrasound (US)-responsive drug delivery systems can disrupt biofilm structures and enhance antibiotic penetration through cavitation effects. However, currently developed US-responsive microbubbles still depend on antibiotics and lack targeting capability. In this work, magnetic field/ultrasound (MF/US)-responsive Fe₃O₄ microbubbles (FMB) were constructed based on Fe₃O₄ nanoparticles (NPs) with superparamagnetic and peroxidase-like catalytic properties. In vitro experiments demonstrated that FMB can be targeted to methicillin-resistant Staphylococcus aureus (MRSA) biofilms by the direction of MF. Upon US irradiation, FMB collapse due to inertial cavitation and generate mechanical forces to disrupt the structure of MRSA biofilms and releases Fe₃O₄ NPs, which catalyze the generation of reactive oxygen species (ROS) from H₂O₂ in the biofilm microenvironment and kill the bacteria within the biofilm. In a mouse biofilm infection model, FMB efficiently destroyed MRSA biofilms grown in subcutaneous catheters with the MF and US. Magnetic-targeted mechanical/catalytic therapy based on FMB provides a promising strategy for effectively combating bacterial biofilm infection. Full article

(This article belongs to the Special Issue Stimuli-Responsive Nanomaterials for Imaging and Therapy)

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